Soldering

Soldering Tools

General


Historically soldering tips were copper, placed in braziers. One tip was used; when the heat had transferred from the tip to the solder (and depleted the heat reserve) it was placed back in the brazier of charcoal and the next tip was used.

Much later gas irons were in common use. These used a gas jet to heat the soldering bolt/tip. They are very fast, but require significant amounts of experience to properly regulate the temperature.

Currently, electric soldering irons are used; they consist of coil or ceramic heating elements, which retain heat differently, and warm up the mass differently, internal or external rheostats, and different power ratings - which change how long a bead can be run.

Soldering Irons

The iron used to solder must be of a high enough wattage to readily melt the solder and be able to reheat fast enough to maintain the necessary melting temperature. The tip can't be so small it can't maintain the heat nor so big it covers more area than wanted.

For example a 75 or 80 watt iron is sufficient to begin soldering with, but it will continue to get hotter, as it has no temperature control. An iron of this type should be used with a rheostat in order to prevent overheating while it is idling. You should be aware that even with a rheostat, it will eventually reach its maximum temperature, so cannot be left on for long. Also leaving an iron idling will contribute to the rapid deterioration of the tip.

Most temperature controlled irons seem to be produced in 100 watts or more. These internally temperature controlled irons maintain a constant temperature. These are normally supplied with a 700F° bit (number 7) and are sufficient to melt the solder without long recovery times. You can obtain bits of different temperature ratings, commonly 800F° and 600F°. You can also use several sizes of tips for different detail of work.

For soldering leaded panels a 100w iron with a 10 mm temperature controlled tip that maintains a constant 370°C (700° F) is suitable.

For copper foil a higher temperature controlled tip is used. This normally runs at 425°C (800°F). Sometimes a tip of 6 mm is used where more delicate beads are being run, but be aware that the tip will cool off much more quickly than 10 mm tips.

If a lot of soldering is required that has sustained heat requirements, you might consider a 200W iron. These can deliver heat more quickly and evenly than those with lesser wattage.

People often want to have variable temperatures for decorative soldering.

It is recommended to use a rheostat in circumstances where the soldering iron does not have an internal temperature control.

Action of a Rheostat

A rheostat is NOT a temperature controller.

A rheostat actually reduces the power supplied to the iron, thereby making it take longer to heat or re-heat after a period of soldering. With or without a rheostat, if an iron is left idle, it will eventually reach its maximum temperature. This is usually too hot for soldering lead, but OK for joining other metals. With a rheostat, if an iron is left idle with the rheostat set to (say) '6', it will still reach its maximum temperature but very much slower than the one without a rheostat.

Action of a Temperature Controlled Iron


Temperature controlled soldering irons attempt to maintain a set temperature. This is controlled by the combination of the microchip in the iron and the tip. So to adjust your temperatures all you need is a few different tips. For example, a number 7 tip lets your iron heat to 700F degrees. For decorative soldering your need tips of lower temperatures, usually a number 6 or 600F degree is enough of a reduction for most decorative stuff. A number 8 tip (800F) will let you work more quickly.

Differences in Soldering Speed


Using an iron without a rheostat, provided you work relatively quickly, you will probably be able to solder all the joints in a small or medium panel without stopping to let the iron 'catch up'. In this case the temperature is controlled by the heating power of the iron balanced by the cooling effect of making the soldered joints.

Using an iron with a rheostat, you will need to slow down a little if you are to do that same panel without stopping to let the iron re-heat. In this case the temperature of the iron is controlled by the (reduced) heating power of the iron balanced by the same cooling effect of making the soldered joints.

This difference is caused by the fact that a temperature-controlled iron, if it is left idle, it will quickly reach its maximum operating temperature - just as quickly as an uncontrolled iron of the same power. When you start soldering, the cooling effect will trigger the temperature controller to provide full power until the operating temperature is reached again.

Advantages of a Temperature Controlled Iron

You can buy an iron (not temperature controlled) and a rheostat but buying tips for the temperature controlled iron is cheaper. The big advantage of the temperature-controlled iron is that you know it will never get too hot for the work you are doing, and that it truly provides that 100 watts (or whatever) power to keep it hot even when you are soldering at top speed.

Soldering Bit Composition

Most bits are made of copper, which is suitable because of its excellent thermal conductivity and high heat content per volume. Some bits are plain copper, while others incorporate various additives or have a protective plating applied.

One of the most common problems associated with plain copper bits, is that tin-lead alloys (more specifically the tin in the alloy) will attack the copper, dissolving it away. This makes it necessary to continually file the bits to maintain the required shape, giving these bits a shortened working life. Another concern is the amount of impurity that is imparted to the solder joint when using bare copper bits.

Adding tellurium to the copper improves both wear and oxidation resistance, but does not protect the tip from rapid deterioration. It has been determined that both iron and nickel, despite their low conductivity, are wet-able, offer a high level of resistance to erosion and their heat per volume is close to that of copper.

Because of these facts it is possible to maintain good conductivity, while increasing the erosion resistance by plating copper bits with either nickel or iron. These plated bits are generally referred to as nickel-clad, or iron-clad and make up a large majority of the bits in use for modern soldering applications.

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Soldering Bits

Type

The bit type is determined by the soldering iron it is used on. There are screw type bits (bits that screw onto, or into the solder iron element), slip on bits that slip over the element and plug type bits that slide inside of the element. There are even bits that are a permanent part of a replaceable element/bit assembly. Regardless of the type of bits required it is always important to have them fully seated to the element and periodically cleaned, in order to maintain proper heat transfer from the element into the bit.

Configuration


The bit configuration to use should be determined by the intended application requirements. Some of the basic bit configurations available include ballpoint, conical, diamond (pyramid), chisel, and spade. You will find that there are usually a variety of styles, or modifications available, within each of these basic configuration families, to accommodate specific application requirements. Although less efficient, a more narrow configuration is sometimes required to obtain accessibility, or to achieve the desired results.

Size


The bit size to use (regarding the working portion) should also be determined by the intended application requirements. The bit body, or shank must be matched to the iron it will be used with (always select a bit that was designed, or approved for the soldering iron you intend to use on the application being considered). As with bit configuration though, there are usually a variety of modified working diameters available within each family of standard bit sizes that are available. These modified bits are generally referred to as turned down bits, because the working area of the bit has been turned down to a smaller diameter than the body, or shank diameter. Turned down bits are not as efficient, but are sometimes required to solder in otherwise inaccessible areas.

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Choosing the Soldering Bit

An important consideration, when choosing the most appropriate bit, is that thick, short bits will store more heat and deliver it more efficiently than long, narrow ones. This makes the standard chisel configuration the usual bit of choice. The chisel shaped bit is often used for joining flat seems together. The working edge of the chisel bit should be about the same width as (or slightly wider than) the seam that is being soldered.

Usually a solder connection is made in one to three seconds. If the connection takes longer than three seconds, you may need a larger bit, a higher wattage iron or a completely different type of soldering equipment altogether. It is a good idea to familiarize yourself with other soldering methods and equipment that are available in order to ensure that you are utilizing the best, safest, most efficient and economical means available to perform your soldering application.

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Soldering Bit Maintenance

If a bit has not been properly tinned, solder will not wet to it. Without solder on the bit heat transfer from the bit to the work surface may become extremely difficult and time consuming, or even impossible.

You must understand that proper wiping and continuous wetting is important and a lot easier than continually having to clean and re-tin the bit, especially at the risk of damage to the plated surface because of accidentally scratching, or over abrading it. [Many soldering stations come with a sponge which, when wet, is used to wipe the iron's tip clean. A small amount of fresh solder is usually then applied to the clean tip in a process called tinning.]

When you notice that an iron is not performing as well as it did when it was new you will find that poor thermal transfer from the element to the work is usually the cause. Improper care and maintenance and the lack of a periodic cleaning of the bit's shank can cause a layer of oxides, which will inhibit the transfer of heat through the bit. Always ensure plug style bits are properly seated into the elements before heating the iron. If a bit is not inserted fully into the element there may be a gap behind the bit. This gap can cause a hot spot within the element causing a premature failure of the soldering iron.

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To avoid using abrasives, cleaning with sal ammoniac is recommended. This comes in a block. You rub the soldering iron bit on the surface. As the surface becomes hot, it begins the cleaning process, noted by the smoke rising from the block. When the block under the bit becomes clear, the bit will be clean and can be tinned as above. If this is done at the end of each session of soldering, the bit will last and will be ready for soldering immediately when you next need to use it.

Tinning

Introduction

Proper care and maintenance of your soldering iron bit involves tinning, wiping (and wetting) and also periodic cleaning of the bits shank. These actions are very important and quite simple to perform, but are often neglected. When performed properly they will not only ensure the longest possible working life for your soldering iron bits, but they will also have positive effects on the overall performance of your soldering iron.

Tinning


Tinning may not be necessary if the bit you are using is new and arrives pre-tinned from the manufacturer, or has been used previously and been properly maintained. When a bit does need to be tinned (or re-tinned) it must be clean and free of any surface oxidation before it will accept any solder. Once the bit is properly tinned, care should be taken to prevent bit de-wetting by occasionally cleaning and adding small amounts of fresh solder, especially if the bit is being subjected to long periods of inactivity or idling.

If the bit to be tinned is unplated copper it should be cleaned and dressed with a single cut, flat file. After filing the bit it should be heated in the iron. When the bit reaches the lowest temperature required to melt solder, a rosin core solder should be fed onto the bit. Do not allow the iron temperature to rise too high before applying the solder, because excess heat will cause the bit surface to re-oxidize and no longer accept the solder.

If the bit is plated it should never be filed, or heavily abraded. Care should be taken to ensure the plating is not damaged or removed, as this will shorten the working life of the bit dramatically. When pre-cleaning is necessary for plated bits, they should be cleaned with a mildly abrasive emery cloth and may require an acid flux to remove the oxides before tinning, or re-tinning.

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Wiping the Bit

During use a bright, thin, but evenly tinned surface must be maintained on the working portion of the bit. Oxidation and contaminants must be continually removed from the bit surface to achieve maximum performance. This will help to ensure the proper transfer of heat from bit to work and will eliminate the possibility of impurities being transferred into the solder joint.

Between each solder application simply wipe the working area of the bit clean on a damp cellulose sponge to remove the dross and oxides that will accumulate and add small amounts of fresh solder to the bit as needed. A gentle wiping is all that is required and care must be taken not to over wipe the bit, because oxidation will occur on the surface quite rapidly if all of the solder has been removed. Once this oxidation occurs it becomes difficult, or even impossible for solder to wet to the bit. It then becomes necessary to properly clean and re-tin the bit in order to regain the appropriate wetting action required for adequate performance. When you have finished the soldering application, you should wipe any contaminates from the bit's surface and add a small amount of fresh solder to it before allowing the iron to cool. This layer of solder ensures protection from oxidation of the bit between uses and will help to extend the bit's working life.

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Cleaning

It is important to periodically clean the shank of the plug style bits as well as the inner surface of the element. This is done to keep the bit from seizing in the element and also to keep from building a layer of oxides and contaminates that would obstruct the transfer of heat from the element to the bit. After allowing the iron to completely cool the bit should be removed and the bit shank and inner walls of the element should be wiped clean with a mildly abrasive emery cloth or soft wire brush. This cleaning process should be done as often as needed, depending on the work environment, but not less than once a week.

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Care in the operation of irons

The most important element in the deterioration of soldering iron bits is long idle times. This is where you leave the iron on, and not in use, for a long time.

Have everything ready when you start soldering, so the iron will be used continuously, and will not sit there building up heat, while you get ready to use it again. An idle iron will keep heating to its maximum capacity, and without anything to transfer the heat to, it will start burning off the tinning, after a short while. So if you will not be using the iron for a while turn it off until you are ready again.

The other elements leading to deterioration in performance come from lack of cleaning and tinning of the tip. When the coating of solder burns off or is coated with carbon you get poor heat transfer from tip to working surface making it appear that the iron is not heating properly.

Soldering Ingredients and Methods

The soldering process may be accomplished in a wide variety of ways, but the four primary ingredients required will remain the same. They are; the base metal (or metal items being joined) a type of flux (or a method of cleaning and maintaining the surface to be soldered), the solder and a source of heat. It is important to match the soldering method and the equipment that will be used, to the soldering application that is being considered.

Base Metal


The base metal is the metal that is in contact with the solder and forms an intermediate alloy. There are many metals that will react willingly with solders to form a strong chemical and physical bond, while others can be very difficult, or even impossible to solder.

Flux

Flux is used to eliminate minor surface oxidation and to prevent further oxidation of the base metals surface during the heating process. Although there are many types of flux, each will include two basic parts, chemicals and solvents. The chemical includes the active portion, while the solvent is actually the carrying agent. It is the solvent that determines the cleaning method required to remove the remaining residue after soldering.

Solder

Solder is the alloy used to create the solvent action, which generates the bond between the base metals. The type and form of the solder is very important and must be determined by the individual application being performed, as well as the base metals and soldering method being employed.

Methods

There are several methods, as well as a wide variety of tools available to perform the task of soldering. Some of the current methods that are available include induction, conduction, ultrasonic, flame, dipping, resistance, oven and wave soldering. Some of these methods involve the use of small inexpensive hand tools, while others may require large and expensive machinery, equipment and tools. It is a good idea to become educated on the various methods and tools that are available, in order to insure that you are utilizing the best, safest, most efficient and economical means available for your specific soldering application.

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Soldering

Soldering Materials

Solder

Solder Alloys

There are a wide variety of solder alloys for varying uses as shown by this table below, which also gives the solidification and liquifaction points together with their uses.

Ag = Silver

Cd = Cadmium

Cu =Copper

PB = Lead

Sn = Tin

Sb = Antimony

2%Sn/2%Sb/96%Pb Solidus 305°C Liquidus 315 °C Uses: High Temperature, High Creep Strength

5%Sn/93.5%Sb/1.5%Pb Solidus 296 °C Liquidus 301°C Uses: High Melting Point

95/5%Sn/4.5%Pb Solidus 236°C Liquidus 243°C Uses: High Melting Point

100%Sn Solidus 232°C Liquidus 232°C Uses: Lead Free

15%Sn/85%Pb Solidus 225°C Liquidus 290°C Uses: Lamps

96% Sn/4%Ag Solidus 221°C Liquidus 221°C Uses: Stainless Steel, Bright, Strong Non Toxic

20%Sn/80%Pb Solidus 183°C Liquidus 275°C Uses: Lamps

30%Sn/70%Pb Solidus 183°C Liquidus 255°C Uses: Lamps, Motors

31.2%Sn/67Pb/1.8%Sb Solidus 185°C Liquidus 243°C Uses: Radiators, General Purpose Non Electrical

40%Sn/60%Pb Solidus 183°C Liquidus 234°C Uses: General Purpose

45%Sn/55%/Pb Solidus 183°C Liquidus 224°C General Purpose

50%Sn/48.5%Pb/1.5%Cu Solidus 183°C Liquidus 215°C Uses: Saves Copper Erosion

50%Sn/49.7%Pb/0.3%Sb Solidus 183°C Liquidus 212°C Uses: General Purpose

50%Sn/50%Pb Solidus 183°C Liquidus 212°C Uses: General Purpose

60%Sn/39.7%Pb/0.3%Sb Solidus 183°C Liquidus 188°C Uses: General Purpose

60%Sn/40%Pb Solidus 183°C Liquidus 188°C Uses: Electrical

63%Sn/36.7%Pb/0.3%Sb Solidus 183°C Liquidus 183°C Uses: Electrical

62%Sn/35.7%Pb/2%Sb/0.3%Ag Solidus 179°C Liquidus 179°C Uses: Silver - Plated Surfaces

62%Sn/36%Pb/2%Ag Solidus 179°C Liquidus 179°C Uses: Silver - Plated Surfaces

18%Sn/80.1%Pb/1.9%Ag Solidus 178°C Liquidus 270°C Uses: Aluminium

50%Sn/32%Pb/18%Cd Solidus 145°C Liquidus 145°C Uses: Low melting point, Soldering on Gold

70%Sn/30%Zn Solidus 196°C Liquidus 307°C Uses: Spray Wire for Metal Film capacitors

80%Sn/20%Zn Solidus 196°C Liquidus 268°C Uses: Spray Wire for Metal Film capacitors

30%Sn/70%Cd Solidus 176°C Liquidus 240°C Uses: Low Thermal EMF Solder

Common Solder Compositions for Stained Glass

The table above shows what a large variety of compositions there are for various soldering purposes.

The common solders for stained glass are mixtures of tin and lead, respectively:

63/37: melts at 183°C (362°F)

60/40: melts between 183°C (362°F) and 188°C (376°F)

50/50: melts between 183°C (362°F) and 212°C (421°F)

40/60: melts between 183°C (362°F) and 234°C (454°F)

lead-free solder (useful in jewellery, eating containers, and other environmental uses): melts between 118°C (245°F) and 220°C (428°F), depending on composition.

The 63/37 and 60/40 solders are most often used in copper foil work because of their narrower melting range. This allows the solder to set more quickly than the solders with higher lead content. They tend to give smoother beads also.

 50/50 and 40/60 solders are more often used in leaded panel work. Their wider range of melting temperatures allows the solder to spread and become flat.

Hard Solder

As used for brazing, hard solder is generally a copper/zinc or copper/silver alloy, and melts at higher temperatures than tin/lead compositions.

In silversmithing or jewellery making, special hard solders are used that will pass assay. They contain a high proportion of the metal being soldered and lead is not used in these alloys. These solders also come in a variety of hardnesses, known as 'enamelling', 'hard', 'medium' and 'easy'. Enamelling solder has a high melting point, close to that of the material itself, to prevent the joint de-soldering during firing in the enamelling process. The remaining solder types are used in decreasing order of hardness during the process of making an item, to prevent a previously soldered seam or joint de-soldering while soldering a new joint. Easy solder is also often used for repair work for the same reason. Flux or rouge is also used to prevent joints de-soldering

Flux Core Solder

A tube of multi-core electronics solder is used for manual soldering in the electronics industry - the flux is contained in cores within the solder itself.

Solder often comes pre-mixed with, or is used with, flux, a reducing agent designed to help remove impurities (specifically oxidised metals) from the points of contact to improve the electrical connection. For convenience, solder is often manufactured as a hollow tube and filled with flux. Most cold solder is soft enough to be rolled and packaged as a coil, making for a convenient and compact solder/flux package.

The two principal types of flux are acid flux, used for metal mending; and rosin flux, used in electronics, where the corrosiveness of the vapours that arise when acid flux is heated could damage components. Due to concerns over atmospheric pollution and hazardous waste disposal, the electronics industry has been gradually shifting from rosin flux to water-soluble flux, which can be removed with de-ionised water and detergent, instead of hydrocarbon solvents.

Lead-Free Solder

Most of the advice in the stained glass community about lead free solder is to avoid using it. However, lead-free solder is essential for making jewellery (which may have skin contact) or any project that may be in contact with food.

Lead-free solder does require a hotter iron than lead bearing solders, plus it does not flow easily. It has a pasty state between solid and liquid that is prone to lumps and spikes. If this is not bad enough, it also does not take patina designed for lead bearing solders well.

Those using rheostats with their soldering irons, should get rid of the rheostat, as they limit the ability of the iron to recover the soldering temperature. The best iron to use with lead free solders is a temperature controlled iron of 100W or 200W. You can get tips that run at 800F to replace the standard 700F tips. This helps with the higher temperatures needed for the lead free solder. But you should not be vaporizing the solder as the fumes are a health hazard.

Consider the effects of the flux that you are using. Experimenting with various kinds (see below) can lead you to one that works better than the others.

As always, good hygiene and good ventilation are required when soldering. Also you should wash your hands well and frequently, and eat in a separate room.

Flux

An Introduction

Flux is a key contributor to most soldering applications. It is a compound that is used to lift tarnish films from a metal's surface, keep the surface clean during the soldering process, and aid in the wetting and spreading action of the solder. There are many different types and brands of flux available on the market; check with the manufacturer or reseller of your flux to ensure that it is appropriate for your application, taking into consideration both the solder being used and the two metals involved in the process. Although there are many types of flux available, each will include two basic parts, chemicals and solvents.

The chemical part includes the active portion, while the solvent is the carrying agent. The flux does not become a part of the soldered joint, but retains the captured oxides and lies inert on the joint's finished surface until properly removed. It is usually the solvent that determines the cleaning method required to remove the remaining residue after the soldering is completed. It should be noted that while flux is used to remove the tarnish film from a metal's surface, it will not (and should not be expected to) remove paint, grease, varnish, dirt or other types of inert matter. A thorough cleaning of the metal's surface is necessary to remove these types of contaminates. This will greatly improve the fluxing efficiency and also aid in the soldering methods and techniques being used.

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The Action of Fluxes

All common untreated metals and metal alloys (including solders) are subject to an environmental attack in which their bare surfaces become covered with a non-metallic film, commonly referred to as tarnish. This tarnish layer consists of oxides, sulphides, carbonates, or other corrosion products and is an effective insulating barrier that will prevent any direct contact with the clean metal surface which lies beneath. When metal parts are joined together by soldering, a metallic continuity is established as a result of the interface between the solder and the surfaces of the two metals. As long as the tarnish layer remains, the solder and metal interface cannot take place, because without being able to make direct contact it is impossible to effectively wet the metal's surface with solder.

The surface tarnishes that form on metal are generally not soluble in - and cannot be removed by - most conventional cleaning solvents. They must, therefore be acted upon chemically, or mechanically, in order to be removed. The required chemical reaction is most often accomplished by the use of soldering fluxes. These soldering fluxes will displace the atmospheric gas layer on the metal’s surface and upon heating will chemically react to remove the tarnish layer from the fluxed metals and maintain the clean metal surface throughout the soldering process.

Chemical reactions


The chemical reaction that is required to remove the tarnish layer will usually be one of two basic types.

It can be a reaction where the tarnish and flux combine forming a third compound that is soluble in either the flux or its carrier.

An example of this type of reaction takes place between water-white rosin and copper oxides. Water-white rosin, when used as a flux is usually in an isopropyl alcohol carrier and consists mainly of abietic acid and other isomeric diterpene acids that are soluble in several organic solvents. When applied to an oxidized copper surface and heated, the copper oxides will combine with the abietic acid forming a copper abiet (which mixes easily with the un-reacted rosin) leaving a clean metallic surface for solder wetting. The hot molten solder displaces the rosin flux and the copper abiet, which can then be removed by conventional cleaning methods.

Another type of reaction is one that causes the tarnish film, or oxidized layer to return to its original metallic state restoring the metals clean surface.

An example of this type of reaction takes place when soldering under a blanket of heated hydrogen. At elevated temperatures (the temperature that is required for the intended reaction to take place is unique to each type of base metal) the hydrogen removes the oxides from the surface, forming water and restoring the metallic surface, which the solder will then wet. There are several other variations and combinations that are based on these two types of reactions.

Flux as a temporary protective coating

Once the desired chemical reaction has taken place (lifting or dissolving the tarnish layer) the fluxing agent must provide a protective coating on the cleaned metal surface until it is displaced by the molten solder. This is due to the elevated temperatures required for soldering causing the increased likelihood that the metal’s surface may rapidly re-oxidize if not properly coated. Any compound that can be used to create one of the required types of chemical reactions, under the operating conditions necessary for soldering, might be considered for use as a fluxing material. However, most organic and inorganic compounds will not hold up under the high temperature conditions that are required for proper soldering. That is why one of the more important considerations is a compounds thermal stability, or its ability to withstand the high temperatures that are required for soldering without burning, breaking down, or evaporating.

When evaluating all of the requirements necessary for a compound to be considered as a fluxing agent, it is important to consider the various soldering methods, techniques and processes available and the wide range of materials and temperatures they may require. A certain flux may perform well on a specific surface using one method of soldering and yet not be at all suitable for that same surface using a different soldering method. When in doubt it never hurts to check with the flux, or solder manufacturer for recommendations.

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Flux Categories

A. Rosin Fluxes

Rosin based fluxes are made from rosin which is extracted from pine sap. The purified product is known as "Water White Rosin". The active ingredient is an organic acid, abietic acid and may contain homologues such as dehydro abietic acid and leviopmaric acid.

In addition to rosin other activators may be present at different levels to increase the ability to clean and de oxidise. Activators are compounds that decompose at soldering temperatures yielding ammonia or hydrochloric acid in the process. Flux activity is categorised as R (rosin only), RMA (rosin mildly activated) and RA (rosin activated). A low boiling solvent such as isopropanol is used as the vehicle so they are flammable.

Type R containing only rosin is the least active and is recommended for surfaces very clean to start with. It leaves virtually no residue behind. Thus this is the best rosin based flux for copper foil and lead cames.

Type RMA contains a small amount of additional activator to enhance cleaning and de-oxidisation leaving only a minimum amount of inert residue behind. A characteristic of RMA fluxes is that the remaining residue be non-corrosive, tack free, and exhibit a high degree of freedom from ionic contamination after cleaning. These fluxes are acceptable, but more difficult to clean. They are not acceptable for conservation work.

Type RA are most active of the rosin fluxes, and leave the most residue, however the residues can be removed with appropriate flux cleaners. The residues are really difficult to remove in decorative glass work circumstances and should not be used.

B. Water Soluble Fluxes

These are called water-soluble, as the residue left after soldering is water soluble, although the flux is not. The so-called water-soluble fluxes are divided into two categories, organic and inorganic based on composition. Organic fluxes are more active than RA rosin, and inorganic are the most active of all. Both of these are the best of all fluxes to use in decorative glass work, as the residues are water soluble making clean-up easier, and they are more effective in wetting and keeping the copper and lead free from oxidisation at soldering temperatures.

Other articles in this series are:
Processes
Tools

Soldering Techniques

Soldering Techniques 

Soldering - how it works

Soldering is a well known and widely used process where two or more metal items are joined together using a fusible alloy with a melting temperature that is lower than their own. The most commonly used solder is a fusible alloy consisting essentially of a tin and lead mixture.

The solder actually dissolves a small amount of the metal’s surface, at a temperature that is well below its melting point and joins with it. It is this solvent action of the solder alloy that causes it to fuse with and attach to the surface of the metal items being joined.

The solvent action that takes place, between the solder and the metal, makes the joint chemical (not just physical) in nature and causes the properties of the joint to differ from the original solder’s properties and from those of the surface of the metal items being joined. When metal parts are joined by solder, a metallic continuity is established as a result of the interfaces where the solder is bonded to the metallic surfaces.

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Soldering vs. Welding

The metal joining process that is generally referred to as soldering (or soft soldering) requires temperatures between 183 to 445°C. The joining of metals at temperatures above 445°C (and below the melting point of the metals being joined) is more commonly referred to as brazing (or hard soldering). The actual melting and fusing of the metal items that are being joined together is considered welding. There are, of course overlapping situations that may occur when classifying a process.

The actual joining characteristics that take place are physically different in each of these processes. Soft solders attach to metals by what is referred to as a solvent action that takes place at relatively low temperatures. Hard solders, or brazing alloys contain metals that require higher temperatures to cause the solvent action to take place and fuse the alloy with the metal being joined. Because welding involves actually melting and fusing the surface of the metals that are being joined together, a filler, or fusible material is not always used.

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Creating a Quality Solder Joint

Soldering is the process that uses solder (a metal alloy usually consisting of tin mixed with other metals) for the metallurgical joining of metal components to form an electrical, mechanical or hermetically sealed bond at temperatures (less than 449°C) that are well below the melting temperature of the individual components that are being joined. The soldering equipment used to create the required heat and other materials (solder, fluxes, heat sinks, fixtures, etc.) should always be properly matched to the intended soldering application. The equipment and materials used may vary, but the basic soldering techniques that are required will usually remain the same.

One of the most important rules to remember about soldering is "keep it clean". This includes, not only the items being soldered, but also the materials used. Choose quality solders and fluxes without unnecessary impurities. Surface oxidation, contaminants and other impurities are some of the most common reasons for poor quality solder joints. The use of fluxes does not eliminate the need for pre-cleaning the surfaces you are joining, especially if heavy oxidation or large amounts of grease, oil or dirt are present. The stages of soldering are:

Clean: Thoroughly clean all surfaces to be joined, removing any dirt, grease, oil, oxidation, paint, coatings or other impurities that may exist before attempting to solder. Proper wetting can only occur when the intended solder joint area has been properly cleaned. Soldering should be performed as soon as possible after cleaning to eliminate the possibility of re oxidation or contamination of the items being soldered. [So leaving pieces fluxed overnight is not good practice. Flux only the area that can be soldered in the next few minutes.]

Flux: Apply flux sparingly to each of the intended joint surfaces. Flux is primarily used for the removal of light oxidation and to protect against re-oxidation during the actual soldering process. Make sure you have the right flux for the application being performed.

Heat: Apply heat directly to the intended joint area. The correct application of heat is important and should be consistent with the operating requirements determined by the type of equipment being used. Fast and accurate heating will minimize the risk of thermal damage.

Solder: Add solder to the heated surfaces you are joining (do not apply solder directly to the tip, or other heat source being used). The solder should flow uniformly over all of the surfaces that are being connected. Stop feeding solder as soon as you have applied an adequate amount and then remove the heat source. The amount of solder is important because too much will create unnecessary waste, while too little can affect the mechanical strength and conductivity of the finished solder joint.

Cool: Allow the finished solder joint to remain undisturbed until it has completely cooled. You should never attempt to speed up the cooling process by blowing on the solder joint. Even minor vibrations or disturbances during cooling, can cause micro fractures or other types of damage that may severely weaken the solder joint.

Inspect: Check all finished joints for proper wetting, the right amount of solder, a good physical appearance, and the required mechanical strength.

Skills


A quality solder joint is not achieved solely by the equipment and techniques being used, but also by the operator being trained to use them properly. An operator should know how the physical appearance of a finished solder joint helps to determine possible flaws that may exist.

A quality solder joint appears bright, shiny and smooth with all components appearing well soldered. The surface of a finished joint should never look rough, grainy, dull, or flaky (these are signs of what is commonly referred to as a cold solder joint). Problems with proper wetting (solder balling up and not adhering to the components surface) are sometimes associated with too much heat, but are more often related to cleanliness issues.

Courtesy of American Beauty Tools

Exhausting Soldering Fumes

Making a fan


Exhausting fumes while soldering is a safety issue of some importance. If you happen to have an outdoor screened-in studio a simple fix can be had with a computer fan You can scavenge such a fan from an older used computer ready for disposal. Simply cut four timbers 50mm square or 25mm x 100mm to fit around it as a box. Attach a long electrical cord to it with an approved plug;. Attach a screen to both sides. Plug in. An additional feature is to attach an activated carbon filter (as used for cooker hoods) to the front of the fan. This removes particles and some fumes.

Positioning

Always set it to draw fumes away you, generally pointing it so that it is blowing the fumes in the same direction as the larger air flow in the studio. In general a very large fan doesn't always do the job alone, since the fumes always seem to rise up and find your nose. However, with the additional tiny computer fan sitting right next to where you are currently soldering, the fumes just move away.

Other articles in this series:
Materials
Tools

Leading Basics

Leading up boards

It is often best to have a separate board to place on top of your bench to do the leading. This means that you can move the project if it has to be delayed while having to do something else.

Start with a work board that is thick enough to be relatively rigid, but is easy to put nails into. Plywood is a good, but relatively expensive board. MDF is heavy and difficult to put nails into, so avoid it.

You can either have two permanent battens of wood about 19 mm thick attached at right angles to each other in one corner, or you can attach them to the board as required for each project. The permanent placement means you do not have to check the accuracy of the right angle each time you use it, but it does not allow easy adjustment for smaller or larger pieces than the battens will accommodate. The temporary solution requires checking the right angle each time you use it, but it allows you to place the battens over the cartoon at the appropriate distance from the battens without cutting the cartoon or making multiple checks of the accurate placement of the cartoon.

The battens should be attached to "base" board about 60 mm in from the edge to have a little work area to cut leads, etc. They need to be a little longer than the dimensions of the pattern you are assembling. 

Corner battens nailed down over cartoon and perimeter leads placed

If you are putting the battens on top of the cartoon, you can use the cut lines to align your battens. Cut two short pieces of the came you are using for the edge. Centre their hearts on the cut line and butt the battens against them. Nail or screw the batten in place. Repeat for the other side. 

Using piece of came to set the perimeter batten

If you are using permanently fixed battens, place the cartoon, which has been trimmed to the outside lead line on two sides, against the wood strips. Use some horseshoe nails or tape to hold the pattern in place. Check to ensure the correct distance has been maintained between the battens and the cut lines on the cartoon. Adjust as necessary.

Establishing the Perimeter for a Window

The first thing to be established about the panel is the placing of the came that goes around the edge of the panel.

Make a straight cut across the outside came and put that trimmed end into the corner and along the vertical wood strip. The lead should be longer than the leading cartoon to accommodate the length of the upper horizontal. If it is even longer than required, the extra can be trimmed off after soldering. 

Came butted at corner

Next butt a trimmed piece of perimeter came along the horizontal wood strip. This one should be shorter than the cartoon. It should be shorter by half the width of the perimeter cames to allow the vertical came to butt against it. An easy way to do this is to use a short piece of the appropriately sized came. Place the heart on the cartoon cut line and next to the perimeter came. Use you lead knife to extend the inside of the came across to mark the perimeter came. 

setting for cutting the bottom perimeter came to length

Placing a piece of came to set the line for cutting

The reason for having the vertical cames running from bottom to top is that there is a fraction more strength in the heart of the came going all the way to the bottom of the panel, rather than resting on the flanges of the came.

These perimeter cames should be held in place with horseshoe nails. Try placing the nails only where a lead line will be soldered in order to cover any nicks the nails might make. Alternatively, you can place the nails at the ends of the perimeter cames to keep them from sliding vertically or horizontally.

Straightening the Came

Before using the came it is important to straighten it. This increases the stability of the came during the leading process. Most often nowadays, you use a lead vice. This operates similarly to a cleat on a sailing boat. The more strain that is applied, the tighter the vice grips the came.

You place the end of the came into the vice so that the came appears at the back of the vice. Give the top of the vice a firm tap with your pliers to set the teeth into the came. Grasp the other end of the came with the pliers, and put one foot behind you to brace yourself if the came does slip out of the vice. Draw the came toward yourself until you can see the lead is straight and any kinks have straightened. 

Short piece of came being straightened with lead came vice and pliers

Take the came out of the vice and keep it straight. You transport it by grasping each end and keep the came under tension until you get it to the destination. It is often easiest to cut the full length in half before moving it, as it will not then be longer than your arms can stretch.

Remember, this process is to straighten the came to give pleasing lines in the leaded panel. It is not stretching the lead. Stretching the came can weaken the lead.

Dressing the Came

This relates to how easy it is to slide the glass into the channel of the came and nothing about your clothing.

If you have consistent difficulty in sliding the glass into the came, you should consider dressing the came before use. Dressing the came consists of running a fid or other hard material along each of the four flanges of the came. In doing this, you are pressing each flange down against the bench or other smooth surface. 

Pressing the came flange down with stopping knife.  Each of the four flanges need to be treated in this way

Dressing the cames gives a slight bevel or ramp for the glass to slide over the edge of the came and into the channel of the came. You can dress the whole length at once, or as you cut the pieces off from the main length. Dressing shorter pieces is less likely to bend the came away from the straight.

Of course, it is not enough just to dress the came at the start. There is an analogous procedure after the whole panel has been leaded, soldered and cemented.

In this instance the term ‘dressing the cames’ means to close or bend the leaves/flanges of the came toward the glass. This is done after the soldering and cementing is complete. It provides a neat rounded appearance to the lines, traps the cement you have already added, presents less area for the rainwater to collect, and makes polishing easier. It is also the time when you may break the glass by putting too much pressure on the glass, so be careful!

Dressing the cames at the finishing stage is done with an oyster knife or fid. It is often best to avoid metal and better to use wood sticks or plastic tools. The pressure is placed on the came rather than the glass. Run the fid lightly at a shallow angle along each flange of the came. It is helpful to use a finger of your other hand to guide the fid along the cames. You may want to do this several times, as repeated light pressure will cause the flanges of the came to move gently toward the glass with less risk of breaking the glass. This can only be done while the cement is pliable. If it is done after polishing, you will need to re-do the polishing, as it will make the edges of the came silvery rather than shiny black.

Cutting Lead Came

Cutting came is a gentle process rather than an abrupt chopping effort.

There are at least three kinds of implements in common use to cut lead came. 

Clockwise from the top: curved blade (pro), straight blade, lead dykes or nippers

Lead nippers or lead dykes

Lead nippers/dykes are a kind of adapted side cutters, used for cutting wire and by electricians. But leaded glass dykes have the bevel only on one side of the jaws, making them almost useless for anything other than cutting lead. This arrangement only crushes the lead on the cut-off side and also leaves a minimum of lead next to the back of the jaws.

To use them the jaws of the dykes are aligned in the same angle as the heart of the lead, cutting across the leaves of the lead. They do not cut from the top and bottom of the came. These are very quick for right angle or very oblique angles on the came. However they are of little use for acute angles.

Lead knives

For more acute angles, blades are more commonly used. These can be either straight edges or curved blades. The straight edge lead knives are essentially putty knives or stiff scrapers sharpened to an acute angle. This kind of knife is normally wiggled from side to side while applying pressure to work through the came.

Other knives are curved to make rocking back and forth easier. There are a variety of knives such as the Pro or Don Carlos. Some look more like a scimitar than a lead knife! These are used to rock along the line where you are cutting the came.

What ever kind of knife you are using, be sure to be directly above the knife, looking along the blade to ensure vertical cuts.

Saws

Of course, saws are sometimes used. The blade needs to be coarse toothed to enable the soft lead to drop out of the teeth. These saws can be hand held or table saws. Normally, it is quicker to use lead dykes or knives. However, if you are in production mode, a powered table saw may be worthwhile.

 Leading Procedure

Cut the leads exactly as the cartoon indicates. In other words, where one lines runs into another, that is generally a stopping/starting point for the came.

Always lead to the cartoon line, not the glass. This ensures accurate completion of the panel. If the glass is slightly too small, the cement will take up the gap (assuming the flange of the came covers the glass – if not, you need to cut another piece of glass that fits). If the glass overlaps the cut line, it needs to be reduced.

Placing gauge for cutting to length

Cut the ends of the came shorter than the glass. The best way to determine the extent of this is to place a piece of came of the dimensions being used for the next edge on the cut line. Use it to determine the length and angle for the cut. The object is to have each piece of came butt squarely against the passing came, to make a strong panel and to make soldering easier. 

Marking the came for cutting to length

Testing the length of the came

Leading the first pieces

After establishing the perimeter cames, place the first glass piece into the corner formed by the perimeter cames. Normally, you will be working from the lower left corner toward the upper right corner of the pattern if you are right-handed. The reverse is the case for left-handed people. Hold each piece of glass in place with some scrap lead and nail. The scrap lead will prevent the nail from chipping the glass. It's important all glass is held in place with nails so no shifting occurs while working in another area of the panel.

Fitting the Glass to the Cartoon

Often you find that the next piece of glass does not fit properly. Possibly it rocks a bit in the came’s channel. Possibly it is simply just a little too big.

Glass too wide and slightly angled along the long line

The first thing to do is to take the previously placed piece of glass out and remove the came, to ensure the previous piece of glass is not too large. The glass should not overlap the cut line. If you have drawn your cut lines to 1.2 mm you should see only the faintest line of paper between the glass and the dark cut line. 

If the glass seems too large, check that it is firmly in the channel of the previous came, as sometimes the glass catches on the edge of the came and does not go into the channel.

The next check is to determine whether the apparently too large piece of glass really fits the cartoon cut lines. Place the glass inside the cut lines. You should see a faint line of paper between the glass and the cut line.

When you are sure both pieces of glass are the correct size, put the came back between them and check again. If the glass is still too large, make sure the came butting onto the came separating the glass is not too long. This is a common reason for lead panels to grow beyond their initial dimensions.

If the glass is the correct size and the butting cames are correct, replace the came. Put the too large piece of glass into the came and position it so it has the best fit to the next cut line. Take a felt tipped pen and run it along the edge of the came, marking the large piece of glass. 

Marked glass with nail pointing to area too wide that needs reducing

Take it out and check on where the line is farthest from the edge of the glass. That is where you need to reduce the piece. 

Snugging the came to the glass

It is important to have the came fit snugly to the glass (assuming the glass to be the right size and shape). If it does not, the panel is likely to grow beyond the intended dimensions.

To ensure the came is tucked snugly against the glass, you use a fid of firm material (wood or plastic, for example) to press against the heart of the lead. You can press directly toward the glass, or make multiple passes along the length of the came to ensure the heart is touching the glass all along its length.

You should avoid steel tools, because you may cut the lead, and if the blade is wide you will not find it easy to fit along all of the curves.

Following all these steps in the process of leading should lead to quickly and accurately assembled panels.