Soldering Interruptions

Do you have to finish soldering/cleaning all in one go? 

Interruptions in soldering are possible, but they should not be long. The flux is an acid and will affect the copper foil. The acid although mild, will began to cause enough corrosion to make further soldering difficult after a few days or a week. If the recommenced soldering is not working as previously, the flux needs to be cleaned off and the oxidisation layer removed from the foil. The easiest way is to use fine steel wool and carefully polish the foil with it. Then flux the area you think you can accomplish in the time you have.

If there is likely to be a significant time before soldering can begin again, clean off the flux and finish with a neutralising compound, or a solution of baking soda. Dry and cover with a plastic sheet, or if small enough, put it into a sealable plastic bag.

If it is a big job in relation to the time available, only flux what can be achieved in that time. This saves clean up time. Although it may be necessary to polish a thin layer of corrosion from the foil before resuming the soldering.