If you did happen to change from HCl and went to nitric with the hope of washing powder without dissolving gold, you would have to incinerate between these, rinsing will not remove the chlorides, water may remove some table salt and if it was boiling hot may remove some lead chloride, but you could still have enough chloride salts to make aqua regia, and dissolve some gold, neutralizing and washing then incineration would prevent the gold from dissolving.
I do not see a reason to change to nitric at this stage, and some of these white salts it is very possible they would not be soluble in nitric acid any way (like AgCl).
Let salt and foils settle well and decant solution, then wash out the chloride salts with boiling hot water keeping it hot while letting foils settle before decanting the wash from the foils, filtering may be needed at some stage but I would avoid filtering if not necessary, if you do use filtering you can wash the foils into a jar with a spray water bottle and a funnel.
Some types of white salt:
NaCl, soluble in water,
CuCl is soluble in HCl,
PbCl2, soluble in boiling hot water,
AgCl, soluble in ammonium hydroxide,
(Caution make sure to acidify any liquid, or solution you decant from this ammonia solution, also acidify any powder or foils with HCl acid which come into contact with ammonia compounds (which will precipitate AgCl again), so as not to form a dangerous possibly explosive compound when dry), I also keep ammonia solutions out of my regular stockpots or waste stream. (If I had no plans for reusing the ammonium chloride), the waste is treated separate, so as not to cause any trouble later.