Gold test link

Hallo, I'm not find the link about gold test. I have nitric to test.
for example, this scrap epson or this object that I don't know the name which after I dismantled it I found inside this gold foil.

Just put a drop of nitric on a surface you suspect is gold plated. The nitric dissolves the base metal below the gold foil and the gold can be observed, it's easier if it is washed into a small beaker or spot plate. This isn't a 100% sure test method as there could be some surface treatment that would resist nitric and look like gold but it gives a really good indication of what you have and how thick the plating is.
If you want to be really sure, wash the foils in a small beaker with some water and let it settle, then decant the water and add a drop of hydrochloric acid. If you don't wash it too well the traces of nitric still in on the foils is enough to dissolve the gold and the solution can be tested with stannous.

If you haven't read about stannous testing yet you should do it. I leave that part as an exercise, it's been described many times on the forum and in Hoke's books so you should be able to find out about it easily and learn some extra on the way.

While you are at it, read up on "gold from black chips" and "bond wires", that is where most of the gold is on that card.

The card you have is a dot matrix printer and the strange epson thing is the print head with it's hammers and was made made by Epson.

Göran

Thank you Goran.
Luigi