Black and copper powder in filter

[Jeff0172]

I did a batch of silver the other day and after i cemented the silver i went to go filter it and golt this black and copper powder any idea what could cause this? Ive never had this happen so any information would be greatly appreciated

 

[Palladium]

When you cemented on copper did you notice any red fumes?

 

[Jeff0172]

No not that i noticed there where no fumes the only thing i did diffrently was i cemented the silver out filtered it then about 4 days later i filtered it again with vacuum filtration to make sure i got all the silver and this is the result from the vacuum filtration my last batch i did get about a ounce of black powder also it didnt test as silver so i put it aside these last 2 batches where broken antique jewelry so im not sure of the alloy other then silver

 

[nickvc]

We need more details to even try to answer your question, what did you dissolve ?

 

[Jeff0172]

These last 2 batches where broken antique jewlery the nitric i used this time was a little stronger so i added a little less then a normally do for a 2000ml batch

 

[g_axelsson]

It could be iron hydroxides from springs and hinges. If the pH goes too high iron will precipitate as brown rust.

Göran

 

[Jeff0172]

I think you may be right i cut the clasps off and save them for later just because of that but this batch i forgot to. is there anyway to get rid of the iron? Ive never dealt with this issue before so any information would be appreciated

 

[g_axelsson]

What are you going to do with the silver powder? If you are going to melt it then the iron will collect in the slag.

Alternatively, washing with dilute hydrochloric or sulfuric acid should dissolve the iron.

Göran