Thursday, July 25, 2013

It's a mystery!

Today I fired five more pieces of fine silver, thinking I could make a few more pieces for the Oil Heritage Craft Sale this weekend.  The pieces were fired as usual, 1470 degrees for forty five minutes.  They came out of the kiln looking white  (as usual.)  I brushed the silver to let the shine show through (as usual.)  

Then I threw them in the magnetic tumbler (as usual.)    This is where "the usual" ends.  The first two pieces were in the tumbler about ten minutes before I tossed in the other three pieces.  Five minutes later I took out the first two pieces....... all shiny and silver.  Twenty minutes later I took out the other three pieces and saw something I've never seen before.  And, for which I have no explanation.  

The top left piece came out looking like a piece of copper.  The top right piece is a combination of dark copper, magenta and  blue.  The left bottom piece is a light gold color and the right bottom piece is the typical silver color (as was the other piece that went in first.)  

Most of the pieces are the colors I would expect after dipping them in Liver of Sulfur (not after taking them out of the tumbler.)  Somehow my shot has been contaminated but it is so strange that two of the five pieces in the same tumble batch are okay.  

So now I have to clean my tumbler with flat coca-cola and try it again.  I plan on re-firing the pieces to remove the coloring as they did not polish up well at all.  (Obviously they won't be ready for this weekend's sale.)  

This is a mystery to me and one I hope to solve.   


Anonymous said...

Do the color changes correlate in any way to the order in which you brushed them?

Perhaps: silver color first, then the darkest coloration and moving down to the lighter as time went on? With something happening re the brush in between that started to wash out again over time? With this inconsistency, I'd be inclined to blame the brush before the tumbler.

(Either that, or the reverse coloration, due to some deposit building up from the brushing water?)

As to re-firing, have you tried just using a torch? That shouldn't take toooo long....

Alice Walkowski said...

Didn't really pay any attention to the order in which they were brushed, so I can't make a judgement there. I plan on cleaning everything that was used in contact with these pieces though. Don't like that kind of surprise.

Zoe Nelson said...

That is really strange. I've never seen anything like it, so be sure and post how it turns out.