Post by koolbraider on Jun 15, 2012 10:25:03 GMT -6
Wasn't sure how to describe this, and I seem to remember a bit about this on the old forum: spots on copper that won't take LOS. I sand, clean very carefully, etch, dunk in baking soda water, clean with ammonia and soapy water, and draw a design. The last two disks have given me problems. I tried completely removing the LOS with "Penny Brite" or whatever it's called; more cleaning; LOS again and still spots!! I'll probably throw the last one away since I think it's a lost cause. This didn't happen last year and the disks are from the same source. HELP!!!
I don't know what causes that, but I've had it happen with wire too.
Most of it oxidizes nicely, yet a few shiny areas are left behind. One time I LOS'd a pair of earrings and the LOS didn't touch them - still bright and shiny when they came out. It wasn't coated wire either - wire from that same spool oxidized perfectly.
I don't know what causes it or how to fix it, but I wouldn't throw it out. My metal instructor would say it's a design opportunity. Figure out how to use it or let the spots be part of the design. Someone will think it's cool and want it.
Post by koolbraider on Jun 30, 2012 9:47:29 GMT -6
Well, I took pics of blanks with dark spots and hope to post them soon. I did rescue one disk and left it non-LOS'd and it does look very nice. You have to get it in the light and hold it just right to see the problem.
I have a cuff blank that I had prepared with nail polish on the back as usual. At that stage I no longer touch the bare surface. I had stored that one in a regular baggie and it has developed a couple of nasty spots, but the non-treated ones that are still in their original bag are perfect. There may still be a coating of oil on them to prevent spots? I did a bit of research and found that polyvinyl chloride can cause contamination on copper (took a long time trying to come up with the right combination of search terms for that one).
Yes, the copper was from the same supplier I've ordered from several times before and have never had this problem. But I did decide to buy a few from a supplier on Etsy and so far those seem fine. This decision was also an economic one since the minimum order amount was a bit steep for me.