I attended a glass on copper class a few years ago that had ordered fine silver wire from Rio Grande and discovered they were sent sterling.  I can't say this is what happened to you...but their sterling wire did exactly what yours did...turned black with each firing.

Thanks for the replies.  I'm going to anneal the wire and then pickle it, just in case there is some kind of residue on the wire.  If that doesn't work, I'm going to email Rio to ask if it's possible that the wire is sterling.

Please use fresh pickle.

there is no reason for fine silver cloisonne wires to turn black. especially after firing. i would return it to rio and get a refund. I had one of Rio's Tech problem solvers in my pre conference workshop. his name is Phillip Scott. call rio and ask to speak to him, as he would want to know about this problem. his email is pscott@tbg.riogrande.com. tell him i said "hi".

Thanks, Ricky.  That's what I was thinking, too.  I've annealed and pickled at least half of this wire, and used a bunch of it, so I'm not sure if they will refund me for the entire thing, but I will bring it to their attention for sure. 

until recently rio sold silver from their sister company academy. In the past several years that company has been merged twice. try calling here 800-854-8595 and telling them. that is in albuquerque, down the street from rio. Amy is the sales manager, or was when that branch was independent.

I got this email today, as well as a phone call from Phillip Scott:

Hi Roberta,

I did a little research and had some of the product tested and found out that this did come in as sterling silver instead of fine silver.

We have pulled it from inventory and isolated it and are now waiting for the new product to arrive from the vendor. It is expected in the middle of next week.

When the new product comes in we will have it tested to ensure that it is fine silver. As soon as it comes in, I will rush a replacement out to you.

Thanks again for your letting us know so we can fix this.

Best regards,

Phillip Scott

Technical Support

Rio Grande

Thanks for your suggestions and help, everyone! (Especially Ricky, for the very specific advice.) I probably would have just assumed I was doing something wrong and avoided buying more cloisonne wire from Rio if I hadn't put this out there. I'm happy.

fantastic. Phil was great to have in my workshop and incredibly helpful problem solving some of the kiln issues in other studios. Glad you've got it worked out. my own personal advice regarding cloisonne wire is to order it made to the specs you want (height and width of the wire). Hauser and Miller does this for me. 

Hello.  I recently bought some fine silver cloisonne wire from Rio Grande, and I'm unhappy with its performance.  I've done cloisonne work in the past, and the wires are always a nice white colour after firing.  When I fire this new batch, it ended up having a black coating all over the wires.  I checked to make sure the wires weren't melting and sinking into the base, so I know that's not the issue here.  I ended up taking a burnisher to the wires to polish them up after the piece was finished, but I'm still unhappy with the black stuff.  I wonder if a mistake could have been made in manufacturing and they used a sterling alloy instead of fine silver?  I bought quite a bit of wire.  Any ideas?