[KBriggs]

I recently made some AgCl electrodes by making silver wire positive with respect to a gold electrode in 10% HCl. the gold wire now has a greyish coating on it. Is this a layer of silver, or something else?

[NobleMetalWorks]

I recently made some AgCl electrodes by making silver wire positive with respect to a gold electrode in 10% HCl. the gold wire now has a greyish coating on it. Is this a layer of silver, or something else?

If your reaction didn't immediately create a thin layer of AgCl on the cathode, I might be led to believe that some silver oxidized at the anode, accumulated in solution and perhaps deposited om the cathode.  But since the AgCl is created directly on the Ag anode, I don't think that's the case.

Was the gold cathode wire gold plated?  And if so what was it's base metal?

Were you using DI water?  If not, if you were using tap water, you might have fluoride, chlorine or other minerals etc in your water.

Did you use Scientific grade HCl?  Or did you use the industrial version?  You state your electrolyte solution was 10% HCl, is that 10% of 35% HCl?  Or 10% of 15% HCl?  Or a total of 10% figuring for the percentage of the HCl?

A little more information might help someone to answer your question better.

Scott