Hi Charlene,
The counter enamel if not seen can be any old mix of swept up colors, not mixing dirt and different COE or leaded with unleaded. It does not have silver in it. It's structural. If seen of course you want a pretty, single color.
Hi, just looked again and saw your first question. Do you neutralize the acid in your copper after etching? possibly it is reacting with the enamels?? just a thought. I do some old lead-based enamels from Thompson, using them up, and also the newer unleaded on my champleve etched and basse taille etched copper. I do find a too-thin coat of flux will not quite cover the raised edges, and can burn out on a firing to fully clear it. Try covering the ridges well, not just a light sift. I have had to stone/sand off such places sometimes. A good deep etch is a challenge to cover well. I tend to really cover it, and fire hot/long to get what I want. Do some tests with same depth you are having issues with.
I think it is not a good idea people to say you must it at xxx temperature, and yyy minutes firing. The firing temperature and the -time depends on the size of the workpiece its thickness, the trivet size, the kiln-brand and the kiln-size the enamel-brand and/or melting point of the enamel . The best is you keep an eye at the firing, and remove the workpiece at once from the kiln, if the enamel-surface is glossy and flat molten. Wear eye-protecting-glasses.
edmund
Hi, Edmund is right, there is no recipe but you need to observe, and adjust. It takes lots of experience to do the firing reliably...best way may be doing a lot of test tiles of your colors, and the ways you may want to layer them..by watching for the moment of just right gloss and flat...you are ready to open door and remove. I use my new thermocouple on my old kiln to get a better cue on ready to go in. THEN I use a timer to remind me to look before it's time to remove. ( I get distracted by another small task,then burn out happens!!) Also, my nice hot fire to clear can just normally produce some 'imperfections" like a burned spot. but I need the clear more than I dislike the few burn places so I then clean them out with a diamond bit under water, or stone or sand.
You can't know how each object will fire, every time, since sometimes temp of kiln is not "soaked" or preheated enough. Also you could be taking too long on 1 loading to open door, place trivet, and close it. This lets temp drop too low. Lots of variables. Besides Edmund mentioned lots of things that stay the same at your studio, but changing conditions also play a part. Just keep having fun, practice on 'non precious' metals more at first, and enjoy the unexpected until you get more predictable results. Then adapt your method to nicer metals and fussier types of enameling. I still think my fascination with enamels is due to surprises, rather than completely controlling the process.
No, I think it not a try and error play!! If you into the kiln look, (eye-protecting glasses) you can see very well whether the enamel surface is smoth and glossy or not. You can also the workpiece do out of the kiln in order to criticize the state of the surface. If it is a bit wavy, do it, for a short time into the kiln again.
I have a very comfortable pyrometry in my kilns. But I burn only by sight, so as described bevore.
Edmund
I have two issues that I would like input on how to solve, please:
1. After etching copper I use clear flux to seal the copper and so I can add transparent enamels - however, it turns black and ruins my etching. I've tried burning it hotter and longer to no avail. I'm using a Japanese lead based enamel but I've also tried lead based from Thompson and still no luck.
2. I understand the rational for counter enameling a piece - but it seems a waste of silver. Do you grind the silver off the back after enameling? It seems customers would prefer to have a nice silver back rather than enameled. Thoughts?