Dear Mer,

Thank you for your input. (And I've also appreciated the other comments and tutorials you've given! God bless you, these are valuable.) Standing back, and thinking of all the suggestions I can see several areas that I have ignored, or not known about. The sharp corners is a good point, too.

I make plates= copper, flux fired, then silver foil fire, then flux, and line up all my colors in the same family, dark to light. One dot each, then it goes in the kiln for a give time that I know for the size that is appropriate. 1 x 3 = say a minute and 30 seconds. Not over fired. With these dots some are smooth and some are grainy, the grainy means it is a harder fire. These go on the bottom. And you do not put ones that show smooth next to the ones that are grainy in a enamel piece, either as this will also crack. The molecules do not mingle and become one.

This has been the best way for me to teach as you can see it. Thompson's Workbook tell you which is which but if you do not use all Thompsons you will not know.

Hope this helps! Happy Enameling,
Patsy
enamelinghotline.com

Dear Patsy,

Well, this is fascinating. I just completed making color samples of all I have (99 of them) and I noticed that some were exactly as you describe -- grainy. I didn't know what it meant ...until now. Fantastic, I'm thrilled with this information!

Hello Patsy,

This is interesting. I never learnt about coefficients of expansion until I started having contact with enamellers from the other side of the pond. The term we use to know which enamels to use in which order or next to which, is hardness. The tests you just described, we call them hardness palettes. It is also not advised to mix brands, at least without testing first

All this time, I thought that both these things were not the same, and that you had to have both things in mind, but that I mainly didn't have to worry because I tend to use only Soyer, and when I mix brands is when I have to be careful.

I have only ever had problems by layering Soyer and Schauer colours (if I remember well, it was Schauer on top of Soyer). Most of the times I do layer them, I don't have a problem (I use Soyers on top of Schauer 64 very often).
And I am now thoroughly confused, since those that cracked had very similar "hardnesses".

I think I really have to read the Thompson workbook.

What exact enamels are you using? I have had similar trouble using Schauer enamels in cloisons adjacent to Thompson enamels. The exact colors and their relative proximities can cause cracks. Also, there may be enough variation in firing temperatures of different colors to cause uneven cooling and cracks may take a few days to show up.

Tina Chisena

Dear Tina,
Thank you for your insights! I, too, have put Thompson enamels in cloisons next to Japanese enamels and I think this is certainly one of my problems. (And even worse if you put one on top of the other...ack!) In the last week or so I've been going over my cracked pieces one by one, trying to determine what has been the problem in each case. It has prompted me to start keeping notes through the enameling process, which I probably should have been doing from the beginning!