Torch fired enamel problems

Morning all. Im new to enamelling. Getting reasonable results. I counter enamel on the back and it looks good, but when I flip it over to torch the front enough to melt the enamel, it ruins the back with hazy shadows and rough areas on what was at first smooth
My first thought is that Im getting the second firing too hot but Im trying to only apply enough heat to melt the enamel, but there is what looks like a flame shaped mark where it has lost its shine
I then tried a little home made mini kiln made from firebricks and that was a better result, although took more time
Do I need to back off with the flame and take more time?
Ive seen videos where the person just goes ahead and torches it directly, seemingly without issues.
Im using Vitrum Signum opaque
Regards
Jack

Hi Jack,
I am no expert here, but is seems you are probably burning the counter as you self diagnose. Enamelling is a process that requires patience and much trial and error. Take your time to work out what works for you.
Have fun doing it.

It would seem so. Im going to try putting a firebrick enclosure over the top and heat from below to try and recreate a kiln environment

Hi Jack,

I'm a learner myself. Probably overheating the enamel. A kiln will give a more general heat whereas a torch is more focused.

Vitrum Signum is a retailer I think so the brand of enamel makes a difference. I've found that some of the enamels are more sensitive to overheating than others. The other factor is that enamels of the same brand sometimes have differing melt temperatures, therefore, if you use a lower melting enamel first on the counter and then you use a higher firing enamel on the "good" side you are probably going to overheat the counter enamel.

I've used the Schauer range from Vitrum Signum:

https://www.milton-bridge.co.uk/imag...hart-sheet.pdf

The above colour chart also shows the melting temperature of the enamel, page 3 for the opaque and the last page for the transparents. You can see from this that what they call soft enamel melts at 700 - 730C and hard from 770 - 820C. I have used used enamels from the medium enamels and even within the range there is a difference, the rose enamels melt at the higher end of the range and the yellow green from the lower end of the range and I have overheated the yellow green by being overzealous with the heat. I haven't used counter enamel for this reason ( I have only torch fired the enamel). I do find that there is some distortion because of this and enamel can crack and ping off particular shapes, sometimes weeks after the piece has been enamelled! I've found that this is hasn't happened on the champleve enamel but has on one of the cloisonne pieces, it tends to happen just near the edge, I think perhaps more tension is setup if there isn't a metal edge to the piece.

Quote:

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Originally Posted by sofaboy

It would seem so. Im going to try putting a firebrick enclosure over the top and heat from below to try and recreate a kiln environment

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Let us know if this helps, it will be useful for others in the future as we build upon the wealth of knowledge already here.

Hi Alistair, Sorry, I thought I had responded to this. I spoke to Milton Bridge and they are sending me a sample of a high fire counter enamel, which would seem to be the answer. They also suggested 'undercooking' the counter and applying just enough heat to stick the enamel in place, thus alloing for more heat when firing the front

the problem with this is its hard to get a good look at the process when inside but it does help

Quote:

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Originally Posted by sofaboy

Hi Alistair, Sorry, I thought I had responded to this. I spoke to Milton Bridge and they are sending me a sample of a high fire counter enamel, which would seem to be the answer. They also suggested 'undercooking' the counter and applying just enough heat to stick the enamel in place, thus alloing for more heat when firing the front

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Sounds like a plan :-)