Hi Trish

Thanks for the reply.

Well I have been through a learning curve regards cleaning the copper but I would say my current cleaning regime is pretty good, I also do various forms of metal plating and the cleaning demands there are pretty demanding, also the other colours do not demonstrate the same difficulties.

Since you get a good result with thompson then it looks to me as if the chieft suspects are either the enamel or my use of a torch. Although we may not be comparing strict like for like as I do grind the gloss away and the bubbing is beneath that but black is generally more difficult for me whether I grind or not.

I will get hold of some thompson and try that.

Thanks for the reply

My guess is that your coat of black is too thick and you may be overfiring it. I use 2 coats of black as opposed to 3 coats for other colors. I use Thompson's 1995 black and it covers well and becomes smooth and glossy easily. Can you tell I love it? If you want a matt coat, you might try glass etching cream instead of grinding.

Hi Chris,

Thanks for the reply, at the moment I am working only on test squares so they are fired horizontally with no binder. Later on I will have to explore methods of binding but for now its not part of my problem but I do understand that binders have been known to give people problems. Thanks Jon.

Hi Candy

I have experimented with different layer thicknesses although I am still considering overfiring as a potential culprit, I have wondered if the torch flames create an uneven heat as they move around the edge of the square.

Thanks for the Thompson recommendation, I am tempted simply to try blacks from different manufacturers and see how that goes.

Jon, have you looked at Chris Hierholzer's tutorials in the Torch Firing group? He starts firing quite far below the piece and gradually moves closer. The supports for the screen are marked in inches so you can see just how far below. It's a fairly slow process and you may be rushing it. But Chris can tell you about all that.

Hi Candy

Thanks for that - I am new to this site, I had not seen the group tutorials, Chris's tutorials look useful to me. I am not applying wet but I can see that whilst I do start from quite a distance I go in a lot faster than I think Chris does - I still have a hang up about getting too much oxidation on the metal ie a long period whilst the metal is hot yet the enamel has not started to fuse so I think I need to suspend that doubt and try going for a much slower approach - I will give it a go - thanks for the tip.

You're welcome, Jon. Others may have a better theory but I believe the glowing copper burns off the oxidation and allows the enamel to fuse. You are getting the whole piece red hot before the enamel starts to fuse so it doesn't cause a problem. I enamel copper beads on a stainless mandrel and never clean them. As long as the bead is glowing red when I dip it in the enamel powder, the enamel sticks and fuses just fine. Here's a photo of small copper beads torch fired on a mandrel and dipped in enamel powder. The ridged beads are iron, also uncleaned.

Hi

I am a newbie - I have been intensively experimenting and researching enamels in conjunction with the artisan business I will be starting later this year. ( I would prefer not to say what I will be manufacturing at this stage - I hope no-one minds me being cagey on that one ).

At the moment my research consists of working with 1.5" squares and a blow torch, I will be building my own specially designed kiln but in the meantime I am testing small scale.

I have found black opaque (on copper) to be more problematic than other colours and that is after using two different types of enamel both from the UK and both lead free ( Ball and also Milton Bridge ).

Problems include

1. Easy to over fire.

2. Gas/Bubbles - I always grind to a matte finish I never leave gloss, the bubbles are not in the top gloss coat but lie underneath and get exposed when I grind.

3. Sometimes little cavities that extend all the way down to the copper surface.

Has anyone else experienced issues with black? It does stand out for me in a class of its own regards "bad behaviour" ( or is it me ? ).

Can anyone recommend particularly easy non-leaded black enamels or perhaps another difficult colour that showed similar issues? I have read that black is one of the more difficult colours for the manufacturer.

For those who torch and kiln fire how do you rate the ease of using a good performing kiln vs a torch? For all I know the problems will go away as soon as I start using the kiln.

I always heat from underneath I do not play the flame on the enamel surface. I keep an eye on the enamel and stop as soon as I see full fusion, I do not even wait for a nice smooth surface as I do with other colours.

I have tried under firing and over firing. I am using electrolytic grade copper but I have used regular as well - I do not believe the issue is firing time or grade of copper but it could be that the torch is cruder than a kiln and in particular the underneath heating with glass which might lead to a disadvantageous temperature profile through the thickness of the copper.

Kind regards

Jon