I was delighted to be asked to test a mineral pigment which is being mined locally, I love experimenting and seeing where these experiments will take me.
Something I found very poignant is that some of my china painting friends in the USA call themselves mineral painters, as our pigments are based on mineral oxides.
I had a few preconceived ideas of what would happen with the oxide but those ideas were turned on their heads as you will see.
So firstly I did a test fire on glass just to make sure the pigment didn’t fire out completely, the result surprised me as all of the colour remained. The next test fire was on a ceramic tile; iron based red china paints are quite notorious for firing out or changing colour, but fired to 780 centigrade the oxide colour held rather well. So I fired to 820 C, which is hotter than I’d fire my iron based china paints, again the colour held. 900C and still the colour has not fired out or turned black, it’s not very shiny even though I added flux but that’s ok.
Following the initial glass test I tried some oxide on Bullseye glass with other inclusions such as mica, frit and bubble powder to see how they would react. They almost all worked well but the penwork and sgraffito pieces haven’t worked so well.
I was thinking of ‘A walk in the woods’ as theme for my work so I decided to try fusing some leaves coloured with the oxide, this was one of the first glass fusing techniques that I learned way back in 2006 on a glass fusing course with Bill Swann. I’ve always loved the look as they remind me of fossils.
With the woodland theme going on I painted 3 glass panels and much to my surprise most of the colour fired out, so why did this happen when the colour held on the ceramic tile, and the pendants? My thoughts were there was a reaction between the oxide and the other inclusions, but that didn’t happen with my test fires, I think it had to be down to temperature. So I repainted the panels and fired again slightly cooler, this time I think I proved that the oxide is very temperature sensitive, the glass was placed on 3 batts in the kiln, the top one lost quite a bit of colour, the middle one not as much, and the bottom one had the most colour remaining.
Here are the pendant cabochons, I think they look great, I will be introducing them as a new jewellery line. I’ve used a silver bails for photography purposes but I think they will look nicer with a copper bail when the order arrives.
And here’s the porcelain vase ready for firing, I would have expected some colour loss, and also iron colours fired hot often go black and look rather like graphite, but now I’m not so sure. It’s a different clay body, and glaze to the ceramic tile so anything could happen. It’s in the kiln now and I will just have to wait and see what’s happened when I open up tomorrow. That’s what I love about experimental work.
I’ll post a picture of the fired piece tomorrow.