Red and pink glass are expensive, as gold is one of the ingredients to get these colours. I was recently asked to produce some glass for mosaic that matched a company logo - a bright deep but slightly whitened colour. As a ten centimetre square of pink glass costs nearly £10 I have limited my tests in the past, so I needed to research colours of the glass available and the colours available by layering different coloured sheets of glass. I decided not to start by mixing very precise powder samples, as I would need to be able to replicate any suitable colour easily.
Bullseye handmade art glass can be categorised in several different ways:
Transparent and opal
The chemical family they belong to - mixing these can lead to a brown blotchy glass no matter how beautiful the original glass sheet is. The main families are lead, copper, sulphur/selenium and the non-reactives.
Striker and non- striker. Some glass is stable in the heat of the kiln. It can be manufactured to look like the expected colour when you buy it, and you can use it in the kiln for several firings and the colour stays steady. A lot of items need several different processes in the kiln, and it makes the process easier if you can be sure that after a week of work you are going open the kiln and find the piece is still the colour you started with.
Striker glass has colour that is more fugitive. If you buy sheet glass the colour you want and then use it in an item, firing it several times to make the composition and shape you are aiming for, it is upsetting when the end product turns out blotchy and mis-coloured. To give artists more working time with the specified colour, less heat work is given to the glass in the factory, so that it will be stable for longer in the studio. This means that the glass does not look like its named colour when you buy it. The colour matures with the correct firing schedule. The pinks I have been using for these test require an extra two hours at 663degrees centigrade to develop their colour.
A result of this colour change is that every tiny scrap of these glasses needs to be labelled to make sure the kiln opening isn’t a surprise. I helped a friend make a winter snow scene with a beautiful blue sky, only to discover that it was a maroon sky when we opened the kiln a day later.
testing red, pink, coral and lavender mixes, and a few blues. Only 11 is lavender - the other similar glass is light pink.
glass test notes
It takes a full twenty four hours in my kin to run a normal firing cycle, so it’s a good idea to try to do al the variations at the same time. This is my third batch of tests - the first I ran with some crushed glass I had in very small amounts already in my studio, and then I made tiny samples to begin to understand the different glasses.
I’ll make a full table with the details for each piece and add in information from my previous tests. I do want to try more variations with different thicknesses and some alternative base glass but if could be a few weeks before that is done so I’m posting this first stage here. I’m particularly tempted by some orange overlaid with neo lavender tint that I saw in another artists work a few days ago.