In part one I discussed the preparation of glaze tests. Here’s the results just in.
All of these had the same amount of yellow iron oxide added, to each of the 13 body mixes. As you can see I was not very committed to sieving and a large amount of speckle resulted.
A book of colours seems to bring me out in a major attack of ‘kid-in-a-sweetie-shop’ and for this first round of glaze testing I got completely swept up in all the lovely possibilities, resulting in a large number and wide range of tests. I ran out of tiles at one point so later mixes had to go onto experimental bisques.
The results of all this colour was two-fold. Firstly I realised that some of these glazes, which officially all needed a 1290 firing but were tested at 1260, actually worked fine at the lower temperature whilst others didnt. As I share a kiln there’s some incentive to stick with glazes that work at 1260 so that I can at least occasionally share firings with the others.
Secondly I realised that I had been blinded by temptation and hadnt really focussed on testing the types of colours I was most interested in. I’m not at all keen to work with blues – but tested several anyway. Nice – but a Waste of time!
I also found that one of my other glaze books did actually say whether or not things were food safe, as well as recylcing and commenting on recipies from a third book in my collection.
So, for round 2 I was much stricter about focussing on the types of colours I wanted to use, and testing promising sounding variants of these from the other two books. The results of these tests were sieved, and came out of the kiln this morning. Again some mixed results…
Quite a range from very shiny and almost transparent to very smooth matt that exaclty matches the colour of the clay, plus one wild crystalline one that is hardly white at all. I’m not totally wild about any of them, but the strongest contenders so far are these.
I like a bit of speckle, but those on the left look a bit like grit rather than a speck of colour, and the one on the right has a slightly green tinge plus bubbles forming in the centre (which I think may be something to do with the firing?). I dont seem to be able to make any immediate decisions at the moment so I’m living them for a bit to see if one becomes the favourite.
These include a range of different bodies plus between 8-12% red iron oxide. I like having a black that is slightly warm, not too flat, and not made out of nasty toxic substances, so these are an improvement on the very flat black from round 1. So far the contenders are:
I was hoping for a softish jade green, and also tantalised by Emmanuel Cooper’s recipe for a copper glaze using silicon carbide to create an internal reduction and produce blood red (“if obtained” as he puts it). As you can see, red was not obtained. A couple I think may have been put on too thinly and turned out transparent with specks, and one became a nasty volcanic type texture for some reason I have not identified yet – presumeably some errant silicon carbide?
However, I did come up with this, not quite anything I had previously imagined, and not something that sounded super promising from the description in the book, but something I really like! It has a clear jade body with copper and black crystals at different depths and changes significantly depending on the thickness from shiny clear to matt black to the full blown colours. Great variations, depth and visual texture I think, so this one is definately in the mix.
This gives me a couple of shortlisted combinations that I will need to live with, and perhaps test together so see how they work in combination, literally overlapping to see what the chemistry does, but also adjacent to judge how much speckle one pot can happily carry…