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.

2013-02-18 13.10.45

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.

2013-02-18 13.19.32 2013-02-18 13.37.06 2013-02-18 13.50.47


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…


whitesQuite 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.

white 1 white 2

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:

black 2 black 3 black 1


accent testsI 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.green crystal

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…short list a (2) short list b



11 thoughts on “Glazeology part 2: the results

  1. all very interesting glazes, i am myself studying glazes at the moment at uni, my exhibition is coming up soon and im testing my glazes on slipcast stag beetles, have you got any advice? and also whats the best glazing book you have come across? šŸ™‚

  2. Hi Chloe,

    Thanks for your comment. I’m not sure I’m really in a position yet to give advice – I am still learning the value of actually following the instructions in the books on things like sieving and temperatures, having learnt from experience that you dont generally get very good results if you dont. Ahem. It is fiddly and time consuming, but actually doing the tests is something I find helpful, and it sounds as if you’re well into that.

    At the moment I’m mainly working from Emmanuel Cooper’s “Potter’s book of glaze recipes” as it has the largest number and range of any I have, including for example about 40 whites. The range is very helpful when you’re searching for the elusive colour of your dreams, but not many are illustrated so you’ll have to test them, and he doesnt say which recipes are food safe or not. Linda Bloomfield’s “Colour in glazes” is a useful companion in that respect and has a smaller number of recipes but still a good range of colours, all illustrated.

    Good luck!

    • Thank you. The green is proving a bit of a pain, it settles immediately and is very heavy and the colours are elusive as the results are very variable depending on the thickness of application – from shiny white to matt black to full on crystalline green – but I love it when it works so cant resist.

  3. Jane – great to see your tests. I like that surprising green too – very subtle. I like your blacks too – they are hard to make because the oxides that make the black tend to over-flux the glaze, make it runny…

    I like the Ceramic Review Book of clays and glazes – it’s not the easiest one to use, but it has lots of different ‘styles’ of glaze. A lot of other books tend to be one particular kind of surface/ ‘mood’.

    • Thanks Carys. The black I use is actually very stiff – despite the massive amounts of iron oxide.
      I don’t have that book but it sounds useful, that variety of moods sounds great, will have to check it out!
      On another topic entirely, do you know of anyone who does kintsugi professionally?

      • No, sorry. There was a fantastic visit to the Ashmolean in Oxford by Japanese kintsugi artists – they are also laquer specialists, that’s the base technique – where there were some curators, people doing workshops, but I didn’t meet any UK practitioners. UK go more for invisible mending, I think, using resin glue not lacquer. All hugely expensive, sadly.

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