I have been doing a lot of glaze testing over the last few months and I wanted to have a recap on what I have done, what works and what I need to do, so I thought I should get all my tests out that I have done so far. Below is a picture if them all laid out.
Below is my Number 10 set of glazes. The base glaze recipe is:-
Potash Feldspar – 50
Dolomite – 20
China Clay – 20
Bone Ash – 10
A previous blog post lists the oxides I added to each tile.
This glaze needs to be fire to a high temperature of above 1260 – 1280°C to get more of a glossy finish. Some of these glazes will work well with being spring colours.
The next set of glazes are stand alone glazes I found in some glaze recipe books. The top right tile I really like so I have done some other colours in it (see below, Number 9 glaze).
The blue tile next to the green tile I like as it is bright and light and I think it will work well in summer and spring colours. This glaze I will experiment more with blending them with other glazes.
I wanted a pink glaze for blossoms for spring colours but this glaze is too ‘shocking’.
As you can see I have tried a few white glaze recipes but so far I am not happy with them. I want a bright white glossy glaze which these are not so I’ll keep try different recipes .
This next set of glazes I thought of trying to do a colour blend test and to then see the difference with firing in oxidation and reduction. the base glaze is:-
Feldspar – 50
Whiting – 20
China Clay – 15
Flint – 15
The first set is coloured with black iron oxide and the second set is cobalt oxide these are the percentages I used on each tile – .25% – .50% – .75% – 1% – 1.25%
The test shows that black iron oxide needs to be a higher percentage to get a deeper colour while cobalt is very strong and only needs a very small amount.
The test on the left of each set has been fired in reduction with the other side being oxidation. The cobalt oxide doesn’t show much difference but the black iron oxide has made a vast difference.
The clay used on all is B17C
This next set is my glaze number 9 which I got from ‘Colour in Glazes’ Greg Daley pg 70. In the book is it has 1% of copper oxide added making it a sea green crystalline glaze. The tests I have done replaces the copper with the
soda feldspar – 42
Dolomite – 22
Whiting – 3
Zinc oxide – 5
china clay – 4
bentonite – 2
quartz – 22
This list is the added oxides:-
a – purple iron ox 1%
b – Copper carbonate 1%
c – manganese dioxide 1%
e – yellow ocre 1%
f – red iron oxide 2%
g – zinc ox 5%
h – black iron ox 5%
I – titanium ox 2%
j – cobalt carb 1%
k – nickel ox 2%
The top was fired in oxidation to 1260°C with the bottom in reduction to 1300°C. The clay is B17C.
Oxidation has fired well giving a nice glossy finish but I don’t this the glaze likes to go a higher temperature or being fired in reduction as it has come out all dull and milky looking. However the bottom left glaze would be great as a winter colour as it is very frosty looking so I will have to try that.
The percentages of oxides I have used is not strong enough, I need to up the percentage to around 5% to get stronger colours.
This next set of glazes in my Number 16
Nepheline syenite – 40
Flint – 30
Whiting – 20
china clay – 10
The following oxides have been added. As I mentioned before I need to up the percentage of oxide:-
a – iron oxide purple – 5%
b – chrome oxide 5%
c – manganese dioxide 5%
d – yellow ochre 5%
e – red iron oxide 5%
f – zinc oxide 5%
g – black iron oxide 5%
h – titanium oxide 5%
I – Cobalt oxide 2%
j – nickel oxide 5%
The above tests are not very interesting and I needed to add rutile so the tests below are the same but with 5% of rutile being added with them being fired in both reduction and oxidation. The results are a lot better.
This next set of glazes are the same base glaze of number 16 but with the following oxides being added. I wanted to concentrate on autumnal colours such as oranges, browns and greens.
With this set of glazes I will do some blend tests and then put onto some of my pots.
I have found doing this review very helpful as I found myself getting lost amongst the tiles and not knowing where to go. Having discussions with Dave has helped me to concentrate on a season at a time and not just keep doing a range of colours. That is what this last set of tests were for, autumn colours.
What I plan on doing next is to do a blended tile tests to see how the glazes react to each other. First I will concentrate on autumnal colours then I will try spring colours.