If you have ever tried to make just the right shade of pink glaze, you know how tricky it can be.
In the past couple of months, I have been testing out a variety of recipes and variations and while I eventually got close to my goal, I wanted to run a little study on the mix of tin and chrome in glazes.
My goal with the initial recipe was to create a pink variation of my icy blue glaze: a soft, pastel, transparent-looking pink that I can use on delicate porcelain pieces with embossed details. To make this kind of pink you really don't need a lot of chrome, so my study focuses on very small chrome quantities, which is something I find very valuable. To reproduce this work you will need a high precision scale that can measure down to at least 0,01g.
The test is designed as a biaxial blend: I mixed 1000g of dry ingredients, added 1000g of water and then divided up the batch in 9 separate 200g glaze batches in smaller buckets. I only ended up using 7 for this test but you can continue if you so wish.
Each of the 7 buckets got an increasing amount of tin. The first has 0,5%, the second 2% and so on.
Then I treated each small bucket as the starting point for a line blend test. I added increasing amount of chrome: I started with 0,01%, dipped a test tile, added 0,04%, dipped a test tile and so on. I designed the increments to be small.
All tests were fired at cone 6 (1240C). Clay body is Limoges Porcelain.
Click on the image below to download/see a bigger photo.
With the right base chemistry, there is a point where, between 3% and 5% tin, the chrome additions will result in a pink glaze (as opposed to green). After that, increasing chrome will make the glaze increasingly more purple.
When it comes to the base chemistry, the base glaze needs to contain high levels of calcium, which in this case are given by the wollastonite.
The base recipe is a pre-existing Blush Pink glaze found on Glazy. I chose it because it had a good amount of calcium.