Saturday, September 26, 2009

Reworking a glaze for testing

So I have a version of strontium crystal magic I had some decent success with and want to line test it with yellow iron oxide to see if I can coax a good orange out of it.

First thing I want to do is normalize the recipe to 100 grams. This is done by getting the total weight of the ingredients ... I'll call that W then dividing each ingredient by W. I'll call each ingredient's weight x. The result of this equation is the normalize weight I am after, I'll call that number... R. The equation is pretty simple:

R = x/W

Keeping in mind that R will be a decimal, less than one. It can best be thought of as a percentage. I set up a simple spreadsheet template to handle this for me.

Here is my initial recipe:

Strontium Crystal Magic

Custer spar 120

Whiting 45

Strontium Carb (type D) 33

EPK 39

Fr 3124 12

Lithium Carb. 12

Titanium dioxide 36

Bentonite 6

Yellow Iron ox 6 for orange

Now I did one other thing to get this recipe ready for line testing. I pulled the yellow iron oxide out of the recipe. I did this because I want the main recipe, the recipe without colorants to equal 100. I can add colorants later. Here are the R values I get for this recipe:

Custer spar 40
Whiting 15
Strontium Carb 11
EPK 13
3124 4
LiCarb 4
TiO2 12
Bentonite 2

Add it up and you get 100. Which is much easier to work with when testing a glaze. Now because I pulled the yellow iron oxide out and it was initially 6 I know that it was initially about 2%. So I am going to start my line test at 3% and go to 13%.

For line tests I use 100 gram batches mixed up in the plastic beer cups you get when you go to a party. I'll mix up 10 identical batches of dry ingredients then drop in the correct amount of colorants, add water, drip or brush my tiles (spraying them is a hassle) and wait for the next firing to see the results.

No comments: