Line blends are a great way to see an incremental progression of changes from the addition of a material. 

The “progression” line blend is more common because it isolates the change in each tile, making it easier to see that change. The method tests one material against a base recipe. For example, in the Progression method, one might test a colorant on an existing recipe, or perhaps an opacifier on a clear glaze, or a flux on a glaze that normally doesn’t run, or .. who knows, the possibilities are endless!

Progression:

Directions:

1) Mix 300 grams of the base recipe you will be testing. Mix with water to a whole milk consistency and sieve

2) Dip a tile into the base recipe and label it #1. If your tiles are large enough, dip once nearly to the bottom, wait for it to dry, then dip the top half again so that you can see a thin/thick comparison

3) Add 3 grams (1% of 300) to the cup and mix well with a hand blender. Dip a tile and label as #2. Keep in mind that for some materials (like cobalt) 1% might be too much. For those materials, you should line blend in .5% increments (1.5 grams if you’re using a 300 gram base).

4) Add 3 more grams to the cup (now you have 2% of 300). Mix well, dip a tile, and label

5) Repeat until you get to the end. You might have to add a little water as you go so as to maintain the same consistency (whole milk consistency).

6) This method will approximate the percentages, but it is a good (and efficient) method for line blending. While this method is fast, it does shift the percentages a little as you go up the blend. But, it’s a good place to start and you can get more specific late if you see something you like in the tests. 

Here’s a demonstration of John Britt doing a progression line blend, although he estimates his weights rather than weighing out each material. In this class, we will weigh out each material – unless the amounts are lower than the scale’s accuracy. If that’s the case, then use the system John uses in his video.

Another type of line blend is known as the “standard” line blend. In a standard blend, you test two materials in combination with each other in amounts that diminish in reverse correlation to the other material’s increasing amount.

Standard:

1) Make a line of party cups, marking each with the test # in the table above

2) Weigh out 100g of material A and put it in cup #1. Then, weigh out 90g and put in cup #2, then 80g in cup #3, and so on until you get to the last cup, which will not have any material A in it. 

3) For material B, you do the same, but in reverse – nothing in cup #1, 10g in cup #2, 20g in cup #3, 30g in cup #4, and so on until you get to cup #11, which should have 100g of material B and no material B. 

4) Then, mix water into cup #1 until you get a “whole milk” consistency and dip your tile. Repeat for each of the cups, making sure that each tile is mixed to the consistency of whole milk