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Ian Currie Test Tiles Forums?


curt
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  • 2 weeks later...

Ah! I forgot to post them. The white glaze was nothing interesting to look. However, I refired an old grid I had made just to see how the second firing and the slower cool would do. It came out very interesting. I will have to set up my photo booth to capture the tiles properly. I will do it next time I take pictures.

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  • 1 year later...
  • 1 year later...

Just found this thread! I'm having a hard time figuring out how to calculate a recipe from a volumetric test from a triaxal/line blend. Ian Currie's website/calculator doesn't work for me, which I think did this calculation automatically: ian.currie.to Is it working for anyone else?

Question: If I have two glazes, and its a 10/90 blend, Do I take 10% of all the dry ingredients from Glaze 1 and add it to 90% of all the ingredients from Glaze 2? I started doubting that this was the correct way to do it when my "new glaze" didn't equal 100.

Thank you!  

 

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A volumetric line blend is made from glaze batches of equal recipe amounts and wet volume. Make 500 gram batches each of glazes A and B, add appropriate amounts of water and sieve them as usual. Measure the wet volume of each batch and top off the one with less volume with some water until both are exactly the same volume of wet glaze. Remix the one that you added water to just to ensure it is uniform. You will need nine test cups plus the two original batches, and a 100ml syringe.

In the first cup, put 10ml of glaze A and 90ml of glaze B. In the second cup, put 20ml of glaze A and 80ml of glaze B. In the third cup, put 30ml of glaze A and 70ml of glaze B. And so on through the nine cups, with 90ml of glaze A and 10ml of glaze B in that last cup. There should be enough wet glaze left in the original 500g batches to serve as the 100% endpoints of the line blend. Thoroughly stir the mixtures in each of the 9 cups.

The dry recipe of any of the blends is basic math. To start, the base for both recipes must initially total 100 (or a consistent amount). If the base for recipe A totals 100, then 10% of all the individual materials in it will total 10. Similarly for recipe B; 90% of all the individual materials in it will total 90. Add them together and the new recipe will total 100 again. Making a larger batch is simply a matter of multiplying everything in the new recipe by the same number, as with any recipe.

Edited by Dick White
added the math part.
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As long as Glaze 1 and 2 are mixed to the same volume then it is pretty easy. 

You know the weight of dry material added to each glaze and the volume so just divide dry material by volume to get grams per milliliter. Now if you add 1ml you know how much dry  material has been added to the glaze.

 

I suppose you don't even need each glaze to be the same dry weight or volume but it makes it easier.

Edited by High Bridge Pottery
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Volumetric  blends are easier to understand when you’re only isolating one ingredient in a base glaze, or if you’re doing something like colour blending. And it makes the math a lot easier to use 100g  batches , because then you don’t have to convert odd numbered weights into percentages, and there’s less rounding that adds inaccuracy. You can mix larger volumes if needed for the physical testing, but on paper, do your math as percentages.

As an example, if you’re trying to find an interesting colour mix of 2 stains in the same base glaze, and the starting samples each have 3% of one stain (A and B), then a 90A:10B mix would contain 0.9(A) and 0.1(B). Which would be 2.7% stain A (or g, in a 100g sample) and 0.3% of stain B. You don’t have to mess with adding the base recipe ingredients, because they’re the same.

If you’re mixing 2 different base glazes, it’s the same principal, but with more ingredients. 

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Thank you all for the reply! It was two different glazes I was mixing. Sounds like my math was right, so time will tell when I pull the tests out of the kiln tomorrow morning. 

Much appreciated, thanks again Callie, High Bridge and Dick!

Update: the "ReTotal" calculator in Insight-Live is so much better to do the calculations and minimizes human error (which I definitely think I did the first time with pen and paper!)

Edited by packrat31
Update: ReTotal in Insight
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11 hours ago, packrat31 said:

Thank you all for the reply! It was two different glazes I was mixing. Sounds like my math was right, so time will tell when I pull the tests out of the kiln tomorrow morning. 

To calculate the solids formula for a glaze made by volumetric mixing two glazes you need to know the weight/volume for each of the constituent glazes.

Pedantically you only need their ratio, so most volumetric blenders make their constituent glazes to the same weight/volume to simplify the maths.

However you can estimate the weight/volume of a glaze using Brongniart’s Formula.
http://www.potteryatoldtoolijooaschool.com/brongniarts_formula_made_easy.pdf

... might be interesting to try for the mix you made.

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