Create a Synthetic Feldspar in Insight-Live

A step-by-step of how to duplicate the chemistry of Minspar by mixing other materials. You will learn the calculate process, the type of testing to do and how to keep track of the results with notes, pictures and links.

A. Insight-live

You can also watch this at Screencast-o-matic.com

First, let's see how to do the chemistry part.
In my Insight-Live account, I have made a recipe with only Minspar, I'll open it.
Let's look at the chemistry of Minspar (click on it), it has 6.5-to-4 of sodium vs. potassium.
In the Materials Manager I with search "nepheline|custer" (to show both).
Clicking on each to show their chemistry makes it evident that Custer feldspar has the reverse sodium/potassium (K:Na) ratio of Minspar and Nepheline has a little more Na₂O but a lot less SiO₂.
So it seems a blend of Custer and Nepheline could work, the latter diluting the amount of K₂O in Custer down to what Minspar has. However in doing that I will under-shoot the Na₂O, I will need an auxiliary concentrated source of Na₂O.
I create a new recipe with three lines, Nepheline (50 parts), Custer (50 parts) and Ferro Frit 3110 (zero parts). I will name the recipe and give it a code number (that code number links fired tests with their Insight-live records). Click "Done Editing", turn on the formula calculation for this recipe and assess.
This initial guess-recipe produces too much K₂O and not enough Na₂O.
Turn on Calculation Mode with an increment of 5.
Reduce Custer and increase Nepheline and try to match the K₂O and Na₂O. It becomes evident that extra Na₂O is needed: Add 5 of the frit. Then 10.
As we zero-in it becomes evident a little CaO is needed: Add 1 Calcium Carbonate. Then 1.5%.
At 60 Nepheline, 16 Custer, 6 Frit 3110 and 1.5 whiting we have all the fluxes matched.
The Al₂O₃ and SiO₂ need to be increased so add kaolin and silica to the recipe.
Nudge up the kaolin until Al₂O₃ matches, the silica until SiO₂ matches.
Retotal the recipe to 100.
This is only a small part of the work, now I must start testing.
Notice the work I have done: I entered notes; did a melt flow comparison test comparing how Minspar and this substitute melt at cone 6, I uploaded that picture and annotated it.
Next I tested it in a recipe called "Perfect Clear" - I'll search that and open it to the right. We mixed that recipe using Minspar and the substitute, glazed test tiles and did another side-by-side flow test - carefully documenting the results of all tests with notes and pictures. This gives us an audit trail of all the testing that was done here.
Let's link this L4441B to the Perfect Clear recipe.
It is also possible to find these recipes in our account by searching recent pictures and clicking on one - it shows what recipes it is linked to.
We have a group account at Insight-live, it has 11,000 recipes that Joe Schmidt I have done tests on in the last 40 years! Everything we have done is recorded with notes, pictures, data and calculations.

Links

Media	Substitute Ferro Frit 3134 For Another Frit I use my Insight-live account to do the glaze chemistry to replace Ferro frit 3134 with combinations of three other common Ferro frits. We will see the challenges of doing this in three different types of recipes.

Calculating a substitute for Minspar

Melt flow tests comparing the two felspars

Why do this? We did not have it in stock and customers needed to mix recipes. When the chemistries of the two feldspars are very similar substitution is often not a problem, especially when a recipe only calls for 5 or 10%. However, when a recipe calls for a significant percentage the situation becomes much trickier (in our cone 6 test recipe, "Perfect Clear", 40% Minspar is needed). Feldspars are almost a glaze in themselves, just needing silica and alumina to shift their chemistry toward 'glazedom'. In this project I calculated a mix of materials, in my Insight-live.com account, that sources the same chemistry as Minspar. I made cone 6 GLFL tests comparing the pure Minspar and Minspar substitute (left) and comparing the Perfect Clear glaze with each feldspar (right). As you can see, the similarity in melt flow is stunning! This is a good demonstration of just how practical and valuable glaze chemistry calculation can be.

Click here for case-studies of Insight-Live fixing problems

You will see examples of replacing unavailable materials (especially frits), fixing various issues (e.g. running, crazing, settling), making them melt more, adjusting matteness, etc. Insight-Live has an extensive help system (the round blue icon on the left) that also deals with fixing real-world problems and understanding glazes and clay bodies.

By Tony Hansen
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