Soda Ash Question (again)

[Roberta12]

I mixed a small batch of a matte glaze I had used at a workshop this summer.  The recipe called for a small amount of soda Ash.  I couldn't get it to go through the sieve very well.  Thinking if it sat for awhile, the soda ash might dissolve (magical thinking) and it did not.  I remember for a wash, a person needs to dissolve it in hot water.  How do I do that for a mixed glaze with specific amounts?  I used it on 4 testers to see what would happen.  It crazed on the porcelain, not on the 3 stoneware clay bodies.  Here is the recipe for Ayumi Aqua

NC4 Feldspar (minspar 200)   34.74

Strontium                                          19.09

EPK                                                          13.57

Dolomite                                            10.50

Silica                                                          5.27

Whiting                                                   5.25

Gerstley                                                 4.55

Calcined kaolin                                  3.6

Soda Ash                                               3.43

Copper Carb                                       1.0

Roberta

[Min]

I'ld run it through the finest sieve you have then let the undissolved residue of soda ash dry in the sieve then dump it out and pour very hot water over the residue and add it back to the glaze slurry. (If you try and scrape the undissolved residue out while it's still wet it's harder to get all of it out)

[Roberta12]

Thanks @Min

[Dick White]

You know you are going to have some amount of water in the slurry. I start mixing my dipping glazes at a rate of 1 liter of water per 1 kg of dry recipe. That typically will yield a specific gravity of around 1.5, which will be adjusted as needed after mixing and sieving. For recipes with soda ash, I  will boil half of the water in a small electric teapot, and dissolve the soda ash with that in a small bowl. It will take a few minutes of stirring and waiting until it is all dissolved, and then put that in the bucket with the rest of the water before adding the dry materials.

[Morgan]

I have a few glazes with soda ash in it and never used hot water just sieved like normal mixed in room temp water. Thread has me thinking my glazes are missing out haha…then again if it didn’t dissolve it probably wouldn’t have gone through 120 mesh? 

[neilestrick]

Not sure why they have calcined kaolin in the recipe. The EPK isn't high enough that you should need to calcine any of it, and the version on Glazy doesn't have any of it calcined. Seems like an overly nitpicky recipe, lots of ingredients in small amounts. Often these can be simplified with little change to the fired appearance. I'd try it with using all dolomite instead of whiting, or increasing the whiting instead of Gerstley. It's a cone 10 glaze, right?