Dealing with wollastonite lumps

[Min]

In @Magnolia Mud Research 's post he found 10 - 12% the sweet spot. Perhaps what is needed for concrete retardant isn't the same requirements for changing the crystal structure for the agglomeration issue of wollastonite. Interesting for sure, it would also be interesting to test different slaking times. Perhaps less sugar could be used if slaking period was longer.

[Magnolia Mud Research]

1 hour ago, Min said:

In @Magnolia Mud Research 's post he found 10 - 12% the sweet spot. Perhaps what is needed for concrete retardant isn't the same requirements for changing the crystal structure for the agglomeration issue of wollastonite. Interesting for sure, it would also be interesting to test different slaking times. Perhaps less sugar could be used if slaking period was longer.

1.  The 10-12% sugar was added to the 100% of the other ingredients and is not a ratio of sugar to cement;  put another way, to 100 grams of the glaze components I added 10-12 grams of sugar.  Since it worked, and was a "let's see if this will make an interesting glaze"  project and the slurry remained OK, there was no incentive to optimize.  I was interested in the fired glaze, not the recipe.  The glaze was a beautiful clear over a low iron stoneware; with a pinch of cobalt it make a nice blue. 

2.  My mixing process was to estimate the amount of water needed based on the true volume of the solids and use a volume ratio of water to solid volume starting point around 0.6.  the solid ingredients are added to the water with vigorous mixing in this order: solubles, mix, clays next, mix, light rocks, mix, and heavy rocks last, mix; add a little more water (with vigorous mixing) if the slurry is too thick, and a final vigorous mix. The glaze is ready to use.  for the cement glaze, the sugar was added to the water first.  
Yes, this is NOT what the standard studio textbook teaches ; it is how I was taught to put solids into a slurry (but then, ik ben een chemisch ingenieur). 

3.  A long range problem with Portland cement as a calcium source for glaze is the storage time of a bag of Portland cement is short, on the order of a few months; once the bag is opened, moisture migrates into the bag and the bag becomes a big lump.   

LT

[Piedmont Pottery]

On 9/5/2021 at 3:56 PM, Callie Beller Diesel said:

I can see it not being a big issue if the sample is left undisturbed, and there’s limited opportunity for other bacteria to be introduced. Sugar is a preservative, after all. But even soda will grow mould if left open and bacteria is introduced. 

If you accidentally dump your old sponge into your glaze bucket instead of the rinse water next to it on glaze day, I could see some interesting new things growing in there a few weeks later.

First, thanks for jumping into this question with so much energy.  You and everyone else on this forum are fantastic.  I am wondering if sucralose might work similarly to sucrose.  Sucralose inhibits bacterial growth, so might be a good alternative to sucrose if it works similarly.  I will try it next time I make up one of these glazes.

[PeterH]

1 hour ago, Piedmont Pottery said:

First, thanks for jumping into this question with so much energy.  You and everyone else on this forum are fantastic.  I am wondering if sucralose might work similarly to sucrose.  Sucralose inhibits bacterial growth, so might be a good alternative to sucrose if it works similarly.  I will try it next time I make up one of these glazes.

From glancing at a few cement papers sucrose/table-sugar works better than most [all?] the common sugars, presumably because its shape and charge distribution help it make good "contact" with the surfaces it effects.

On the other hand sucralose doesn't seem a major change in shape (no idea about change in charge distributions).

Probably worth repeating Callie's 2.5g test with  sucrose and sucralose?

PS The bond for the Cl on the left seems to have changed from into the plane of the paper to out of the plane.

https://www.thoughtco.com/wedge-and-dash-projection-definition-602137
A wedge and dash projection is a drawing, a means of representing a molecule in which three types of lines are used in order to represent the three-dimensional structure:
1. Solid lines to represent bonds that are in the plane of the paper
2. Dashed lines to represent bonds that extend away from the viewer
3. Wedge-shaped lines to represent bonds oriented facing the viewer

PPS Looking up the Molar Masses in wiki suggests that molecule-for-molecule substitution requires 1.16 the weight of Sucralose.  Looks like ~27% of the weight of Sucralose is chlorine.

[Hulk]

Very interesting, echoing Piedmont's thanks.

There's enough Wollastonite in my glazes, seemed to make sense to buy a fifty pound sack. I'm running glaze through an eighty mesh if it's been more that a few weeks since using/mixing it up, finding a few bits of random stuff, sometimes, and  up to half teaspoon of little agglomerates (thanks for that word). Several glazes also use Gerstley B, so there's that as well.

The sugaring, that's interesting.

[Callie Beller Diesel]

Further observations. When I went to dispose of the test sludge a couple of days later (I screened them all into one cup), It all flowed out into the glaze disposal bucket quite easily. So perhaps the effect becomes more pronounced with more time for the material to hydrate.

[Piedmont Pottery]

A quick nonquantitative trial of sucralose vs. wollastonite.  I had two 1kg test batches of glaze with the same base glaze formula, different colorants in each, but the same amount of wollastonite.  Each was added to approximately 120 ml water, 2 g of sucralose was added to one, and each was allowed to slake for about 2 hours with frequent mixing, then filtered through a small sieve.  The image on the left below (or top, depending on your browser) is the residue from the one with sucralose, while the one on the right (or bottom) is without sucralose.  Visually,  although difficult to tell from the photos, the glaze with sucralose appeared to have about half as much wollastonite agglomerates on the filter as the one without.  In each case, the aggregates could be dispersed through the sieve with gentle pressure from a silicone spatula, but the sucralose sample dispersed more readily.  Based on this quick and dirty trial, it seems like it will be worth while to repeat this a bit more rigorously.  I have to admit I was surprised by the apparent effect of sucralose, as I wasn't expecting to see much difference with this test.