The glycerin is more of a humectant which attracts moisture.

For chemicals I use Amazon or Ebay.Much cheaper and in better containers than a ceramics supply place likeLaguna.

https://smile.amazon.com/gp/product/B006TTQTH4/ref=oh_aui_search_de...

Buy Propylene Glycol not Ethylene Glycol which is a poison if eaten.

Even stuff like Sodium Silicate. I like the containers with handles. https://www.ebay.com/itm/Sodium-Silicate-37-5-Type-N-1-Quart-Water-...

Or Calcium Chloride https://smile.amazon.com/gp/product/B005Y34T3W/ref=oh_aui_search_de...

How much propylene glycol to be added to dry glaze mix any reference points thank you

Norm Stuart said:

Gum burns out while Bentonite and Clay do not.

So the one glaze I add gum to is a "red cadmium frit "which is degraded to dark red or black with the addition of any bentonite or kaolin.

So I need the gum to suspend the frit and harden the glaze or frit and keep it attached to the bisque when it dries. Bentonite or 10% kaolin or clay in most glaze recipes can do this as well and better than gums.

Most gums are long strands of carbohydrates which attach to water and create a jelly-like suspension. They are a mild deflocculant (causing glazes to settle) and their addition makes the glaze take longer to dry. Guar gum is used in puddings and gravy (or glaze).  Guar gum and sand is used in fracturing oil wells because the addition of a little acid makes the guar gum suspension go as runny as water, locking the sand in place in the cracks as the watery guar gum drains away.

Gums without a preservative quickly turn black with mold. By adding 1% Sodium Bezoate and 0.5% dry Citric Acid the gum will not mold, and the citric acid is a flocculant which will counteract the deflocculating properties of the gum. All prepared liquid gums all have some type of preservative.

I add these preservatives to hot water and 10% by weight of dry gum arabic to make glass glue, to hold glass pieces together prior to doing a "Bullseye warm glass" firing.

I sometimes add to a ceramic glaze a "brushing media" like propylene glycol to help smooth out the brush strokes. In my experience Gums make a fairly lousy brushing media as you've noted.

Propylene glycol or glycerine do evaporate, but more slowly than water. Someone once suggested Floetrol paint additive as a brushing media, but I found it less useful than propylene glycol and more costly.

So I mix red iron oxide with propylene glycol to make "ink" to mark test tiles. If I add water, the ink pot is dried up by the following day. The propylene glycol takes a month to evaporate to dry red iron oxide, But it "dries" sufficiently on the test tile as soon as I write with it.

Add a brushing media like propylene glycol (a liquid) to glaze after you've already added water and sieved the glaze.

Just one percent or so improves the flow in chalky glazes when applying. Propylene glycol does evaporate, but slower than water.