Veegum T

[Dave K]

I am new to pottery and this is my first post. I did do a search but couldn't find any answer that applied to the problem I am having which is crawl and adding veegum t. The glaze is Potters Choice PC34 Light Sepia in a 5 gallon container for dipping. . Amaco suggested adding 4% veegum t but I see most manufactures say 1/2 or 3/4 of 1%. Any thoughts what is best and also how to mix it ?

 

Thanks,Dave

[neilestrick]

The glaze is crawling in the firing, or cracking in the application?

 

I would expect 4% VGT to gel up and thicken your glaze a bit. I can see how it might help with application, but not necessarily with crawling.

[Dave K]

Hi Neil ,thanks for the reply. The crawling happens during the glaze firing. I have been using Standard clay 182 and 240 and firing at cone 6. I am very careful the clean the bisque pieces and wear latex gloves when cleaning and glazing. I have read that glaze application can cause crawl. I have only used dipping glaze twice. Could the problem be that the glaze is too thick? The mixing directions are a little vague for a beginner.

 

Dave

[curt]

It does not make sense to me to add a clay-like (smectite) material to something that is already crawling.  In fact, it seems like it would make the problem worse because clay is a high-alumina source.  Alumina is the single ingredient in ceramics with the highest surface tension and highest melt viscosity.  In fact, if you want to reduce crawling, replacing or eliminating alumina-rich glaze ingredients is a great place to start.

 

Applying glaze thickly does not, in and of itself, cause crawling.  It only increases the chances that a glaze whose recipe was already crawl-prone will manifest this trait.  Sometimes crawly glazes do not crawl, even though they will gladly do this when conditions are right.  For example, a mug with the same glaze applied all over and looks fine after firing, except in the right angles inside the cup at the bottom, where glaze runs down and gathers in the melt, and some crawling occurs.

 

Hard to say much more unless you know the glaze recipe (and the clay body recipe as well if possible!) and can make some adjustment.

[Marko]

How are you cleaning your pots? I use a damp sponge and then wipe and blow any sponge, dust or clay I might have missed. I also like to leave them overnight in a dust free cabinet. But I don't think you have to be that careful. It's just a habit I have, or a superstition, LOL.Hey, when you find the way that works, make sure you remember and repeat, hahah.

 

I can't help on the chemistry, as I am just learning myself. But if you buy premixed glaze and it doesn't work, maybe you could call your supplier and let them know, after you do another test. No ones perfect. I screwed up a batch once, okay twice, by not paying attention to the recipe. And forgetting what I just added. Argh! I now check off each ingredient as I add it. Oh, and very important, make sure you understand how your scale works, okay that was my third screw up. But that's it, honest. Just remember to have fun learning. The reward is awesome. Good luck Dave K.