Seedy Potter reacted to Mark C. in Cleaning Kiln Wash Off Kiln Shelves
First if this is commercial wash its usually made with cheaper products and in my option you can make a better wash yourself(see other kiln wash posts in the search function)
second if its cracking its to think-you need to thin it.
Third if the shelve is molding (green) its to wet and needs to be dried out (I do know where you live for climate issues)
I would bring off all this wash make your own dry shelves and start over.
but thats me
Seedy Potter reacted to Benzine in Cleaning Kiln Wash Off Kiln Shelves
The only times I've had kiln wash crack, is when I apply it too thick. Imwould say, I apply mine a bit thinner than half and half consistency.
I do three coats, and the first coat looks like I've barely put anything on at all. And that's why I used to have cracking issues, because I thought each coat needed to be thicker to protect the shelf.
Seedy Potter got a reaction from Chantay in Large Flat Pieces Cracking During Glaze Firing
I am having trouble with successfully firing large flat pieces in a glaze kiln. When I bisque fire them, I put a little sand under them to reduce the friction on the shelf as they shrink and move during firing. This has been very successful. However, I am hesitant to put sand in a glaze kiln especially with a vent master drawing air downward. I am afraid that the sand will be drawn into molten glaze. My question is: is that a reasonable concern? If so, what would any of you suggest to use to keep large pieces from breaking apart at ^6. Might the problem be solved if I brought the kiln temp up much more slowly? What temp range is the most critical?
Is it possible that all the moving sand will have "found a home" by the time the glaze is molten? This still feels if-y to me... I could use some sage advice!
Seedy Potter reacted to bciskepottery in Large Flat Pieces Cracking During Glaze Firing
You should be okay using sand during the glaze firing, too. Just make sure you leave some space between the sand and where your glaze starts. The vent should not be moving the sand around during the firing. Options to using sand include clay cookies allow the platter to sit above the kiln shelf, clay slats, or clay coils. But the key is to get the platter/flat item above the shelf so it cools evenly. The kiln shelf retains heat and cools more slowly as it is thicker than your pottery (except for sculpture). Allowing the item to cool above the shelf minimizes the chance for uneven cooling and cracking.
Seedy Potter reacted to neilestrick in Solutions For Flaky Kiln Wash
If the formula is high in kaolin, like over 20%, you'll need to calcine some of the kaolin. I would leave 10% normal, to help keep the wash suspended in the bucket and make application smoother. To calcine, just put a bunch of kaolin in a bowl and run it through a bisque. Kaolin shrinks when fired, and that's what makes it flake off. By calcining, you pre-shrink it.
Seedy Potter reacted to JohnDonovan71 in Solutions For Flaky Kiln Wash
I have been using a 50/50 silica & EPK kiln wash recipe (by weight), firing the EPK in big bisque-fired bowls before mixing. I also started mixing it much thinner last year, like skim milk thin, and applying 2-3 thin coats. My kiln wash flaking pretty much went away after I made those changes!