Kiln Shelf Prep the Easy Way
When glass is fused together on a kiln shelf, there needs to be a separator between the glass and the shelf. One way to do this it to prepare the shelf with kiln wash. This prevents the glass from sticking to the shelf when it heats up and fuses together. Sort of like flouring your pastry board before rolling out a pie crust. What you don’t make pie crust?! I don’t either anymore. Preparing the kiln shelf is not a particularly fun thing to do.
Initially, I followed the instructions in the books I read. They said to use a putty knife to scrape the shelf, and a Haik brush to apply kiln wash. Eight coats of the kiln wash in different directions was the recommendation. But now I use a wide razor to scrape off old kiln wash – more effective than a putty knife*. To remove random bits of kiln wash on the shelf I use a green scouring pad. Sometimes I use a spongy sanding blocks, however, you have to be gentle. To aggressive with the sanding and you can put a divot in the shelf where air can get trapped under the glass. In any case, I don’t worry about getting off every last bit of kiln wash anymore.
To apply the kiln wash I use either a Haik brush or a cheap chip brush (it doesn’t loose as many hairs). Four coats of kiln wash is all I do these days. If I’m being really conservative I’ll put on 6 coats. And I am way not as meticulous with this as I was when I first started out. When I brush on 6 coats I can usually get two firings out of the shelf.
I know some use kiln shelf paper as a quick and easy kiln shelf separator. There is no denying that it is convenient, quick, and easy. I do use it on occasion, mostly when I am doing a commission piece, or when firing opalescent glass very hot and long and I want to make sure the glass doesn’t pick up kiln wash. However, you pay for that convenience. For comparison, kiln wash can cost less than 50 cents to coat a shelf. Kiln shelf paper will cost anywhere from $2 to $5 a sheet depending on how many you buy, whether or not you catch a sale, and if you pay shipping.
Anyone have any other kiln shelf prep tips they’d like to share?
Tip: Tape two Haik brushes together with some duct tape to get a super wide brush. In the picture below I taped the widest brush I could find with a smaller one. I put my kiln wash in a rectangular glass dish and can now kiln wash my 21 in shelf in three strokes.
*Update. I have tried using the edge of a piece of scrap glass to scrape off the kiln wash as suggested in one of the comments, and it works well.
you don’t need as much or thick of a coat. it’s a separator, so you need only as much as it takes to act as a barrier. the hotter you go, the thicker the layer you need. my normal fusing temp is 1430 so i go on the thin side.
i typically don’t scrape until i get a ding in the surface; something sticks and i pull up a chunk of the wash. if that’s in an area i can ignore, i still don’t scrape. i just put a couple (at most) of thin layers on what’s already there and it’s good to go.
also, you don’t have to really scrub off every last bit. as long as it’s smooth, the remains of the previous coat are just covered by the new coat.
if i’m using fiber paper for any reason, i don’t bother putting new wash under that. the remains of the previous coat are just there for protection against mishaps.
i have a fiber shelf for bigger things. you can’t scrape those type of shelves, so i usually just add more wash onto whatever is there. if i have a ding in the wash, i either fill with a paste of wash instead of thin layers, or i sweep off my driveway well to get all the gravel off it, then use it as a flat lap to remove old wash and even out the surface again.
I use the straight edge of a scrap piece of glass to scrap the old kilnwash off of the kiln shelves. Trying to fire as low as I can to get the effect I want, I have been able to fire a surprising number of times before having to redo the kilnwashing of the shelf.
Zane, Thanks! ‘m going to try the glass idea. I’d be thrilled if I could get three firings out of it. May have to experiment with lowering my process temp.
I want to let you know that i prepare my self with something else.
I put 50% koalin and 50 % plaster together in a tupperware and mix that.
Than i scatter it on my self and make it flat.
So your ready and can use it. For several times.
Every time you miss a little bit, scatter new misx and make flat.
I make ik flat with an ordenairy paper.
I hope you understand my englische because i am from holland.
Thanks for sharing Ursula. Some day I’ll have to try that. I visited Holland for the first time this past summer. Had a great time!