First glaze firing: wasters, kiln wash, warping?

[yappystudent]

A gap in my knowledge remains how to protect my standard kiln shelves and inside of the kiln. (Yes I know there are really expensive better ones, but I'm already into this for about 5k out of my savings, lets just chill on that notion for now) The manual explained kiln wash which is what I've used for it's test firing and the first bisque firing. Now I want to fill it with lots and lots of glaze testers that may run despite my clever design. Questions:

-Should I make wasters for everything?

-How do I remove the wash already on the shelves from the test and bisque firings? Should I remove it?

-Should I paint wash again for testing the glazes, and/or use wasters, both at once? The lady at the store told me not to use kiln wash so I can flip the shelves regularly to avoid warping, so she uses wasters, but wasn't sure how to answer my lots of little messy testers concern. 

-Speaking of wasters how thick should they be?

-Can they be any kind of leftover ^6, e.g. same cone I'm firing to, clay. Special shapes? 

[Mark C.]

Commercial wash is crap-make and use your own wash. There has been a lot of threads on this

yes try and get that crap they sold or gave you off your shelves-if it sticks leave it if you can sand it off do so.

wash mix

1/4 epk

1/4 calcined epk(you can buy this as glomax as well)or you can bisque your own in any form

1/2 alumina hydrate

mix like heavy cream-I roll it on but you can brush it.

I'm not a cone 6 person so waster s are not what I will advise on -but for glaze testing yes use them and that can be whatever thickness you want . to thin and they are hard to handle-to thick same deal.

 

[neilestrick]

Use wash, keep it on there until it's so bad you have to grind it down. Touch it up as necessary, add more if needed.Use wasters for glaze tests. Yes, you can reuse them.

[hitchmss]

One thing I picked up regarding kiln wash; from kiln master at homer laughlin factory. To keep wash popping loose from shelf and flying around their turbulent kiln (and consequently when handled in/out, etc) he would add enough G200 to the wash mix that it was hard enough after firing that his finger nail would no longer dent the surface, but a key/nail would scratch it still. For me in my cone 12 kiln I would use 1.75% G200. I second Marks recipe; 25% Calcined EPK helps keep it from shrinking too much and flaking off. Before I got my advancer shelves my cordierites had a build up of maybe 3/8" thickness of kiln wash; when glazes ran they rarely made it through the layer to stick to the shelf. Touched them up between firings. I didnt flip my shelves; no amount of flipping will keep shelves flat at cone 12+, but if needed to, a drywall knife, or angle grinder with a wire brush attached could remove the fired wash easy enough. Do this outside, with plenty of ventilation, wear a mask, and make sure your and your neighbors windows are closed first!

 

[Callie Beller Diesel]

I think the question of wether to wash or not depends on how much you’re experimenting with your materials, and how well you know them. Kiln wash is meant to be a safeguard against small mishaps and application errors. It will not save shelves from epic runs. If you’re just worried about glaze test drips, you can reuse waster slabs that don’t get damaged. 

I don’t have fancy kiln shelves either, and I put a layer of the wash recipe Mark mentioned on them. They have not yet warped after a year and a half of firing to cone 7 in an electric kiln. As the kiln is in an outdoor shed, I don’t have a vent on it, so there’s no draft to pull wash loose to worry about.  The warping process may take longer than that to occur, I don’t know, but so far so good. 

[oldlady]

many years of kiln wash of the wrong kind and several years of mark's recipe tells me that the new recipe wash is excellent insurance.  the old stuff kept flaking off with every firing, i have no flakes of any kind since applying the new stuff.  my shelves are of various ages, some back to the 1970s that came with an old kiln given me by a retiring potter.  the warped ones have a dip in the center so i fill that dip with silica sand to level it off.   works fine.