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Seedy Potter

Cleaning Kiln Wash Off Kiln Shelves

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I have never had so much trouble with kiln shelves.  I am wondering if I have done something wrong.  

 

I had all the shelves in my set to clean and apply kiln wash.  It was daunting task with the pumice stone and chisel. So I used my orbital sander and it went so fast that I am wondering why I've never seen anyone suggest it. Then I put kiln wash on all of them. I thinned the wash (as I have learned that it must be as thin as half and half milk).  Brushed it on in different directions to get a complete coverage.  This has worked every other time I've done it - until now.  After the 3rd coat, about half of the shelves had the wash crackle and fall off. I washed them clean and reapplied.  This time fewer of them crackled.  Cleaned them and re-applied.  This time I'm down to 3 that crackled. Couldn't get 2 of these to hold so I cleaned them very well spraying them with water to make sure there was no dust on them, let them dry in the sun,  and turned them over.  When they were dry, one of them turned blotchy green - mold??? I applied kiln wash.  It didn't want to stick to the green areas, but eventually I got 2 coats to stick.  I plan to fire these last shelves in my next glaze kiln.  

 

This is so crazy.  I've never had these problems before. Has anyone else experienced these problems?  Any ideas what is happening here?

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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.

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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

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Yea, Mark.. .It's a commercial wash.  I think I'm convinced (especially after read the Jeff Campana article - http://jeffcampana.com/self-leveling-kiln-wash/) that I definitely need to start mixing my own wash.  I'm hoping I can get the ingredients locally.  And the last two shelves were successful, I think because I watered the wash down to almost skimmed milk thickness.  I'm wondering if that shelf that I had get moldy was one of the new ones I just bought.  I'm thinking that I need to fire or at least do a thorough job of drying all shelves before I try to apply wash.  I used to simply put them in a kiln firing as soon as I got them, but this one was one of 2 I recently bought and it's hard to know how it was stored before I got it. 

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My wash is 1/2 alumina hydrate 1/4 epk 1/4 calcined epk (calcined just means you bisque it to whatever you bisque to)

It been a great wash for 40 years.

I use a paint roller-just search for a post with photos of the shelves and washing

 

http://community.ceramicartsdaily.org/topic/3025-kiln-wash-application-on-a-sunny-day/?hl=%2Bkiln+%2Bwash&do=findComment&comment=107150

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