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New Kiln Wash Application


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#1 SueDNim

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Posted 19 February 2017 - 07:49 AM

Good morning, I am new to electric kiln firing and as such kiln wash. Bought some that was mixed from a local studio and applied 3 coats. First one may have been a little thick so I thinned up the latter coats. After drying each layer I have noticed some cracking on the surface. What should I do ? Should I sand it till no longer visual. It is sparatic on some but not all of the shelves.
Planning on doing a bisque fire soon.
Thanks so much for help !!

#2 Mark C.

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Posted 19 February 2017 - 09:04 AM

I would sand or scrap it all off before firing it. It comes off easy now. Thin the wash and apply two thin coats. It's cracking now as it's to thick.let it dry between coats. Most apply wash two thick and it cracks.
Mark Cortright
www.liscomhillpottery.com

#3 SueDNim

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Posted 19 February 2017 - 11:15 AM

Thanks so much, looks like some light sanding took care of it.
I will definetly go thinner next time.

s.

#4 Marcia Selsor

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Posted 19 February 2017 - 11:17 AM

I agree. You should apply kiln wash using a very thing coat. The shelf will suck the moisture right out of the wash making it go on thickly if you don't thin it down. Then you'll get flakes inside your glaze ware.
Marcia
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#5 Min

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Posted 19 February 2017 - 12:39 PM

A lot of kiln wash is made to be as cheap as possible. If you find your wash is flakey after firing you might want to mix up your own. 

 

This works well:

 

50 alumina hydrate

25 epk

25 calcined epk



#6 Marcia Selsor

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Posted 20 February 2017 - 08:41 AM

I use
1/3 kaolin and 1/3 silica and 1/3 alumina. I fire porcelain in oxidation and don't want the foot of the porcelain to grab the shelf. Alumina prevents that.
Marcia Selsor, Professor Emerita,Montana State University-Billings
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#7 Mark C.

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Posted 20 February 2017 - 08:41 AM

Best to make your own with above recipe as Min says
Mark Cortright
www.liscomhillpottery.com

#8 Dick White

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Posted 20 February 2017 - 08:55 AM

Something I stumbled upon when starting out, but have not seen it discussed by the experts - I originally used a recipe similar to the one Marcia posted, and sometimes had serious peeling and other times not. Then I noticed that the peeling shelves were all ones laid flat on the table and left to dry while the non-peeling ones were leaned against the wall at an angle, exposing the back side as well as the front side. I assumed it had something to do with allowing moisture to penetrate through the shelf and evaporate from the back rather than all of it needing to come back out only the front after the coating of wash on the surface was already dry. I now always prop the freshly washed shelves against something while they dry. I have also changed my wash recipe to one Min suggests to eliminate the silica and replace half the kaolin with calcined kaolin to eliminate shrinkage. Have not had any problems with this.



#9 Dani

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Posted 20 February 2017 - 10:50 AM

Does the surface of the shelves affect the flaking of kiln wash? The shelf where this keeps happening appears to be more smooth and vitrified than the other shelves where flaking does not happen.

#10 Joe_L

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Posted 13 March 2017 - 03:43 PM

Thinking of buying another shelf for more options when packing. Does a newly Kiln Washed shelf need to fired first before use, or is it ok to put ware onto the fresh wash?  I'm using commercial kaolin/al hydrate premix. Assuming also I can trust my glazes enough not to run before the shelf is protected.

 

Joe



#11 Joseph F

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Posted 13 March 2017 - 03:56 PM

Thinking of buying another shelf for more options when packing. Does a newly Kiln Washed shelf need to fired first before use, or is it ok to put ware onto the fresh wash?  I'm using commercial kaolin/al hydrate premix. Assuming also I can trust my glazes enough not to run before the shelf is protected.

 

Joe

 

If your glazes don't run and you have used them a lot(trust) then you don't have to have kiln wash. I am buying three new shelves for plates and I have no plans on putting kiln wash on them as the glazes I will use for plates will not run. I think several potters here don't use kiln wash on their shelves because they work with the same glazes for their production and they know it won't run.

 

This might not be true if your using porcelain compared to stoneware as some porcelain can get sticky and parts of the feet can stick to the shelves.



#12 neilestrick

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Posted 13 March 2017 - 05:13 PM

If your stoneware fires really tight then it can stick some, too. Alumina in your wax is a good solution if you don't want to wash the shelves.


Neil Estrick
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Owner, Neil Estrick Gallery, LLC
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#13 Pugaboo

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Posted 13 March 2017 - 08:49 PM

I use Highwater Clays cone 6 Little Loafers white clay and it will definitely pluck if I don't wax, kiln wash and sometimes even use kiln washed cookies so the amount of foot ring in say something like a large platter is limited in its contact with the shelf. I don't have any real issues with my glazes since I know them and am real careful but I am getting ready to redo the kiln wash on all my shelves because I have noticed it is starting to flake off more and more.

T
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#14 Mark C.

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Posted 13 March 2017 - 08:50 PM

I like my cookies without wash and just a glass of milk.


Mark Cortright
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#15 Joe_L

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Posted 14 March 2017 - 05:02 AM

Thanks Joseph for reminding me that wash is optional. 

 

I DO want to wash the shelf so that it is prepared for any glaze drips in subsequent firings. My question was whether I can put some (trusted drip-safe) ware on the unfired kiln wash the first time its fired or whether the wash MUST be fired without ware initially.

 

The kiln wash mixture has kaolin which I guess acts as a binder to keep the alumina hydrate attached to the shelf so if I put ware on before it has fused during the shelf's first firing I don't want it to bind to the ware as well. I imagine a problem is unlikely as conditions in the foot ring/kiln wash/shelf contact area will be the same in all the subsequent firings.






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