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Application of kiln wash


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#1 Nelly

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Posted 21 February 2012 - 10:32 AM

Dear All,

I just thought I would share with the group my experience in applying kiln wash to brand new shelves. I got some commercial kiln wash that came with my new kiln. I followed the directions carefully mixing it to the consistency of light cream.

Using a Haki brush I applied the coats as stated in different directions.

What I found was that cracking occurred on the shelf even before firing...???

I was sooooo frustrated. I couldn't figure out what I was doing wrong.

You see, I had three big shelves sitting on the ground in my studio. Sitting on cold concrete. After noticing crack after crack and non-adherence occur on the shelves, I washed it off, let it dry and then MOVED the shelves onto a table.

I am not sure if this movement away from the floor to a warmer temperature table had anything to do with it but the stuff took when this happened.

For me, the kiln wash was tricky stuff and other potters who I spoken with have said "it's a cinch, you should have no problems." But alas, I did.

I hope this is not a repeat of a previous post but just wanted to share this with you. If you have cracking kiln wash, try moving your shelves from the ground (especially if they have had a while to sit and absorb the cold), to a warmer table when applying the solution.

Again, I am not sure of the chemistry or why this improvement occurred but it did.

Anyone else have a similar experience. Very frustrating.

Nelly

#2 Mark C.

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Posted 21 February 2012 - 10:39 AM

I always heat my selves in the sun awhile before washing-I also make my own wash
I use a paint roller to apply often (2 coats dry between them) and let the sun dry them-then clean the edges with a scraper.
I'l post my formula when I get back from fishing
Mark

Edited by Mark C., 22 February 2012 - 12:01 AM.

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www.liscomhillpottery.com

#3 Nelly

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Posted 21 February 2012 - 10:48 AM

I always heat my selves in the sum awhile before washing-I also make my own wash
I use a paint roller to apply often (2 coats dry between them) and let the sun dry them-then clean the edges with a scraper.
I'l post my formula when I get back from fishing
Mark



Dear Mark,

Good advice. I now know this so when I have to make touch ups to spots where glaze may dribble that heating the shelves IS useful. I have made some cookies or various round flat surfaces for catching glaze that I will use on my shelves when glaze firing. So when and if glaze drips and I have to make some sort of patch on the shelf I will remember to warm them up. The cold just made the wash seize.

Nelly

#4 Matt Oz

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Posted 21 February 2012 - 11:16 AM

Hi Nelly,

Here are a couple of links to kiln wash articles from Ceramics Arts Daily, pretty informative.

Kiln Wash Simplified

The Many Layers of Kiln Wash: How to Find the Best Kiln Wash for Your Firing Temperature and Methods

#5 TJR

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Posted 21 February 2012 - 11:44 AM

Nelly;
Like you, I am a potter living in Canada. I have not had your experience with kiln wash cracking from the cold floor. When washing shelves, I use kiln wash quite a bit thinner than reccomended. This way you can add subsequent layers at a later date. Scrape your edges after applying.
My kiln wash recipe;
E.P.K 50%
Flint 50%
By weight. This wash is not good for salt kilns.Use in electrics or gas.
I find that most of the time I don't have to wash the shelves, as my glazes don't run.
TJR.

#6 Nelly

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Posted 21 February 2012 - 11:47 AM

Hi Nelly,

Here are a couple of links to kiln wash articles from Ceramics Arts Daily, pretty informative.

Kiln Wash Simplified

The Many Layers of Kiln Wash: How to Find the Best Kiln Wash for Your Firing Temperature and Methods



Dear Matt,

I have reviewed both of these excellent links. The conclusion I have come to is that while people say that kiln wash is a "cinch" it isn't. Such variation from person to person on what is best. I like the idea of only using the alumina hydrate and water.

In reading these posts, I also found the idea that chips can flake off and land on your pot slightly alarming. While I have seen this happen...I just know the mess I made of my new shelves with this wash and worry it will happen to mine.

I was just out in the studio and noticed that I do have drips around the edge of the shelves. I will take sand paper and/or a light dremmel and try to get these drips off. It would be incredibly disheartening to have chunks of this wash fly off during firing.

At this point, my shelves look okay. Still smooth but you can see where I had some trouble with overlapping and cracking.

The cookies I made to put on the shelves I have also covered with kiln wash. This wash took as I did this immediately after they came out of the kiln. They were likely around 200 degrees or so when I applied the wash.

At this point, my guess is that I do not have to rebake these cookies. I can simply put glazed objects on top of these baked and washed cookies and there should be no adherence of glaze if the bottoms are properly cleaned.

So yeah, kiln wash is NOT straight forward I do not think. Wish I had known all this before I struck out to wash my shelves. I guess all I can do is wait to see what happens with my glaze firing. Time will tell.

Nelly

#7 scoobydoozie

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Posted 21 February 2012 - 12:37 PM

This topic came at a great time. I just applied kiln wash to new shelves last week in FL and had them crack as they dried. I had them on the work bench in an air conditioned garage. Will try heating them first next time.

Question, though: Is all commercial ceramic kiln wash good up to cone 6 or is some only good up to 04? Not sure what kind I purchased from the local ceramic shop that fires to cone 04. PS - I fire in an electric kiln and only up to cone 6.

#8 Matt Oz

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Posted 21 February 2012 - 12:41 PM

I have used alumina on small shelves and it worked out pretty well, I did add some Elmers glue to the mix so it would stick to the shelf.

Sounds like what you have done is fine though, and I have put kiln wash on unfired clay and used it with no problems.

Good luck

#9 canyon fox

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Posted 21 February 2012 - 02:53 PM

I found this recipe the day :rolleyes: after I covered my new shelves with 50/50 Kaolin/ Silica wash:

http://jeffcampana.c...ling-kiln-wash/

#10 JLowes

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Posted 21 February 2012 - 03:42 PM

It could be the cold, or it could be dry shelves. I find that kiln wash applies much smoother for me when the shelves are slightly damp. So, I wet them down and wipe them down before applying the kiln wash.

John

#11 Pres

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Posted 21 February 2012 - 04:39 PM

It could be the cold, or it could be dry shelves. I find that kiln wash applies much smoother for me when the shelves are slightly damp. So, I wet them down and wipe them down before applying the kiln wash.

John


Seems like I run counter to most of the advice here. I have worked with commercial and formula types of kiln washes. In the past when mixing to cream like consistency or even house paint consistency I would have some cracking problems, and problems when repairing areas. Now I use my kiln washes very thin, build up several layers until the thickness I want. My shelves have a very even coat that protects, but does not flake as much as the thicker coats I used to use.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#12 Mossyrock

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Posted 21 February 2012 - 06:23 PM

When I first got my kiln, I mixed the kiln wash to the cream consistency (as directed on the label) and had the same cracking problem and it was very difficult to apply because it soaked into the shelf so fast I couldn't get a smooth application. I tried first with a brush, then with a paint roller. Finally thinned the wash, dampened the shelves, and applied a nice smooth thin layer. After that dried, I applied more thin layers. Worked great. My shelves were "room temperature".....seems it all had to do with the consistency of the wash.
Brenda Moore
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#13 bciskepottery

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Posted 21 February 2012 - 07:47 PM

Regarding chips flying, I try to practice the following steps . . .
When not in use, do not stack your shelves directly on the floor where they can pick up dirt and dust, get kicked, etc.; put a board underneath them.
Stack shelves on ends, not flat. You don't have to reach as far to pick them up. And, they are less likely to be hit with something and broken.
Stack shelves with kiln wash side facing one another,alternating with back sides facing one another; that prevents flakes of kiln wash from getting on the bottoms of shelves and falling on glaze ware.
Before putting a shelf in the kiln, sponge over the sides/edges, top and bottom to remove any loose flakes of kiln wash, dirt and dust.
If you end up with a glaze drip, set the shelf aside and take some time to remove it after unloading the kiln . . . don't wait until the next firing. And, resist the temptation (no matter how strong) to run you fingers over a glaze drop to feel if you've gotten it off or to feel if it is sharp; it is sharp and it will cut you and you will bleed. Regardless, keep a package of band aids handy.
Take care of your shelves and they will take care of you.




#14 Nelly

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Posted 21 February 2012 - 10:15 PM

I found this recipe the day :rolleyes: after I covered my new shelves with 50/50 Kaolin/ Silica wash:

http://jeffcampana.c...ling-kiln-wash/



Dear Canyon Fox,

I reviewed the step-by-step process of Jeff Campana. Wow, this guy is Alton Brown (from the food Network) of kiln wash.

This guy seems to really have it down to a science. Well done. I liked his idea in comparing it to white milk chocolate. I would, however, be much happier and feel safer if the wash was thin. Something about the build up of layers of wash does scare me in firing.

Funny that Jeff mentioned how he is particularly cognizant of his process as he uses porcelain. I watched a friend of mine lose a whole kiln load of porcelain fired work once as her feet or bases of her pieces stuck to the shelves. When we questioned our clay supplier about this breakage (like glass almost) he replied that it was likely some glaze not well removed from the bottom of the pot. But I just bet cha that it has to do with this kiln wash stuff. I mean, most of the studio was using stone ware.

While many variables could have been at play in this process of breakage, if nothing else, Jeff has made me understand yet another possibility.

Great blog he has.

Nelly

#15 bciskepottery

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Posted 21 February 2012 - 11:08 PM

Nelly,
A more likely cause of your friend's porcelain work sticking to the shelf is plucking -- where the foot rim or edge of the pot bottom sticks to the kiln shelf. Plucking occurs more frequently in porcelain that reaches vitrification.

#16 Nelly

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Posted 21 February 2012 - 11:24 PM

Nelly,
A more likely cause of your friend's porcelain work sticking to the shelf is plucking -- where the foot rim or edge of the pot bottom sticks to the kiln shelf. Plucking occurs more frequently in porcelain that reaches vitrification.


Dear Bciskepottery,

Now that is a term I haven't heard. I will go and look it up. It was, exactly as you said...the bottoms were sticking to the kiln shelf. The entire kiln load was ruined.

Thanks again,

Nancy

#17 Mark C.

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Posted 22 February 2012 - 12:51 AM

Back from Herringfishing-The ocean what a joy



A few points others brought up by others got me thinking a more detail description may help on wash

My recipe for wash hasevolved over the years and is geared for advancer shelves as I have about 60now in use

I have used silicon carbide/mullite/coralite/english dry pressed and advancer and Chinese advancer knock off shelves- over the years-I have not tried the new hollow core mullites yet

My wash recipe has variedfor some of these especially in my salt kiln

I’ll stick to reduction/electric high fire wash on all shelves-

Mullite.cordite is thirstier sucking up more than say advancers that do not absorb much

I’m not sure what shelve material you have the problem with but for most shelve wash I as others use it thin-as I roll mine with a paint roller with a medium to heavy stipple that process applies less material than a brush.

I mix my wash about like heavy cream which rolls on thin-I use two coats

I fire porcelain so plucking is always a concern-I like a wash that does not stick hard and I can repair easy-

Everyone has a different take on wash and mine is not the right or best or wrong way just the way that has evolved over about 40 years I have been at this-It works for me-It may not for you

The roller puts on a very even coat even with overlaps when wet-As noted I sun dry them 1sttgetting them warm then two coats getting dry between coats-scrap the edges as its easy at this point.

Then bisque them with pots on them before high firing them in a glaze with pots on them. Advancers are more sensitive to moisture explosion than some other shelve materials.

I store them (12x24) onend always stacked face to face-I do this with my mulite electric kiln shelvesas well (used only for occasional bisqueing)

This process lasts for many many years of firing-when I do rewash I lightly scrap or grind off this wash-as its easy to get off. -This is a key point

Wash recipe

50% alumina Hydrate

25% calcined EPK

25% EPK

Mix with water

This is not a cheap recipeand the calcining (bisque fired) helps control shrinkage
I calcine my own EPK in large bowl

I long ago use flint/silicain this mix but removed it in the early 90s

This works well for me afew potters I know-

Here is an old photo of about 50 shelves sun drying with this wash on them set up on my drying racks-whatever You can find!

also a glaze load with them in action.

I suggest you try a few first and see how you like this recipe.

Mark


Edited by Mark C., 22 February 2012 - 11:19 AM.

Mark Cortright
www.liscomhillpottery.com

#18 Nelly

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Posted 22 February 2012 - 04:27 AM

[quote name='Mark C.' date='22 February 2012 - 12:51 AM' timestamp='1329889865' post='13958']
Back from Herringfishing-The ocean what a joy



A few points othersbrought up by others got me thinking a more detail description may help on wash

My recipe for wash hasevolved over the years and is geared for advancer shelves as I have about 60now in use

I have used silicon carbide/mulite/coralite/english dry pressed and advancer and Chinese advancer knockoff shelves- over the years

My wash recipe has variedfor some of these especially in my salt kiln

I’ll stick toreduction/electric high fire wash on all shelves-

Mullite.cordite is thirstiersucking up more than say advancers that do not absorb much

I’m not sure what shelvematerial you have the problem with but for most shelve wash I as others use itthin-as I roll mine with a paint roller that process applies less material thana brush.

I mix my wash about likeheavy cream which rolls on thin-I use two coats

I fire porcelain soplucking is always a concern-I like a wash that does not stick hard and I canrepair easy-

Everyone has a different takeon wash and mine is not the right or best or wrong way just the way that hasevolved over about 40 years I have been at this-It works for me-It may not foryou

The roller puts on a veryeven coat even with overlaps when wet-As noted I sun dry them 1sttgetting them warm then two coats getting dry between coats-scrap the edges asits easy at this point.

Then bisque them with potson them before high firing them in a glaze with pots on them. Advancers aremore sensitive to moisture explosion than some other shelve materials.

I store them (12x24) onend always stacked face to face-I do this with my mulite electric kiln shelvesas well (used only for occasional bisqueing)

This process lasts for manymany years of firing-when I do rewash I lightly scrap or grind off this wash-asits easy to get off. -This is a key point

Wash recipe

50% alumina Hydrate

25% calcined EPK

25% EPK

Mix with water

This is not a cheap recipeand the calcining (bisque fired) helps control shrinkage

I long ago use flint/silicain this mix but removed it in the early 90s

This works well for me afew potters I know-

Here is an old photo ofabout 50 shelves sun drying with this wash on them set up on my dryingracks-whatever You can find!

also a glaze load with them in action.

I suggest you try a fewfirst and see how you like this recipe.

Mark


Dear Mark,

I just received the notice of your post. I can't believe the lengths people on this forum have gone to help me. THANK YOU.

Given that I had never done this before it was a bit daunting-not he mixing of the solution but the frustration of seeing the cracks and knowing this was not supposed to happen.

I appreciate you focusing on electric kilns in your post. I am using a fresh, out of the box Cone Art Kiln. I do not know the type of material in the shelves. This is an important point though. I just used the package of commercial wash they sent with the kiln. I thought it would be as easy as mix with water and apply. But oh no, it turned into a fiasco and who knows what the state of these shelves will be as I progress into the summer firings.

As I said, at this point, I have gotten rid of most of the cracks but there is a fragility to the surface.

I like to make large platters and usually put sand under each one in the middle of the shelf. But I also do some small work (i.e., mugs, vases, bowls) so the cookies are the way I have been taught to prevent glaze sticking.

Having said this, I have never worked with a digital controlled kiln. I always used the old ones with the cone sitter. I loved them. Seemed they were much easier to watch and control exactly what I was doing.

Having said this, I did figure out how to bisque the shelves after I washed them to the best of my ability without cracks. One turned out perfectly. The other two I had to scrap and try to repair or reapply wash.

I like your suggestion and Jeff's idea about using a roller. Makes sense.

Right now, I am working with the minimum number of full shelves (i.e., the three that came with the machine). I will be getting half shelves in the next few months so this recipe I will try.

I think, as I hear so many ideas on this topic, that I will keep a binder of the posted recipes. This way I can decide.

Believe me, when the cracks were happening with the wash, price didn't even enter into the equation. I just wanted the stuff to stick.

One thing I did not do was gently dampen the shelves before I used the wash. This could also have been an issue.

Maybe if I'd also warmed them slightly on a low candling temperature for an hour or so this may have helped too.

I just know that the world opened up for me when I moved the freezing cold shelves to the table and began application away from the cement floor.

I also liked your reminder and suggestion to me to stack the shelves face-to-face. It makes sense. I mean, good shelf preparation, including the posts is fundamental. I do need to invest in a grinding stone.

I am really particular when it comes to glazing and always, always ensure good clearance between my foot ring and the glaze. But the cookies are there for me to use in case glaze does run off.

I like to do platters that have many layers of glaze and/or slip. With my oxides, I will also be experimenting with spraying (that I now know to do somewhere outside and away from the grass). ;)

Thank you Mark for your reply. Really informative posting. Glad you had a good fishing trip.

Nancy

#19 neilestrick

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Posted 27 February 2012 - 06:36 PM

Kiln Wash 101
Neil Estrick
Kiln Repair Tech
L&L Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com

#20 SmartsyArtsy

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Posted 17 March 2012 - 06:52 PM

I am so grateful for all the advice in this forum. Although I am not new to ceramics, I have always been associated with an educational studio where techs took care of operational tasks. Spoiled, I guess, but I am excited to now having my own studio. So, just got my first kiln and I was able to apply much of the tips about washing my shelves. I am using the wash that came with the kiln (a Crucible 18 x 23) and will check in with my supplier to know what the mix is. I added just a bit of Feldspar to the mix.

My studio is in a garage in the NW so it has been cold at night. I heated the shelves in the kiln-- 88*F-- then wet them and applied several thin coats with a foam roller. Today we have some sun ante temp climate, so I put them outside half way through drying. They look great, but I hope there is enough on them--4 thin coats?

Thanks again everyone. I have a lot to learn about firing.




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