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waterproofing raku

updated thu 14 feb 08

 

Suanne Muehlner on thu 25 apr 96

Something like Thompson's Water Sealer is an effective water proofer for
raku pots meant to hold liquid, like flower vases. I always include a note
to the effect that raku pieces are not to be used for food or drink and
that a sealer has been applied.

From Central Maine where the last snow pile on the north side of the house
melted yesterday. Suanne Muehlner

Casey Savant on mon 11 feb 08


Hi everyone, can anyone tell me the best way to waterproof raku and
smoke fired pottery

vpitelka on tue 12 feb 08


Casey wrote:
"Hi everyone, can anyone tell me the best way to waterproof raku and
smoke fired pottery"

Casey -
The only way to waterproof them is with plastic coatings, and then you are
coating your fired ceramic work with plastic. Do you really want to do
that? Generally-accepted theory is that the only time it is even
appropriate to do that is with a vase, a covered box, or some other form
that will never be used for functional food-contact applications.
- Vince


Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka

Bruce Girrell on tue 12 feb 08


We use Thompson's Water Seal. We use the original version, not the new
water-based stuff, which we found to be difficult to work with. We fill the
pot with the product, let it sit for a few seconds and then pour it back
out, rotating the piece to coat the entire lip. We sop up the excess with a
rag and then use that to coat the outside of the pot. Wear rubber gloves.

With horsehair pottery (no glaze at all, low bisque temp, and very, very
porous) the product works very well. We have filled the pots with water and
let them sit for a weekend with no sign of leakage.

We have not done tests with aged pots. In other words, I have no idea how
long the protection will last.

I have not tested the product on anything with cracks that penetrate the
entire thickness of the pot's wall. We consider those as rejects. However,
with glazed raku, there may be some pots with small through-wall cracks that
are keepers. I suspect that the product will seal small through-wall cracks.
Temperature cycling or other effects could re-open the cracks, though.

I do not know what effect the product will have on something like a copper
matte. Normally, we buff off the excess - not something I would try for a
crusty glaze. If you do use copper matte or other rough glazes, do a test
first on one of your less than gorgeous pieces. If the product is not
applied too thickly, it should dry clear, not white.

Bruce Girrell

William & Susan Schran User on tue 12 feb 08


On 2/11/08 10:07 PM, "Casey Savant" wrote:

> Hi everyone, can anyone tell me the best way to waterproof raku and
> smoke fired pottery

Masonry & grout sealers have been used with success.
Bill

--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com

Tony on tue 12 feb 08


Thomson's water seal poured into the pot then poured out again. Repeat daily
for several days.

--------------------------------------------------
From: "Casey Savant"
Sent: Tuesday, February 12, 2008 2:07 PM
To:
Subject: waterproofing raku

> Hi everyone, can anyone tell me the best way to waterproof raku and
> smoke fired pottery
>
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Lee on wed 13 feb 08


I would like to take time to point out something here, because I think
the talk about having to seal raku leads to the mistaken idea that all
raku has to be sealed.

Traditional raku and raku I make do not need to be sealed any more
than anyother kind of functional ceramics. It is all a matter of
using a glaze that fits and avoiding the thermal shock of quenching
work in water.

--
Lee in Mashiko, Tochigi Japan
http://mashikopots.blogspot.com/

"Tea is nought but this: first you heat the water, then you make the
tea. Then you drink it properly. That is all you need to know."
--Sen No Rikyu
"Let the beauty we love be what we do." - Rumi

Joseph Herbert on wed 13 feb 08


Casey Savant wrote: Hi everyone, can anyone tell me the best way to
waterproof raku and smoke fired pottery

While not really being responsive to Casey's question, I would say the Best
way is to refire to cone 10.

The problem here is the lack of realization that the techniques indicated
are not intended to produce vessels in the normal sense of the word. They
produce objects that are shaped like vessels serving as a substrate for
decorative applications of various materials. The fact they are shaped like
vessels misleads many into thinking they actually are. Not so. Asking how
to water proof pottery demonstrates the object is, in fact, not pottery
Fired clay to be sure, but vessel, probably not.

Joe

Joseph Herbert
Technical Writer
Irving, Texas
214-725-8305 (Cell)


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Taylor Hendrix on wed 13 feb 08


Hey Casey,

I don't know if this is the "best" way to waterproof raku ware, but I
have successfully (I am so ashamed of myself) waterproofed a saggar
fired bud vase made for Mayor Mel with tool dip. Yes, tool dip. I
thought it would be soooooo attractive to Mel, but I chickened out on
taking it to NCECA last year for fear the solvent fumes would
encourage airport security to cavity search me. I'm just waiting for
Mayor Mel to ask for me to send it on to him. The yellow tool dip
really sets off the surface colors nicely.

Taylor, in Rockport TX

On 2/11/08, Casey Savant wrote:
> Hi everyone, can anyone tell me the best way to waterproof raku and
> smoke fired pottery

Marcia Selsor on wed 13 feb 08


Personally,
I don't feel raku should be sealed either. But if one uses a high
content of copper in a finish..beyond 5% according to Tom Buck, the
color will oxidize.
So, for that purpose, maybe someone would want to arrest a color by
putting a sealer on it.
I would never apply a sealer to a surface where they would be ingested
-> food or drink.
I have put light acrylic medium with UV protection on top of some of
my slab pieces and tested them outside in the long summer sun of
Montana for over 8 years. They did not fade where coated.

Marcia Selsor
Brownsville, TX
http://marciaselsor.com