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Benzine

"aggressive Cleaning" Of Ceramic Paint Palettes

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So, this past year my Painting class had some extra time, so I decided to do an oil painting unit.  I didn't want to get the oils on my normal classroom palettes, which are plastic.  I didn't think the oil would come off them well, and was also worried about the oils eating through them as well.  So, I had a couple students make me some ceramic palettes, for the class to use.  Unfortunately, we didn't have time to get a coat of clear or white glaze on the top, to make them easier to clean.  So we ended up just using the bisqued versions.  They worked well enough, but obviously, the oils seeped in the porous bisque.  

 

I would still like to glaze them, for next year.  How much smoke, would burning oil paints produce?  Would the resulting smoke and residue, be bad for the kiln's elements?  

 

I could alternately use my Raku kiln at home, which I would fire outside.  The only issue with that is the clay body is a low fire earthenware.  So I would have to go pretty slow, to avoid shattering the palettes.  But I would imagine, the oil paint is going to burn off, at a relatively low temp.

 

So would this be worth doing, or just avoid the hassle, toss the old palettes and make new?

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I'd be worried about some of the pigments remaining behind once the oil base is burnt out. Things like cobalt, iron, titanium and cadmium are used in all kinds of paints, as well as ceramics, and might not burn out. It might just be less work to make new ones.

 

My high school used clear glass pallets with tape around them to prevent chipping, even though we used acrylics and not oils. They were really easy to scrape with a razor if stuff got too dried on.

Chilly likes this

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The paint pigments, are a very real concern.  However, I'll be honest and say that I didn't go all out on the oil paints.  So the colors aren't as "pure" and aren't the Cadmium Red or Yellow, or Cobalt Blue, that are considered to be the purest version of each.  I'm not saying the paints don't contain other such materials, and I'll definitely look closely at the labels.

 

Yeah, my original goal, was to make something akin to glass palettes, with a smooth glazed ceramic surface.  Time caught up to me though.  I had the students put thick raised rims on them, so they are fairly chip and drip resistant.  

 

We mainly use acrylic and watercolor, but I saw an opportunity to expose the class to oils, and went with it.  The plastic trays we use for acrylics clean easy, especially if you let them dry.  Then they peel right out.  I don't think the dried oils would do the same.

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Some years back I used commercial low-fire clay bodies for raku without any problems.  Cracking during raku firing is more about abrupt changes in thickness and uneven heating due to placement in the kiln than any other aspect.  I have also used artist oil paint as a glaze resist for raku.  The 'paint' keeps the raku glaze from adhering and burns off leaving a bare clay to absorb soot in the reduction chamber (and sometimes a 'tint' when there is no soot).

 

I have also used oil and acrylic paints as sources of metals for making marks on high fire work.  Recently did an experiment with about 10 different acrylic and oil paints to produce color in fused glass; some made good marks, some did not.  I made my choices by looking up the pigment codes that are on every tube or box of artist paints and matching them to metallic elements.    Cobalt, iron, titanium, zinc, and copper are the common elements.  The pigment codes are standardized by ASTM and other organizations; there are tables on the internet matching pigment codes to the detailed chemical names of each pigment if you want to dig deeper into the details. 

 

The only way to know what mark the pigment leaves is to try it.    If you place an opaque white low fire glaze over the re-bisqued palette, you probably will have a workable artist palette after a glaze firing.

 

LT

Marcia Selsor likes this

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This is what I would do ... probably ... of course you absolutely must do what you feel is safe. 

 

1. I would scrape the excess off as well as possible. I've used boiling water to soak layers of oil paint off of things before so I would probably try that. 

 

2. Bisque fire to burn off any residual oils, leaving vent plugs open and firing  s l o w l y. 

 

3. Glaze black to cover any stains left over. (unless there's some reason to NOT have a palette in black)

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3. Glaze black to cover any stains left over. (unless there's some reason to NOT have a palette in black)

 

I don't even like to make tea in a cup or mug that isn't white inside, I am only a very occasional and very amateur painter but I also couldn't use anything but a white palette.

 

It's like how glazes appear different on different clay bodies, if the paint is going onto a white ground it has to start on a white palette.

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At our local centre we use tin foil wrapped around wall tiles for paint palettes.  When finished with, the tin foil gets thrown in the bin, the tiles are put back on the shelf for next time, so very little paint gets washed down the drain.  

 

As above, can't imagine that firing the bisque palettes would remove all residues - start again or rethink.

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3. Glaze black to cover any stains left over. (unless there's some reason to NOT have a palette in black)

 

I don't even like to make tea in a cup or mug that isn't white inside, I am only a very occasional and very amateur painter but I also couldn't use anything but a white palette.

 

It's like how glazes appear different on different clay bodies, if the paint is going onto a white ground it has to start on a white palette.

I can understand not having it on a color but it wouldn't bug me to have it on black. But I hate white interiors on dishes so I guess that makes sense. Lol

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Unless these are pretty fantastic amazing palettes make new ones. I'd expect the smoke would be wear and tear on the elements similar to a reduction fire in an electric kiln. Firing in a raku kiln would burn off the organics, and potentially leave the colorants. So then you would need to coat them in a white underglaze, assuming you want a white background for the colors, then you would need a clear glaze protecting it. 

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At our local centre we use tin foil wrapped around wall tiles for paint palettes.  When finished with, they get thrown in the bin, so very little paint gets washed down the drain.  

 

As above, can't imagine that firing the bisque palettes would remove all residues - start again or rethink.

Assuming Chilly means 'throw the foil in the bin,' I vote for this. If you love the raised rim, and I think you do, use your palettes as is, covered in foil.

Chilly likes this

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At our local centre we use tin foil wrapped around wall tiles for paint palettes.  When finished with, they get thrown in the bin, so very little paint gets washed down the drain.  

 

As above, can't imagine that firing the bisque palettes would remove all residues - start again or rethink.

Assuming Chilly means 'throw the foil in the bin,' I vote for this. If you love the raised rim, and I think you do, use your palettes as is, covered in foil.

 

 

Yes, sorry, wasn't very clear.  Throw away the tin-foil, keep the tile for next time.

 

(Edited post #9 above to make it clearer.)

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