Tuesday, August 4, 2009

New Experiments in Cold Porcelain – New Recipe

I decided to try an additive in my Cold Porcelain recipe for two reasons – I wanted something as a filler that was less expensive than cornstarch and that would reduce warping and / or shrinkage of thin pieces.
Having used Calcium Carbonate in the form of Whiting – easily gotten in our local gardening shops here or through pottery suppliers in some countries – in papermaking as an acid neutralizer and to reduce sheet warping and give a certain smoothness to our papier mache pulp mix, I figured it would be a good candidate.
So first of all, I took some old Cold Porcelain I had knocking around and added in some whiting by kneading it in. It worked fine, I didn’t add much and the results were pretty much the same as the normal mix.
Yesterday, I decided to take it a bit further, so I added a larger amount into the mix and cooked it with. Here’s the recipe I used:
3 cups Cornstarch
1 cup of Whiting
1 cup water
1 ½ cups white glue
1 Tablespoon Baby oil
This I cooked in a pan on the stovetop. It took about 10 minutes on the lowest setting, stirring constantly and making sure to scrape from all parts of the pan.
Worth noting, I did not use a non-stick pan: You do not need a non-stick pan after all - as long as you are prepared that the cold porcelain will stick to your pan and you soak it off afterwards. Granted Non-stick is much more convenient! 
Testing & Observations 
My observations are that the mix was very sticky as I stirred it, but it came together fine and formed a ball that was not sticky to my fingers. It kneaded up fine with the normal amount of cornstarch on my hands.
I made two test pieces :
  1. A thin disc with pressed texture ( I just used the edge of one of my molded polymer keyrings to make random texture)
  2. A little humming bird using the Dolphin Tutorial method adapted.

I put them to dry in the window where they got sun – same as I do with all my things when I’m being impatient. 
  • The thin pieced warped plenty!
    Note: flatness is MUCH easier to achieve if you dry slowly, turn often and if possible, restrain with some form of flat weighted object on top – it doesn’t have to be very heavy, in fact if it’s too heavy, your texture will be smooshed. Experiment with what works
  • The shrinkage was NOT less than my normal recipe – I didn’t measure, but it actually looks like more shrinkage to me
  • The strength is a little reduced – the piece broke fairly easily
  • The translucency was NOT reduced. This surprised me, as whiting is an opaque additive
  • The colour was much more buff than the normal recipe
  • I should’ve sifted the whiting – the lumps do not easily knead away and can be seen in the translucent parts as well as in the surface.
I am fairly happy with Whiting (Calcium Carbonate) as an additive – I might try reducing the amount a bit, and I will sift it in future. I like the texture for working and am happy with the buff colour too – more bone-like.
What about  you? Have you a favourite Cold Porcelain recipe?

Have you added interesting things to your Cold Porcelain?
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Beth Harris said...

I had the same thoughts as you (which is how I found your site - Google'd cold porcelain additives)

I used plaster of Paris though and kneaded it into cold dough from the day before. I kept kneading till it felt like stiff, dry-ish pastry dough. About 1-1/2 TBL spoons to a piece the size of an apricot.

The curling is less... especially on the lightly weighted piece and I made a drying platform out of thin fine birdcage wire so the air can get underneath and dry both sided more evenly.

The finished piece is a bit heavier...which is good, and it still holds the details well. It isn't perfe t yet, bit it IS better.

I'll let you know when/if I perfect the additives or find a better recipe.

Anri-Irene said...

Hi! I have a few new recipes for cold porcelain! http://anri-irene.blogspot.hu