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 :
- A thin disc with pressed texture ( I just used the edge of one of my molded polymer keyrings to make random texture)
- 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?
If you like this post – please do share it and you can subscribe for RSS or email updates so you don’t miss any new posts I make
Thanks for stopping by – see you again!