Cold Porcelain - Proper Trials of Adapted Recipe

I went ahead and used my new cold porcelain recipe to make some pieces that I wanted to create moulds from – they were all about 1cm at their thickest point. The clay was fine to work with – smooth and pliable…BUT when I came back the following morning, there were cracks everywhere.

I did not dry them fast so that would not cause this. The thinner pieces – like the butterfly, had no cracks, but had fallen apart. I ‘glued’ it’s parts together with water.

So I cooked up a new batch of normal Cold Porcelain and mixed about 1/3 Normal with 2/3 New clay – made a second set of pieces…same problems.

Determined not to be thwarted, I then made a mix that was about 50/50 Normal/New…this made medium sized pieces and it had less cracks. The smaller butterfly was lovely – BUT I glued this one with glue and it still fell apart – Huh?!?

• So my recommendation is, you can add a SMALL amount of Whiting / Calcium Carbonate to your cold porcelain and you will find the results are just a bit more of a buff colour and that’s all.

• If you add it in any significant quantity, you may end up with cracks if you do larger items

• Larger amounts of Whiting are fine for thin pieces or small items.

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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:

Recipe

3 cups Cornstarch

1 cup of Whiting

1 cup water

1 ½ cups white glue

1 Tablespoon Baby oil

Method

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.

Conclusion

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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