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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HOW TO MAKE COLD PORCELAIN

Cold Porcelain is available as a commercially made mix you can buy - but you can also make a similar clay yourself from three simple ingredients. This clay is fun to use, dries super hard and can make solid chunky pieces or wafer thin translucent pieces. You can colour it with paints or paint on it when dry - add glitters, sand, etc and it sticks easily onto wood or glass to decorate items. Varnish to make fully waterproof.

So, let's make cold porcelain -

Recipe

The recipe will be different depending mainly on the brand of glue you use – for this one I used Elmer’s Glue-All – a white pva glue.

Ingredients

2 cups Glue
½ cup water
3 cups cornstarch
2 tablespoons baby oil

Tools

Plastic microwavable bowl
Strong wooden spoon or flat stick
Cup and Tbs measures
Spatula or blunt knife

Method

Put all the ingredients in your plastic microwavable bowl, stir together until they are fairly well combined.

Note, you don’t need to sieve the cornstarch and you don’t need to mix until it’s really even – just break up any big lumps.

Pop it in the microwave -

NOTE – all microwave ovens are different – some cook super fast, some very slow.

Your cooking times will also depend also on the size of your bowl in relation to the amount of clay you are making – big bowl, little clay, it may take longer, big bowl, lots of clay may be slow at first then cook really fast once it gets hot.

So, err on the slow side at first – I do 1 min @ 10% or the lowest setting first – if it is barely warm I move to 1 min @ 30%.

Each time you finish a microwave session, take the bowl out and stir the clay – as it cooks the edges with harden first so it’s important to scrape them and stir them in.

You don’t need to make a smooth paste, just break up lumps and pull in the edges to into the mix.

When the mix starts to get significantly thicker, harder to scrape off and stir, shorten your microwave times to 45s

It should take about 4-5 minutes in all to get to the point where the mix sticks to the spoon/stick. As it gets thick enough to hold it’s own shape but will still stick to your finger when you touch it, shorten your times to 30s

When it's ready it will hold fairly well together when you mix it in the bowl and it will not stick to your fingers anymore when you press your fingers in.
BUT it's okay to take it out when it's still a little sticky and knead in more cornstarch: In general, it's better to UNDERcook a little than to overcook.

Now you are ready to take it out of the bowl and knead it.

Sprinkle a generous layer of cornstarch on your table and over your hands.

Turn out your lump of clay, scrape the sides and bottom of the bowl as best you can, then sprinkle some cornstarch in the bowl and scrape some more – the rest will come off more easily as the cornstarch dries it.

Don’t worry if some is left back – let it dry and then it will peel off very easily – this is my recommended clean up method.

If you choose to wash out your bowl, make sure you allow a lot of water to flow so the gluey mix does not clog your drains.

But, don’t clean up now – you need to pay attention to finishing your clay – so, cover your hands in lots of cornstarch and knead your dough.

Caution – your clay may be very hot – so check first before you plunge your hands in. But start kneading as soon as it reaches a temperature you can handle – if you leave it too long, a crust will start to form.

Dust your hands - no, smother them in cornstarch - and start to knead.

You’ll find it easily kneads into smooth consistency dough. Pull it apart to get the insides to the outside and make sure the whole dough get mixed in during kneading.

Look out for when it starts to have ‘cracks’ that don’t stick together – it’s ready at that point or when it forms a nice roundish lump of clay that doesn’t stick to you or the table.

Put it in a plastic bag and tie it.

NOTE: always keep clay you are not using in plastic sealed off from the air – this clay dries quickly and when it half dries, it is difficult to form good shapes from it, so keep it wrapped up.

Colouring The Clay

You can easily colour this clay using any water based paint - acrylic, poster, watercolour, food colouring will all work. Some oil paints will also work but they may cause it to dry very slowly or may not mix in and will exude oil so be careful and try it out on a small bit first.

NOTE: Opaque paints will make your clay more opaque, translucent paints will help keep it see-through if you want to make decorations that the light will shine through.

Whatever paint you choose, take a lump of clay, make a small well in the middle by pushing down on the clay with your fingers. Squeeze a little paint into the well and then wrap the edges of the clay over the well.

Don’t worry if paint sneaks out – as long as it doesn’t spurt out all over you, just keep pulling the clay and wrapping it over itself in any random way and the colour will mix in.

Just keep an eye out for the clay getting too wet from the paint – if so, pick up any cornstarch or drier bits of clay left on the table with the clay or if necessary, sprinkle more cornstarch onto the clay.

You’ll find it can get quite wet without becoming sticky if it is made well. And at the other end of the spectrum, don’t mix it until it starts to dry out either! You can add in more paint i.f you want a stronger colour

You can choose to mix until it’s a uniform colour or stop when it is still marbled with natural and your colour. You can marble two or three colours together also – just roll out two coils and twist them around each other, then fold and twist and roll, fold, twist and roll over and over until you get to a marble pattern you like.

When you’re done colouring, and marbling, pop the clay in a plastic bag and tie it off.

Let us know if you try this out - and if you have any questions - just pop it all in the comments box - love to hear from you.

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