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Can we use powdered drywall joint compound instead of the pre-mixed kind that the Silky-Smooth Air Dry Clay recipe calls for? Our friend Karima Rebecca Powell did an experiment to find out. Read on to see what she discovered…
BTW – her instructions for mixing the powdered joint compound should work just as well in the original Paper Mache Clay recipe, too. 🙂
©2021 Karima Rebecca Powell
Making Paper Mache Clay with Powdered Drywall Joint Compound
I was super delighted to come across Jonni’s site ultimatepapermache.com and her tried and tested amazing resource recipes for paper clay.
After reading and rereading and looking at the comments, I decided to try my hand at some test runs using the Polyfilla dry powder and ready-made paste to see how they performed, how they felt, smelt, dried and the differences.
First the colour, Polyfilla dry powder is grey whereas the readymade paste in a tube is more ivory in colour. No difference in smell to the resulting clay.
I made the recipe according to the one on the website. I made half with the ready made multi purpose Polyfilla and half with the powdered one.
The mixed air dry clay. The darker versions are the ones made with the powdered drywall joint compound, the lighter ones are made with pre-mixed joint compound.
Mixing the powdered joint compound:
The dry powder needs to have water added to it 1 part water to 2 parts powder, mixed to a smooth paste and used as soon as possible in the recipe. I left some in a ziplock bag and it was rock solid in a few hours and no way to use it.
You will need to mix 67 ml of water to 133 gms of powder to get 200 grms of paste to add to the recipe as on the website. (67 +133 = 200) with this ratio you can halve or double etc as required. It may be easier to measure 75 of water and 150 of powder and sacrifice the 25 gms left over if it is fiddly to get the exact liquid measurement.
The price is a big factor too, the ready-made being anything up to 3 times the price or more for the same weight of powdered.
Once the clay was made up, it required kneading much like bread, until it is smooth using the cornflour /cornstarch. Being made with paper pulp, it will remain slightly fibrous, yet smooth.
The powder one turned out a bit heavier than the readymade one, the readymade one a bit smoother than the powder one, these variants could have been due to the amount of cornflour used when kneading the clay.
Sculpting and moulding the two versions of air dry clay:
On the day it was made, it was put into some small silicone moulds and the following day removed. The powdered clay pieces had dried with a nicer finish, very clean and smooth. I placed the clay in ziplock bags in the fridge.
I also made some paper mache clay with the powdered polyfilla the same day using Jonni’s recipe and put it in the fridge. After a week it still looked and smelt perfect, but some of the water had seeped out so it will need kneading again to incorporate the water back in.
During the week I made small clay shapes with the readymade clay and I was very pleased with the texture, how thin I could get it and how light they were when dry.
The powder clay one was not quite as smooth. So one was better for moulds and the other for sculpting. I think perhaps at the mixing stage, I could have done it for longer to bind all the ingredients and break up the fibres more. Next time I will see if that makes any difference.
After a full week I took the two clay samples out of the fridge. They both smelt the same and no problems. The powder made one was softer than the ready-made clay one which surprised me.
So just to recap… to make 200 grms of polyfilla paste: 1 part water to 2 parts powder.
- 75 ml water to 150gms powder makes 225 grms paste.
- 67ml water to 133 gms powder makes 200 grms paste.
Easiest way is to take the final required amount…ie: 200 and divide it by 3. Gives 66.66 and times that by 2 gives 133.33 and round it.
Polyfilla is the product available to us in Ireland and the Uk, it may be known in other countries as joint compound or drywall filler or joint filler. Check on the packaging how much water to add to the powder.