Using Powdered Drywall Joint Compound for Air Dry Clay

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.

ready made and dry polyfilla
ready made and dry polyfilla
2 clays
the 2 clays
the two clays
showing the 2 clays

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.

filling the moulds with the dry powder clay
filling the moulds with the dry powder clay
removing the powder clay from the mould
removing the powder clay from the mould
dry powder clay in the mould
dry powder clay in the mould

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.

dry powder polyfilla clay
dry powder polyfilla clay
ready made polyfilla clay
ready made polyfilla clay
extruding the dry powder clay
extruding the dry powder clay
extruding the clay with ready made polyfilla
extruding the clay with ready made polyfilla
extruding
extruding
showing the thinness of the two clays
showing the thinness of the two clays
sculpted and moulded pieces
sculpted and moulded pieces
moulded and sculptured pieces
moulded and sculptured pieces

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.

Rebecca.

www.linktr.ee/rebpowell

17 thoughts on “Using Powdered Drywall Joint Compound for Air Dry Clay”

  1. Well done Rebecca! Thanks for taking the time to do this experiment and sharing it with us! It was a thorough and well thought out tutorial!

    Reply
  2. Wonderful! How did you get the undersides of the shells hollowed out? Your finished ones aren’t flat on the undersides like they are in the molds.
    Enquiring minds… Makes them look a lot more real!

    Thanks again for sharing. You do amazing work!

    Reply
    • Hi Melody, thanks for your comment.
      I think it’s partially a trick of the light as they are pretty flat, however, just by adding less clay and pushing it well in you can omit the centre part to make a dip.

      Reply
  3. Wow, Jonni and Rebecca! Thank you for sharing all your details, I really appreciate the effort you took for this post!

    Reply
  4. Thank you for your Experiment . It was very informative. Thank you jonni for this web site. I have been reading this site for a while trying to get the courage up to try my first project. I do have a question for all of you. Can you use color pigment in the air dry clay recipe? What about adding a thin layer of glue to the dry pieces to add glitter to them? Thank you all for your time and understanding of a newbie.

    Reply
    • Hi Joyce. You can add pigments, but the color will be very light because of the whiteness of the joint compound. You can add glitter, but I don’t know what type of glue people would recommend, because I haven’t tried that. I hope someone has some good advice for you. 🙂

      Reply
    • I think you could add a thin layer of the Elmer’s white glue you use in the paste to add glitter on top. I use Elmer’s white glue to add glitter in other applications. Since it is a component here, I think it would work. I’m make sure the clay was completely dry first though…you don’t want to make a barrier to letting the moisture out, it could mold easier if it stays wet too long. Blessings!

      Reply
  5. Thank you so much for all your hard research. This is a wealth of information. I live in Greece and keep wondering what joint compound is called here. Here we don’t have drywall walls, just cement but by chance the other day I came across an online hardware shop (we’re still in lockdown so nothings open) and they had bags of dry. I had no idea that dry was even available. I’m so excited to start experimenting with paper clay in hopes that I will be good enough at it to make my Christmas presents for next Christmas. Thanks again.

    Reply
  6. I loved your very thorough detective work and photos of samples. I built a large form for pouring concrete planter molds and have been wondering how to embellish the outside with a sculptured motif. You’ve given me some ideas. Loved all that you shared. Jonni’s website is wonderful. Anne Lakey. Arizona U.S.

    Reply
  7. Thank you for sharing your (Ms. Powell) tests. I love to see this kind of thing because it renews curiosity and perspective. I never have seen paper clay extruded, and though I have seen molds used with other clays, it is inspiring to try this combination. Your little pinch pot and shells are both organic and adorable. Do you take the clay out of the mold wet or dry? (Thanks, again.)

    Reply

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