Making Paper Clay Storage Easier and Less Stinky

cutting-paper-clay-695

Paper clay is an ideal solution for building complex or delicate ceramic sculpture. Made by mixing any type of clay body–earthenware, stoneware, raku or porcelain–with paper pulp, paper clay improves joining capabilities and decreases warping and shrinkage, all the while reducing the heft of the work.

But when it sits around, it can get rather stinky. In this post, Diane Gee explains her solution for avoiding the stink and making paper clay easy and convenient to store. – Jennifer Poellot Harnetty, editor.


A Brilliant Tip for Storing and Using Paper Clay

by Diane Gee

There are several advantages to drying and storing slabs of paper clay, including saving space; avoiding the rotten, moldy smell of wet paper clay as it ages; and the fact that when reconstituted, it’s easy to roll, drape, cut, or form in a multitude of ways. The biggest advantage to making dried paper clay slabs is the time savings. It’s easy to make, and when you need to reconstitute the paper clay, just break up the slabs into smaller pieces, add water to the desired consistency, and you’re quickly resupplied.


Break all the rules!

In the world of contemporary ceramics, rules are meant to be broken! Additions to Clay Bodies is an introduction to a group of artists who break the rules by mixing just about anything into their clay bodies—from hard materials like stones and glass to dog biscuits, coffee beans, fiber, and metals. If you’re tired of playing by the rules, this book will send you off in a refreshingly new direction!


paper-clay-2

Paper clay slip can be made from a recipe (see below) or by slaking down the clay body you already use, adding 5–15% paper pulp to the slurry, and mixing it thoroughly with a drill mixer. After making a fresh batch of paper clay slip, pour a generous amount onto a bisque or plaster mold. Use a rib to spread the clay out evenly on the form. It should be at least half an inch thick. It may take several consecutive pours to get the desired thickness. Note that the slip will shrink dramatically as it dries, and if your slabs are too thin they may curl while drying and may chip when you store them. Leave the paper clay slabs on the plaster until they are completely dry. You may need to flip the slab over on the plaster to keep it from warping. This makes for easier storage.

paper-clay-4

To reconstitute a paper clay slab, use a spray bottle to evenly wet the top of the slab. It usually takes 4–6 thorough spray soakings to fully reconstitute the dry slab. This gives you a lot of control over the degree of wetness. For faster results, put the slab on a flat board with water. Be careful with the latter method; if you’re not paying attention, the slab can quickly revert to mush (in which case it is best to dry out the mush once again on the plaster slab. One obvious way to tell when your dry slab is ready, is that any curl or warp in the slab will disappear, and the slab will relax and lay flat. Once that happens, you can use the slab any way you want. Another great aspect to making paper clay slabs is that you can cut them with scissors or a utility knife. The slightly reclaimed slabs can be cut into specific shapes (dry slabs can be drawn on with a pencil, and the marks will remain even after the spraying). When they are damp and slightly pliable, the slabs have a very fabric-like feel and capability that increases if they are rolled out even thinner with a rolling pin or smoothed with a rib. Fabric techniques such as darting, gathering, draping, and ruffling are all possible with care and practice.


Comments
  • John R.

    I love it. The mold, bacteria, etc which all conspire to make aging paper clay grotty just won’t happen w/ dried slabs made up while the material is still new. And I like that dried slabs are light and easy on the back compared to a bucket of several gallons of this exciting material. Well done.

  • Jill N.

    I have found that it is the ingredients in the paper that make for the stink.
    I understand that toilet paper is coated with cornstarch to make it soft and fluffy. The fermenting cornstarch is what causes that awful pong! I use only shredded office copy paper (free from our local medical centre).I have buckets of soaking paper which must be at least two years old and provided I seal the lid carefully there is almost no smell and what there is, is not unpleasant.I found a problem with storing dried slab paper clay in that it needs to be labelled and each type of clay kept separate as, while it will be fine to combine pieces in a form, when it is fired of course the various clays are patchy and take glaze differently.Your storage unit also needs to be absolutely dust free.

  • Eric W.

    To avoid the mold and stink of “paper clay”, a few items from my own fiber clay experience.

    1. I don’t use toilet paper. It isn’t just plain paper fiber. It has a lot of binders and fillers. Often the binder is cornstarch or similar, which feeds mold growth so it develops even faster. Other fillers can be inorganic stuff that’ll cause some nasty fumes when firing.
    When I used paper, I soaked newspaper until it broke down into pulp. (Just the newsprint pages, not any glossy inserts, etc.) It does makes the resulting wet clay gray from the ink, but newspaper ink is soy-based and will burn out in bisque and not effect your end result. The only concern is if you are sensitive to newspaper inks, handling the clay could cause you problems.

    2. Add a little bleach to the slurry. Not much. I’d use just a couple tablespoons in a 25 pound batch. It shocks the batch, killing any active mold spores. It won’t stop the paper fiber in the clay from eventually molding from new spores that get to it, but it can delay the rotting process. Once more, if you are very sensitive to bleach, even in this tiny ratio amount, it could be a concern for you.

    3. I actually don’t use paper any more. I use cotton fiber. “Cotton linters”, available from many craft/hobby shops that carry paper making supplies, or found online. The cotton linters is about the same consistency of paper fibers and behave the same in clay as the paper fiber. The big plus with cotton is it doesn’t rot as easily as the wood cellulose in paper. It’s why “paper” money is made with cotton and not actual paper. I do still do the bleach step, but even when I forget it, I have yet to have a batch of cotton fiber clay go moldy on me.

    As an example, I had forgotten a partial bag of cotton fiber porcelain in my garage for almost a year. We went through a very turbulent winter with a lot of freezes and thaws, then through a long, hot summer. When I found the bag in the fall, the lump of clay (around 12 lbs of it) was a bit stiff but still wet. From the outside it looked white and clean, my first surprise, but who knew what alien life form has grown inside. I opened it up and sniffed. It smelled like fresh laundry from the wet cotton. I broke it open and it was creamy white all the way through. Later in the studio, I sliced it up into small slabs, sprayed them, and let them reconstitute to a workable consistency. The clay handled no differently than a fresh batch, and the resulting pieces were no different than any other. Since then, I have had other batches of fiber clay made from cotton linters that have been stored fully wet for long periods, but better controlled conditions, and the clay straight from the container to the work table was clean, fresh, and mold-free. (And different clay bodies, too, so not just a porcelain phenomenon.)

    I do have to give a hat-tip to Jerry Bennett (jerrybennett.net, and paperclay.blogspot.com). My first experience with pottery was a beginners handbuilding class with Jerry in 2004, where he introduced me to the world of “paper clay”. Later, through Jerry, I came to know the wonders of cotton linters after he had switched over. Check out his website and blog to see some examples of how far you can actually push the medium.

  • Eric W.

    PS – sorry for the hard readability of my long post above. i had breaks and paragraphs. I didn’t realize it’d all get squashed together like that.

  • Cheryl W.

    Drying the slabs was suggested by both Graham Hay and Rosette Gault in an excellent Potter’s Council workshop on Paper Clay in Seattle a few years ago. It’s a wonderful space-saving (and health saving) way to store paper clay. The slabs can be broken into pieces on an as-needed basis, reconstituted into slurry state , then quickly worked back into clay consistency on plaster batt. Another suggestion they made: if leaving the material in the wet state, to avoid the use of bleach, use a bit of liquid dishwashing detergent, such as Dawn. I find it works equally well with less of the problems of using bleach.

  • Angela D.

    I love using paper clay and discovered adding a very small amount of copper carb to the slurry inhibits bacterial growth and the copper does not degrade like bleach will. I add a heaping teaspoon to 5 gal bucket of slurry or 1/4 teas to a pint of slip. This small amount of copper will not show any color in the clay.

  • Has anyone tried using lint from a clothes dryer screen? Seems like this would be a free source of fiber and creative way to recycle something that otherwise goes into a landfill?

  • When I make paper clay I use ordinary toilet rolls soaked down with water to which I add a little anti-bacterial household cleaner, the stuff that comes in spray bottles to clean your work surfaces. That seems to do the trick.
    I do acrylic paintings too and I always use some anti-bacterial cleaner added to the water in the staywet palette. Keeps it all smelling fresh.

    Sorry I dont have any measurements, I just splash it in!
    Cheers
    Joy

  • Dr. David S.

    This article and the discussion are very timely for me. i recently started to use commercially prepared paper clay in an effort to make my pottery thinner and lighter. I formerly used porcelain but found that medium difficult to use for hand building very thin pottery. Porcelain lacked the body that paper clay affords me. After several months my paper clay is turning moldy and starting to smell. I appreciate the ideas expressed in this discussion and plan to now cut my paper clay into slabs for storage.

  • @Howard Frank – Unless you’re certain the lint is from 100% natural fibers (cotton, linen, rayon, etc.), I wouldn’t. The rest is probably polyester, nylon, and other things you wouldn’t wan to be burning in the kiln. Also, materials like paper fiber and cotton linters are cut fibers, so are intentionally short. Clothing fibers are longer to give thread strength. It may make a difference in the handling of the clay.
    If you want to use the lint, put it in a net bag (like what oranges and other fruit can come in), and hang it out for the birds to fluff their nests and keep the babies warm.

  • I was wondering if you could add sodium bisulfate (what winemakers use to kill molds and bacteria) before storing the paper clay.

  • Sue M.

    Thanks for the tip on “cotton linters”.

    I forget where I saw it, but someone suggested putting a few drops of clove oil into the mix. It has antibacterial properties, and so far it works like a charm.

  • Michelle M.

    I make stoneware paper clay (cone 8) using toilet roll but I’ve found its best to use a high quality quilted 3-ply toilet paper and not the cheapest stuff! I also add the pure essential oil Tea Tree to the paper pulp and I get 6 months or longer from my paper clay. I’ve seen batches last a year! I add about 1 ml (20 drops) of pure Tea Tree for every roll of toilet roll used. I also add it to my paper clay joining slip and it works the same. I’ve tried all the other additives and for me this works best. FYI I live in a damp, mild climate – Ireland – its doesn’t get hot here very often : )

  • Janie V.

    I use vinegar to make my paper clay slip, and have never had it get stinky or moldy. Would vinegar not work in making the paper clay itself? I just use cheap toilet paper and stoneware clay. Vinegar is cheap.

  • Thomas K.

    The best solution to avoid paperclay rot is to use cellulose insulation as your paper. It is allready treated for mold resistance. I love it.

  • Diane G.

    Essential oils are a great option, but I’d strongly suggest Tea Tree over Clove Oil … Clove is not only a ‘sensitizer,’ it can be a ‘cross-sensitizer’ … that means, over time, you can develop an allergic-like sensitivity not only to the Clove oil, but also to other closely related Essential Oils. You should avoid getting it directly on your skin, and use in extremely low dilutions (1-2%)

    Tea Tree, on the other hand, is broadly antiseptic (anti-bacterial, anti-viral, anti-fungal, and anti-parasitic), and extremely safe to use, even directly on the skin. I only use Australian sourced Tea Tree, as it is carefully monitored for quality. (Trivia: It was a staple in Aussie WW II Medical Kits as an antiseptic, when commercial products were unavailable.)

    (FYI, I studied Essential Oils for 5 years before I retired from my first career, and expected to have a Botanical Spa product business as a second career … but clay came back into my life, and it won. I still ‘dabble,’ but a family friend has taken over producing small artisan-crafted batches of my a’Scent formulas.)

  • I’d like to make paperclay just from ball or china clay in its powder form plus the cellulose source too. Can anybody tell me if thats possible? Have they done it themselves? Or do I have to use perlite as well?

  • Helen H.

    About using cellulose insulation in your paper clay: Isn’t it treated with fire retardant? Would that be an issue in the kiln?

  • Subscriber T.

    I actually like the idea of using cellulose insulation, it’s cheap and pre-pulped. Yes, it has a fire retardant, boric acid (borate). This won’t burn out but might change the firing characteristics of the clay body.

  • Thomas K.

    There are borates in the cellulose insulation as a fire retarder. Borate is a flux in ceramics. It could affect firing temperature. I use it and it doesn’t smell but gets dark stored as wet wedged clay. I did not originate this use but I would not make use of anything else.

    • Ericka N.

      that is true that the fiber clay from New Mexico clay does not rot but it is not really paper clay and behaves differently

  • As a wine maker I can tell you that the Sulfites (not sulphates) added to wine rapidly degrade and make Sulpher DiOxide gases. It is the SO2 that kills the mold, bacteria, and wild yeast. But it also smells bad. So if bad smells is what you are trying to avoid, this might not be your best bet.

    There are many other food preservatives available that inhibit bacterial growth, tho I don’t know what they release when burned…

  • Donna K.

    I made up a test batch using a slip recipe for the clay. It vitrified in the bisque firing ^04 (pretty, shiny body that stuck to the other tests). Someone else tried it with just our regular clay (SS240 I think) and it was fine. Oddly though the pieces that were vitrified in the bisque did not slump in a ^6 firing.

  • Gaynell M.

    Does anyone have suggestions for bringing moldy and dried out blocks of commercial paper clay back yo life? Or should I more safely give it a proper and honorable burial in the worlds?

  • Cynthia B.

    I use a community kiln that fires earthen ware to 06-04 only. If I want to fire paper clay made with earthen ware, will it affect the earthenware sharing the kiln? I was told it needs special venting and is disruptive. Is this true?

  • Can I ask pick some brains please. I’ve been researching cotton linters for use in paper clay to avoid my sevete mold allergy.

    Does anybody know if a cotton linters is the same as cotton fibre because I bought cotton fibre for felting. Can I use that?

  • Ericka N.

    Please be careful when adding chemicals to your work. Please look at MSD sheets to find out if you could be harming yourself.

  • Chris H.

    Bleach, smelly; metabisulphite, smelly and releases SO2 (potentially dangerous) on firing; tea tree oil – don’t know, but sounds pricey.
    Try 0.5% copper carbonate: copper is very good at stopping mold, is usually available in a potter’s studio, and at that concentration there is no noticeable colour from it. I use it, and the paper clay doesn’t rot at all.

  • Catherine G.

    Best and safest solution to restore old stinky (even moldy) paper clay is hydrogen peroxide, just the regular cheap kind. Pour some in the bag, smush it all around to wet all the yucky spots, tie up and in a couple days it will be just fine. Just be careful to wear a mask when opening bags of moldy clay so you do not inhale spores.

Leave a Reply

You must be logged in to post a comment.

Enter Your Log In Credentials
This setting should only be used on your home or work computer.

Larger version of the image

Send this to a friend