Paperclay and regular clay for raku

[Terri98]

I work with a stoneware body for Raku.  I use a cone 10 body and sometimes a cone 5 body.  I add kyanite and grog.  Generally, I am hand building as opposed to slab building.  I like what I read about paper clay.  I see people dipping, pouring. slab building but not sure if it fits my approach.  I also like to use texture, and sometimes  fine detail.  

I like that paper adds strength.  What about plasticity?  I like that it can be used to patch cracks and possibly help mend breaks even on bisque ware.  Really? 

If I had a paper clay made from the same clay I raku with would it be possible to use that on green ware cracks prior to firing?  After first firing?  That alone would make it very interesting.

If both clay bodies share a parent body could I mix the two?  Knead them together?

Is there a paper clay designed for raku?

I was reading some of the articles with Jerry Bennett, he mentioned a fiber that is sometimes used with Raku, can not quiet remember what he called it.  I looked it up online might be in the hemp family.  Not sure. 

Very intrigued just not sure how to approach it.  

I can see how it would be beneficial for wall pieces. Less weight.  

I would appreciate feedback and insight on what might be possible.

Thanks

Terri

 

 

 

 

[Callie Beller Diesel]

Paper pulp added to clay definitely adds green strength, and makes attaching a lot easier. It’s best used while the piece is still within the  normal working ranges of clay, but you can patch or repair bone dry or even bisqued pieces with some caveats. The clay body the pulp is mixed with may still be subject to some cosmetic hairline cracking if it shrinks a lot, eg porcelain. Any repairs are still subject to bad engineering. For instance reattaching 2 broken bisque pieces by smearing the surface with slip will still be a structurally weak bandaid to start with.  After the paper fibre burns out, you’re left with a slightly more friable version of the clay body you made the repair with. If you only need a cosmetic repair it’s fine, but not something to use where you need structural integrity.

 

You can make paper clay out of any commercial clay body by simply adding wet paper pulp to slurry in the amount desired. No, there are not specific recipes. I got taught to steal the tp from the bathrooms at college (it was the *finest* institutional single ply available), soak it in water and blend it up with a paint mixing bit. Wring out most of the water from the pulp, add no more than 20% by eyeball to a bucket of reclaim and mix thoroughly before drying.  I have added paper pulp to raku clay using this method, and it worked great for sculpting. You can get more refined with your clay and pulp choices if you want. I had access to cotton linters for paper making, and I found I preferred the longer fibre, but it wasn’t strictly necessary.

Re: Wedging paper pulp into pre-prepared clay: that’s going to be a non-starter. It won’t distribute evenly, and you’ll be there for days trying to make it happen. Even cut and slam doesn’t get you that far. If you’re making your own, you do need to make it via a slurry method and dry it out to your desired consistency. We used to pour a thin layer of slurry out on a plaster slab, and it’d be ready to use in an hour or 2.  You can either use the thin slabs since they’re handy at that point, or you can use it in the hand building method of your choice. 

As always with paper clay, it’s a good idea to add some of your favourite bacterial growth inhibitor, and either use the batch quickly, or dry it out in thin sheets and rewet when you want to work with it. The pulp begins to rot within the week, depending on how wet you’re keeping it. In addition to smelling like something died, the fibre gets less strong as it decays. 

[Terri98]

Thank Callie. 

 

Very helpful info. 

What type of bacterial growth inhibitor might I use?  

I had heard that it can be rolled out and dried and re-wetted and it bounces back to life.  That sounds so crazy to me.       Can not imagine that with traditional clay.

[Denice]

I have made paper clay  several times,  I have never found anything that was very good at inhibiting mold growth.   My home made paper clay was good for large sculptural pieces but not good for fine detail work.  My local ceramic store started carrying paper clay,  I bought 100 lbs of it and loved it.   It was more like regular clay and much easier to work with.  I had about 5lbs of clay left when I was finished with my project,  I rolled it into a slab an let it  dry.   When I need to repair a crack or reattached something I will break off a piece of paper clay.   I soak it and then add it to the clay I am working with.  I didn't have any problems with the clay growing mold.   Denice

[Callie Beller Diesel]

You can stave off some bacterial growth with bleach, but it’s hard on the hands. I’ve seen others recommend things like Dettol, but it really is best to make up what you need, use it within a week or 2, or store very thin bone dry sheets that you re-wet. When I was working with it, there were no commercially available paper clays, so I have no idea what manufacturers use as an antibacterial agent.

The re-wetting thing is indeed very cool to observe and play with! It gives you a lot of flexible ways to work. 

[PeterH]

1 hour ago, Callie Beller Diesel said:

When I was working with it, there were no commercially available paper clays, so I have no idea what manufacturers use as an antibacterial agent.

Don't some/many commercial "paper" clays use flax fibres, which I assume don't rot.

My experience with paper clay was also long time ago. Non-paper fibres were available but IIRC the minimal order was both expensive and very bulky -- while cheap toilet paper was readily available everywhere.

PS Another option to prevent rot, keep the paper clay dry.

Also see the next post in that thread, which recommends copper carbonate. Which I believe  is sometimes used as a disinfectant in in glazes.

[Bill Kielb]

On 10/30/2022 at 11:54 PM, Terri98 said:

I like that paper adds strength.

Maybe early strength and workability. When the fibers burn away it will likely be less dense so also likely the same or less fired strength.

 

21 hours ago, Terri98 said:

What type of bacterial growth inhibitor might I use?

Have not seen it mentioned above but peroxide can be useful, a bit less harsh than chlorine and ends up as plain old water.

[Hulk]

Hydrogen peroxide
 "...most common peroxide is hydrogen peroxide (H2O2), colloquially known simply as 'peroxide'."

[Kelly in AK]

Anything organic in the clay is going to rot sooner or later. Balancing the strength of antibacterial agents against their negative consequences is one way, but drying the clay in thin sheets to use as needed seems like a good solution to avoid that issue altogether. Paper clay has unique and very useful properties, to be sure.

The amount of fiber in the clay is an important variable as to how it behaves. If you come at it from the direction of how much clay you have to add to make paper pulp sculpt-able and fire-able you’ll get one material, or, from the direction of “how little pulp can I add to make this clay more plastic and forgiving,” you’ll get another. The term paper clay can mean different things to different people. For fun I once made a clay that was more paper than clay, with a liberal amount of Veegum to plasticize it. Made a couple pinch pots and tiles, then fired them. Very lightweight stuff, a fascinating ceramic detour. 

The most common useful formulas for handmade ceramics suggest <20% by volume paper, mixed in slurry form, as @Callie Beller Diesel mentioned. I usually have some on hand for students attempting “emergency repairs.” Because it’s mostly used for repairs, I also add a little soda ash (around 1-2%). Of course students always get a lecture first about why the crack happened in the first place. 

[Min]

On 10/28/2023 at 2:42 PM, PeterH said:

Don't some/many commercial "paper" clays use flax fibres, which I assume don't rot.

I think the flax “paper clay” is from your side of the pond Peter. I have a friend who went to a workshop in England a number of years ago who made a flax paper clay pot, couldn’t find any suppliers of it over on this side of the pond when we looked for it.   I wonder why it never has become a thing over here? Cost maybe? I know some handmade paper supply places carry flax fibres, it would be a good experiment to see how flax vs paper clay compared in regards to rotting.

[Callie Beller Diesel]

The flax fibre may just be an availability thing. I used cotton linters because they were stocked in the bookstore for a paper making class, they were relatively cheap, and while they were considered short for papermaking, they were a long fibre for paper clay.  I can’t remember if flax was available or not, but I remember discarding a number of other available plant fibres because they were too long for the purpose, more costly or both.

Lots of folks will fine tune a material if they use it extensively and develop preferences, but for repairs, starting out or occasional projects, using old newsprint or tp really does work a treat.