Working with Paper Clay Questions

[WVerbaas]

Paper clay newbie here with a bunch of basic questions that I can't seem to find answers to online.

I just purchased Vachon White Paper Clay (cone 04-6) from Seattle Pottery Supply. I've never played with paper clay so not sure what it's supposed to feel like. This one is very firm, does not smooth very well, has stress cracks when I bend it, and doesn't seem to want to blend well.  If I use a cookie cutter on it, the paper fibres are clearly visible and need to be smoothed back in.  Is it possible it's too dry and if so, what is the best way to hydrate it? Any other tips and tricks for making the most out of working with it? Stick to sculpture? When bisque fired, will it have a rough texture? Should I consider glazing with thicker glazes to help smooth out the final texture, or will underglaze be fine?

Thanks in advance for any and all advice. Is there a good resource book that covers all of this?

[JohnnyK]

The only thing I have to say about paper clay is that I have tried using the slip for the handle joins on some mugs and in every case, the joints cracked or came completely apart when drying. Not going there anymore...

[Hulk]

Wood fiber reinforced clay, I've no experience with it, and bein' enamored with wheel throwing, I may never, however, I am curious!

Likely the fibers help transmit moisture to the surface and hence out of the clay. Perhaps, like un-fibered clay, the body can be hydrated using typical methods, e.g. cut into slabs (3/8" or so), spray both sides with water, stick them back together, wedge, and repeat until desired wetness is achieved. Be sure to wedge thoroughly.

Once bisqued, very likely the clay will be more porous, as the fibers will have burned away, hence more fragile as well.

I don't imagine paper clay would throw very well? I'd thought the purpose of adding fiber was to aid hand building/sculpting.

Links for the curious:

10 Paperclay Tips | Emma Will - YouTube
How to Use and Work With Paper Clay (thesprucecrafts.com)
Paper Clay Sculpture - A Fantastic Way to Strengthen Your Work! (ceramicartsnetwork.org)
Making Paper Clay Storage Easier and Less Stinky (ceramicartsnetwork.org)
All About Paper Clay - Spinning Pots
Overview of Paper Clay (digitalfire.com)

If one, this one:
http://www.grahamhay.com.au/paperclay.html

http://www.paperclay.co.uk

Note: the Graham Hay link may be a good place to start, "THE place for all your paper clay information"

 

[Callie Beller Diesel]

All of what you’re describing is absolutely how this material behaves, yes.

It can help to rehydrate it a bit, if you’re finding it stiff or that it’s cracking. Whatever method you prefer to use will likely work, but be advised that the paper fibre will wick the water into the clay quite rapidly. If you do the submerged bag of clay in the bucket of water method for instance, check it after about 5 minutes. You don’t want to liquify the stuff by accident.

When I was working with it in college.  we just made it out of reclaim slurry and either cotton linters from the bookstore, or super cheap 1 ply tp we “liberated” from a bathroom at school. The tp had a very short fibre and was fine if you were using it right away, or if you were making joining slip. Not much to recommend it otherwise. The linters were nicer because there was no sizing or other additives in it, so it provided a long fibre that broke down quickly and dispersed easily in the slurry. If you’re making your own, unused newsprint is a happy medium. The reason I mention this is because it’s easier to control the consistency when you make your own. Added bonus: you can dry the stuff in thin sheets and rehydrate as necessary to avoid the Rankest Stink Known to Potterykind that is rotting paper pulp.

I disagree with a couple of points from that article from the spruce crafts.com. I would not use commercial paper clay for functional work, unless you’re using some slip to join handles. Once the paper fires out, you’re left with a more porous and friable piece than the original clay body would have been by itself. This can cause issues with weeping if your glaze isn’t ironclad. They mention people can throw with it, but it is a lot more difficult. It is best left for sculptural/non functional items in my opinion. Again, if you’re making your own and control the fibre size and quantity, this might be a different scenario, but you’d have to do some porosity tests to make sure. 

As to how textured it will be, that will depend on the size of the fibre that’s used to make it, and I haven’t got any direct experience with the Vashon to speak from. It will be a matter of if there’s a texture before firing, it will be there afterwards. You won’t get a big shock when it comes out of the bisque. It’s not smooth like a thrown mug ribbed with a metal rib, but it’s not like a groggy body either. 

Will the glaze fill it in? Yes.  Will the texture show under the glaze? Depends on the glaze and how pronounced the texture is. Something translucent that breaks and pools easily might highlight it. 

Can you just finish it with underglaze? For sculptural work, give ‘er! (Yes.) Being a matte finish, it will reveal any texture though. Again, what you see is what you will get. 

 

[Piedmont Pottery]

On 12/14/2021 at 1:25 AM, JohnnyK said:

The only thing I have to say about paper clay is that I have tried using the slip for the handle joins on some mugs and in every case, the joints cracked or came completely apart when drying. Not going there anymore...

Interesting, I have had the exact opposite result with using paper clay slip to attach handles, I find that the paper clay slip attached handles are much less likely to crack at the joint than when using regular slip.  I use fairly deep scoring on both handle ends and mug, and just enough slip to fill in the scoring on both.  Slow drying is necessary in either case.  

[kswan]

I got some information about making paper clay from Jerry Bennett, a ceramicist in Pennsylvania. He works exclusively in porcelain paper clay and makes functional work. I ordered his online class for making paper clay which was helpful in understanding the material. I don't think there is a similar tutorial yet for how to use it once made. It looks like he teaches workshops too.

I've begun experimenting myself using purchased sculptural paper clay to make some 2 foot wide wall hangings. I am getting ready to bisque some of these things and crossing my fingers they don't crack. I made a smaller test piece and it came out okay.

I made my own paper clay based on his instruction, and used it for a shape that kept warping in pervious iterations. The final piece felt about as dense as a normal piece, but the unglazed bottom was definitely a different texture that my usual clay.  

It did feel weird using it, since you do see the paper fibers when you cut it, and you don't knead it the way you do regular clay. You have to cut and smoosh it together and smooth it with a rib or your finger. 

One main advantage of paper clay is dried greenware strength. I am making these big panels that would break apart if I tried to move them around without the paper in there.  I still have the piles of clay shards sitting around from a previous attempt at making large flat slabs!

[WVerbaas]

Next question! When bisque firing, when the kiln reaches the temperature at which paper burns (Farenheit 451!), will I need to deal with smoke being generated (I fire in my garage and don't have an envirovent). Does it shorten the life of my elements? Will the final pieces be the same strength as regular clay?  I am hoping for more, as when people make a bouquet of my flowers and they bump into each other, they often break - don't like unhappy customers! Can any sculptural work live outside without cracking, and if so, in what kinds of weather/conditions? Thanks again!

[Mark C.]

I have had good results with paper clay when I needed it. Its a pain to cut. If you need strength (your attachments to stay and not slump this is the stuff.

I made a series of salt fired kiln gargoyle for out fence posts.

The arms where slumping and paper clat fixed that-same with the ears.

I had no troubles with scored and slip attachments but did cover and slow dried them as you would with any sculpture /throwen work

I also used some paper supports as they are forgiving as clay shrinks. These are stoneware and porcelain -body is throwen cylinder they have tails

Here is one they about a foot tall or more

 

 

 

[kswan]

The paper won't make much more smoke than wax would. You could leave the top peep open until it finishes smoking and open a window or door in your garage to air it out. I have a kiln vent and my kiln wasn't full of the paper clay, only some pieces were made of it, but I didn't have any smoke at all. It shouldn't harm your elements but maybe slow down the firing while it is still burning off.

Paper clay doesn't end up any stronger than regular clay, since it totally burns away. It's just the plain clay body. If you have trouble with things breaking by bumping each other, use a stronger clay like a sculpture clay with grog and/or sand. Also, make your pieces thicker, it sounds like they are really delicate.

I've made planters and bird baths from my regular stoneware clay and it has been going strong for years. I think there are specific sculpture clays meant for outdoors but I haven't used them. Just don't use a porous clay like earthenware because it will crack and fall apart when it's out over the winter.

[Callie Beller Diesel]

Outdoor items are subject to the freeze thaw cycle, so whatever clay you use for that has to be as vitreous as you can get it, and not have places where water can pool. If pooled water freezes and thaws, the same thing happens when you put a Mason jar full of water in the freezer.

I made myself a few planters that lasted about10 years outdoors until I let water gather inside them. They didn’t spall like the cheap terra cotta things from Canadian Tire did, it just cracked all the way through the middle.

[Min]

On 12/17/2021 at 6:06 PM, WVerbaas said:

Can any sculptural work live outside without cracking, and if so, in what kinds of weather/conditions? Thanks again!

@WVerbaas, read through this article.  In a nutshell if the clay is porous it needs to have an open pore structure so as the water expands as it freezes it has minute tunnels or capillaries to expand into. Article covers dry weight vs wet weight vs boiled weight and the saturation coefficient industry uses for freeze / thaw cycles. Link to how to do the soaked and boiled tests here.

[Mark C.]

My clay dogs are high fired in a slat kiln and live outdoors-niot super freezing here but occasionally  it does freeze -they are fine outside.

Not enough paper to worry about in a kiln load for smoke .

[KachemakKaren]

I used cone 6 Grolleg paper clay to make poppies for the garden.  They've been outside for several years exposed to sun, rain, ice and snow with no problem. It's a surprisingly strong material.  (hoping to attach a photo)

[WVerbaas]

Beautiful! So, is porcelain paperclay stronger than "regular stoneware paperclay"? Just looking for something that can take a bit of bumping (like, from my husband's briefcase when he barges in the door past my planter full of lovely flowers).

[Callie Beller Diesel]

The porcelain will hold up better because the finished result is vitreous, and probably not porous in any significant way. Paper fibre adds strength and flexibility to the piece while it’s being formed, and allows you to get shapes that might otherwise be difficult to build. Once the paper burns away in the bisque, you’re left with whatever clay body you added the paper to, with whatever properties it has when fired to maturity. 

If you’re looking to make an outdoor flower display, the best you can do is make sure you fire the clay to maturity. If you start with a stoneware or a porcelain that’s suitable for food use under normal circumstances and don’t add too much paper fibre to it, you’ll get the best results for the circumstances you describe. 

I called Seattle Pottery Supply to ask about the porosity numbers, shrinkage and percentage of pulp in the Vashon paper clay. The guy I talked to was pretty nice, but he said they’re in the process of getting those numbers up on the website and he didn’t have them to hand. My suggestion would be to make a test bar and find out what the porosity will be in the finished product. You’d want to do this under your firing conditions anyways.

I did a little more poking around on Digitalfire, because I was trying to find the article that outlined how to do a porosity test. Found one better: a discussion on making outdoor suitable work. The porosity test is also in there, so here’s the link. Plainsman clays are formulated by Tony Hansen, who wrote Digitalfire, but were produced for years by XL Brick, so there’s some authority there. Medalta took over the pottery clay production a few years ago, but I digress.

A couple of notable points from this article: they recommend against using non-porous white bodies mostly because of potential issues with construction stresses and warping in the kiln. They’re discussing large scale mural projects though, not relatively small individual pieces like you describe. Also, the paper will prevent a bunch of the construction issues they’re worried about.

They also mention possibly using things like paver stone sealants to hedge your bets, which made me smack my forehead for trying to overthink it too hard.