View Full Version : Self hardening clay

06-18-2001, 04:40 PM
Is anyone familiar with self-hardening clay? It's supposed to become super-hard without firing. I tried working with some the other day, but when my project began to dry, it cracked. Also, I got some of the dried clay wet (purposely) to see if the project would disintegrate and it did!!! I'm wondering if painting or glazing the finished product would keep that from happening or if I should just break down and use clay that needs to be fired. Any input?


PS--please excuse me if my questions are ignorant. I'm an oil painter who has decided to try her hand at sculpture.

06-27-2001, 03:26 PM
i have never actually used the self hardning clay never really wanted to.But i have used a green colored clay that is very hard to work with that way it wont fall apart.but once you start working with it,it becomes softer but when you are done and let it set it gets hard again.you should try it:)

06-27-2001, 11:01 PM
I've been very disappointed with all of the self-hardening clays I've tried. I had been trying to use them for my fossil slab sculptures...

But, I've recently begun using Winterstone, which is basically a souped-up cement mix for artists. Take a look at my old post about it:

It really does dry rock hard (of course! It's cement!) and the pieces I left submerged in water for a few weeks seem OK. I'd still rather seal them thoroughly with a regular concrete sealant though, just in case... and, don't use it to make any food or beverage containers, needless to say. *gulp*

-=- Jen "Fossilizing" de la Cruz

06-28-2001, 10:41 AM
Ooo! I've got to get some of that Winterstone! I checked out their website and it sounds fabulous. Thanks! :clap:

07-08-2001, 02:38 PM
Post again after you try it, let us know how it works out for you?
I buy all my Winterstone from http://www.sculpt.com since they're based in New York. There's not a lot of distributors for the stuff (probably because it's not quiiiite safe enough to sell in a regular art store... I mean, cement is pretty safe, but the dust isn't great and it's basic enough to sizzle your hands if you have sensitive skin.)

-=- Jen "I just ordered more myself, whee!" de la Cruz

07-12-2001, 06:11 AM
Hi everyone
this is my first post it and I am in dire straits as to how to use this medium called air drying clay. I am in Australia and my friend Wendee and I are experimenting this medium. I have been reading the posts and some say it crumbles and breaks up. Many questions have arisen.
1. could you wrap you unfinished clay and sculpture in a damp or wet cloth and engulf it in clingwrap to be able to continue it the next day?.
2. do you have to do a mesh underlay or can you build up the clay ???
3. when completed, do u glaze or put a protective coating of some kind to preserve your work...

as you can see I need some help in this area.

this is a great site and wendee and I have spent many a happy hour or more here.
thanks for your imput

sharon aka falcon

07-14-2001, 01:40 AM
I have found that the air dry clay is hard to keep from breaking.
I suggest that you try home oven baked clay or firing clay.. nothing can really replace the results of clay that comes from our greatest natural source our earth.. and if you like to built large pieces dont' use porcelin... you will have to really grout it up to hold weight.. try your red clays and greys. Good luck!

07-14-2001, 12:57 PM
I have to agree with Roxanne on this one... air dry clay is definitely NOT an ideal medium!
That said though, you seem pretty intent on using it...
Originally posted by falcon
1. could you wrap you unfinished clay and sculpture in a damp or wet cloth and engulf it in clingwrap to be able to continue it the next day?.

This may work, but test first to see if your particular brand of clay will behave. I'd say don't use the damp cloth, since that might mess up whatever surface detail you had -- instead, just spray it with water and then cling wrap it thoroughly. You can use a sprayer as you work to keep it moist, too... but, sprayed clay will never be as malleable as fresh-from-the-bag clay. It just leaves the surface somewhat workable.

2. do you have to do a mesh underlay or can you build up the clay ???

I haven't made any really complex shapes with air dry clay, but... I bet if you just build up the clay it'll be MUCH more prone to cracking as it dries. I've been sticking with half inch thick forms with no mesh, and they haven't cracked. But I mean, if you're trying to make anything complicated, a wire/mesh armature is absolutely necessary since air-dry clay is so brittle.

3. when completed, do u glaze or put a protective coating of some kind to preserve your work...

I've tried several different glazes... Only use them once the piece is TOTALLY dry all the way through. Also keep in mind this will only protect from moisture -- air dried clay is still extremely brittle and any fine details are quite likely to fall off, chip off, etc.

1) Acrylic or water-based concrete or tile sealer (worked OK, mostly matte finish. But, it soaks in and if you aren't careful, it'll start to re-moisten your surface and take off surface detail...)

2) Spray lacquer (worked OK but I think it's more likely to crackle over time, result was a shiny gloss surface)

Hope this helps! Next time, try using something like Winterstone or a fired clay. :) Personally I would find it unnecessarily frustrating to invest a lot of effort into making an air-dried clay piece that's doomed to have such low durability, when other similar mediums work better.

-=- Jen "Winterstone fanatic" de la Cruz

P.S.: Thanks to Sandrafletcher for pointing me back at this thread.

07-16-2001, 04:13 AM
:clap: thank you so much for your help in my questions of airdrying clay...... being a clay virgin it has helped a lot. clay is clay to me but when wendee and I were looking for something new to try we discovered this medium. wait till we try airbrushing !!!!!!

again thanx so much

11-13-2005, 12:33 AM

I have only used air dry clay a couple times, a mix of the red and grey kind, built up over a wire and plaster armature.

In the example images included I built the form out of the mesh, covered it with plaster bandage, sealed the plaster with shellac and added the clay. The clay is only about half to one and a half inches thick in areas. The clay works and acts the same as a regular terra cotta clay or other water based clays. To keep it miost while working I just sprayed it now and then and covered it with a plastic bag.

The clay in this case was just intended as a model. I subsequently made a plaster waste mold and a cast in cement from it. The seccond two images are of the cement cast.

In the end I let the clay dry out completely. It did crack, everywhere and some of the thinner pieces broke off. All clays shrink so letting it dry out over a rigid plaster armature will ultimately result in cracking. I assume that if the clay was not too thik and over a pliable armature the crackign would be minimal. When this stuff is dry, it does not have much strength, however now that it is sealed, I can bunm into the piece / move ti around and it does not fall apart. I sealed it with white / clear shellac and used some shellac to fill the cracks. It gave it a very nice aged look with all the cracks. Shellac works great to seal porus surfaces. A few coats built up will darken the clay and give it a high gloss look. First two images are of the air dried clay model.

11-13-2005, 11:05 AM

I like your sculpture. The cracks actually look really cool on this piece. The two headed gargoyle is really fun and scary all at the same time. Your cement casts look nice as well and will last a lifetime even outdoors. Thanks for sharing this.:)

11-26-2005, 11:06 PM
You know, all clay is air drying but oil based clay takes longer. I have a piece from 1974, oil based clay and it is pretty darned hard. But the cracks that occur often come from clay drying too fast. Wrapping in lightweight plastic, like kitchen bags, with a damp sponge near the piece can help. You shouldn't spray the clay with water or lay wet cloth on it because that will make the surface more damp than the interior and that can cause cracks. A tight sealed box can help a great deal and like a tobacco jar you have a bit of damp sponge or apple to add moisture to the air, then the clay won't dry very fast. You can make a box out of plywood with weatherproofing on the lid and then put a small bowl with the wet sponge in it next to the sculpture. Paint or otherwise seal the box and it should hold for several days. When I worked in the sculpture studio at Skidmore College I had to learn how to wrap my sculptures as I also maintained the kilns and sometimes it would be a few days before I got back to my own work.

Angela Baila
10-01-2006, 05:45 PM
I am just trying it out. Self Drying Ceramics were first meant for children's projects. My project too begins to 'melt' when it gets humid. Once it is completely hardened, in a dry warm room, then you could use a varnish of any sort to quickly put on the clay. If you play around with it too much, it will be like a ruined cake decoration exercise. If you could spritz on the varnish on very evenly at first, then let it dry, for a first quick plastification of your art... then, put on the thicker layer. This, will hopefully assure your piece from melting. In addition, I asked about firing this type of clay. I purchased mine from a clay company that deals specifically in firing clay... and they said that this clay could be fired on a low temperature Cone. Good luck.

10-01-2006, 11:12 PM
Hi Oliane, I was told by LIncoln Fox in one of his workshops to use Bone Dry clay. I could not find it for a long time and now I do see it listed in some of the catalogs. I am going to use it soon as I want to teach a workshop in sculpture with it. My students won't have access to a kiln.:wave:

10-06-2006, 04:40 AM
Hi Marilee, I have used air dry clay by Amcco and I was happy with the pieces, one was a life size bust of an African warrior and the other was small figure. I let the pieces dry slowly, then when dried to room temp. I sealed the pieces with 50-50 mix of denatured alcohol and shellac before painting. The pieces weren't as hard as fired clay but ok for inside use. Air dryed clay pieces have been found that date at 20,000 years old. How's that for lasting? Lou G.

12-19-2007, 03:13 PM
Hi everyone. This is my first post here and I found you by searching for info on the Amcco air dry clay. I've created a sculpture that is flat and allowed to air dry. There were two cracks which I was easily able to patch with water and more clay.

I want to eventually adhere this to a piece of wood that is vertical. I plan to shellac it and then paint it. It won't have any use accept as visual art. I'm hoping the shellac will make it hard enough to withstand any bumps or small bangs. I'm concerned about finding someone to oven fire it because I don't want it to shrink any further. Do you think it will work for what I need?

It's about 10 inches wide, 20 inches high, and only around one inch thick.

02-23-2008, 11:07 AM
I came upon this site while searching for an affordable source for self hardening clay. I usually buy at Hobby Lobby, but am looking for a better place to buy in larger quantity. I have used self hardening clay for years. Some of my first pieces fell apart after they got dry, but practice and experience showed me how to deal with this medium.
1. while in the stages of working with the clay keep your clay covered when not working on your piece, this keeps it moist and workable. Plastic wrap works wonders. Just make sure you have all of the air out of the wrap or bag once placed on the piece.
2. You can add bits of water to remoisten the clay.
3. a slip made from vinegar, water and a bit of the clay works wonders for repairs, and it's a great glue.
4. always let you piece dry completely, paint with acrylics or desired paint, and use a sealant to finish your work. This will protect your piece from moisture and allow it to last a life time with care.
I have several pieces that I made 10 years ago, that are just as beautiful as that day that I first made them. But I lost many pieces from not sealing my work. I was heart broken...
I hope this help you out.
Blessed Be...

05-15-2009, 06:01 PM
I came across Activ-Clay while searching for a product with which I could continue my 3D artwork while confined by the fact I had no studio space. I found Activ-Clay to be good sculpting clay and I was able to work over a two-week period - keeping it moist -with water/vinegar spray- and covered - the hardness it attained when dry was a pleasant find. After protectively covering the glass bead eyes with a coat of petroleum jelly, I sealed it with an outdoor acrylic spray paint as a base coat, and finished piece with craft paint, watercolor and gold leaf.

The only disappointment was my oversight in not keeping in mind the shrink-factor. It would be helpful for me to do a shrink test before I begin the next sculpture. (I formed this sculpture over florist foam -see very square back :(-and it cracked incredibly while drying - luckily, I am an old hand with water puttyand you can hardly tell where I patched the many, many fissures:smug:.)

You can find the piece under the gallery/crafting ideas section on their site: "'"Mother', a birdhouse"

06-06-2009, 09:57 PM
I've had some success with self-hardening clay by using armatures that allow shrinkage. Usually I use either newsprint alone, or a loosely-crumpled layer of newsprint over a wire armature. If the piece is robust enough, you can also hollow it after the surface dries, similar to the way you would hollow a sculpture destined for firing (though this does leave the air-dried clay sculpture more fragile).

That, and becoming adept at patching the cracks as they occur, lol.