Structural Support Considerations

Whenever I build my pod shaped vessels, I have to think about how to fire them in the kiln for bisque fire and at higher cones, for example at cone 5 or cone 10.

In this piece, I wanted to use the Van Gilden’s flashing slip which cracks really nicely at Cone 10 so I had to design a structural support system that will be strong enough to survive a Cone 10 fire.

The donut ring and supporting tubes were all assembled from bone dry paper clay pieces using dry to dry techniques (top picture).  

As my pod is rather heavy and tall (36” high), my support has to be well constructed to withstand any movement in the kiln during firing. The legs were thick slabs rolled into tubes.

Lateral struts at the bottom were added to give sideways rigidity.

This is structural support for my pod which can be seen in the background. The Van Gilden's flashing slip has been applied to it. It's bone dry and it's ready for bisque firing.

 In a way, the structural support is like a piece of sculpture in itself. I plan to reuse this support for future works.

My Paper Clay Way of Making Masks

My preferred way of making masks is to make a bunch of these generic masks from a master mold, let them dry completely and then alter them. This way, I can store these bone dry "mask-forms" indefinitely until I get the inspiration or motivation to work on them. The picture on the right shows the plaster mold. Fresh paper clay mask are on the left.

Facial features can easily be changed, modified or even removed. At this point, I usually work by adding wet paper clay to the bone dry base, building up layer upon layer. If a jaw line needs to be drastically altered, I use a dry wall saw to effect such a major change. The bone dry form can also be wetted down to reconstitute the plasticity of moist paper clay so that contours can be reshaped.

I'm working on a new set of 3 Japanese masks. I'll post them soon.

Paper clay And Structural Support

Case Study: "Within Us"

This is the completed piece. It is mounted with a stainless steel pin into a solid textured aluminum block.

The issue arises when it comes time to fire the piece, first in the bisque fire and then to Cone 10 reduction. Due to the shape of this piece, I knew I had to create some kind of a support or scaffolding to prop up the piece during the firing process, and one that is strong enough to withstand a high fire at Cone 10.

The scaffolding was made from paper clay with a combination of dry-to-dry and leather hard-to-dry joining techniques.

Creating a piece is one thing, completing it is another. In a piece like this where there is no stable base for the piece to rest on, I had to devise something. Paper clay allows me to easily "engineer" this support to accomplish this end.

For the story behind this piece, click on this link.

This piece is in a private collection in Orange County, CA.

Paperclay & Shrinkage

One of the things I get asked with paperclay is "How much does it shrink?" That is a valid question and after all, it's good to know all the technical details of the clay when one is working with it.

The paperclay and subsequent technical infomation provided here is manufactured by IMCO in Sacramento. It's a proprietary blend and is carried locally here in So. Calif by Aardvark Clay Company in Santa Ana, in 25lbs bag.

The information provided here is from my own experience.

From green to bone dry - 5 %

After bisque - not measured

After high fire (Cone 10 reduction) - 10%

Total shrinkage is around 15%

Considering other traditional clay bodies (total shrinkage ) is anywhere from 8% (low end) to 12-13%(high end), this paperclay shrinkage is quite a bit. It's good to know so you can compensate by making your pieces a bit larger than you normally would.