Monday, March 15, 2010

Perlite and Paperclay - Part II

This hand pinched form was made from perlite mixed with my regular sculpture paperclay. (Sold by Aardvark, Santa Ana, CA. This was their old batch of paperclay from IMCO, Sacramento. Aardvark is now making and carrying Rosette Gault's formulation for her own patented P'Clay™)

Enough perlite was mixed with my paperclay to give a good texture on my form. The piece was first bisqued. The resulting voids were exposed by sanding the piece with a metal rasp. An iron oxide wash was applied on the outside of the piece while the inside was glazed with carbon trap shino. The piece was fired to Cone 10 reduction. Size of the pinch form is 3.75"H x 4.5"Dia.

My observations:
1. Compared to my normal addition of using cooked rice as an organic inclusion, the perlite gives a wider assortment of void sizes - ranging from the size of coarse sand to almost 1/4" in diameter. Cooked rice gives a more uniform void size.
2. Some of the perlite remaining in the voids melted at the Cone 10 temperature and this is seen as a slightly opaque glassy residue in the voids.
3. The perlite inclusion at the bisque stage is more resistant to sanding with a metal file compared to other organic inclusions, for example, cooked rice or rice hulls.
4. The piece is rather light so you do get the benefit of a weight reduction.
5. There was no "blow out" from using perlite.

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