Friday, September 3, 2010

Roll up down - the Rim

Sisters - in their  Sunday Best - extruded paperclay square coil on inside to thicken rim
Slab built vases always tend to have weak rims unless you make the slabs thick. Since we pay by the pound for firing at our guild I try to use thin slabs but this leaves me with a very thin rim that somehow looks unfinished and weak. I have tried adding extra slab strips to the rim but would get cracking at the joins especially in the corners. Then I started using a soft clay coil so that there was no discernible join in the corners, roughing up the top seam and filling in with extra clay - still some cracking but just in the top seam. I then switched to a soft paper clay coil and that seemed to eliminate the cracks, however I did have trouble getting a crisp edge.

Rolled down rim - punctuates rim
 The best was extruding a length of paper clay using my clay gun and the small square die. "The Sisters - in their Sunday Best" - has got a rim produced that way. As the back was higher, I needed the rim to show crisply on the inside. 
Another method that I tried was rolling and thus compressing the rim with a mini rolling pin - a method that was suggested to me by Steven Hill in one of our journey workshop sessions. That worked for the small handbuilt box but for large pieces as my slab vases it did not result in a sturdy nor thick enough rim for me. Perhaps if the slabs were softer when I rolled them it would have given thicker results.

But for now it's paper clay and a clay gun  for the slab vases.

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