Plaster Carving Experiments - Part 2 Assessing the shapes

Some of the shapes I have recently carved in plaster may not be successful when weave is applied over the surface, any fine details in the carving will be lost and not transfer into bronze.

I think moving forward the shapes of the plaster need to be simple and smooth. If they feature any voids or holes the weave should be able to pass through without blocking the space completely. If it passes through and fills the gap would this create more interest when cast? or would this cause a problem for the foundry?

The finished plaster blocks that will go through to the casting stage need to be fitted with a metal rod, this is to make sure the block is held mid air and thus not crushing the wax weaving that will be applied later. Will a metal bar sticking out of the plaster block be a hinderance to my carving?

Fitting the metal rods inside the plaster blocks prior to carving may be tricky as they need to be inserted into the plaster whilst it is wet and not yet set. Possibly the rod should be inserted prior to vibration, but I need to think how the rod can be secured whilst being vibrated as this may create more problems.

Next step - make 5-6 blocks of fine casting plater, carve them and then weave onto them using cord to see how the weave works being applied to a solid. Potential problems could be; not be able to work the weaving on both sides, getting the weave tight enough that it does not sag away from the block and trying to retain the overall shape.

Plaster Carving Experiments - Part 1

The plaster carving period has been successful, I can now create a number of forms working first from a drawing, then scribing the outline onto the plaster, then finally carving.

Hammer & Chisel

The best results so far have been using the hammer and chisel to cut away the waste in large chunks. This leaves a very rough surface and I have found that if the plaster is still fairly damp it can be made finer with the chisel and using my hand to apply gentle pressure. If the plaster is drying out the carving is harder as mistakes are easily made, it is too easy to gauge out too large an area. I’m not sure if this is the correct method but before cutting away a large area I use the hammer and chisel to deepen the scribe marks to create a small v-cut, this seems to prevent the plaster chipping away behind this v-cut.

Surform Tool 

This is great for making large sweeping curves if the plaster isn’t too wet. If the plaster is freshly cast then the Surform tool clogs up easily, if the plaster has stood for a few days first then I have found the Surform performs better. At first I was washing the tool at the end of the day, I have found that leaving it on the radiator overnight works as the plaster dries up and after a few taps of the tool the plaster just falls away.

Drill

Using a cordless drill and a flat ¾ inch drill bit has been great for removing inner areas of plaster, it works well at a medium speed and not forgetting to pull out the drill bit from the plaster block to remove any plaster that has adhered itself to the drill. The drill saves such a lot of time especially when wishing to remove a large channel of plaster from the centre, drilling multiple holes in a line and then breaking through the small areas between each hole with the chisel to connect each of the holes.

Scrapping tools

I found a collection of tools for potters which had two scraping tools that look a bit like an open potato peeler. I have found they are only suitable for very light gauging and finishing. They seem to be better when the plaster is damp, I use one yesterday on really dry plaster and the squeaking was terrible as you worked the tool over the surface, something to be avoided if black boards being scrapped with finger nails is something that makes you shudder.