Post 21 New Oval Pot Mould

I promised a few shots of the development of my next mould that I have been wanting to make.

The model for this pot is the one in the following shot.

It is a great ficus and the pot is beautifully suited to the trunk mass and inertia of the tree. I'd like to lay claim to it but unfortumately it's certainly not one I've got in my backyard. The pot has great proportions and visual appeal with just enough relief decoration to not distract from the tree.

So the place to start working this one up is to make what I would call an armiture, in sculptural terms. I first cut out the upper and lower oval shapes from a thin sheet of fibre board. These are then mounted either side of a shaped framework representing the body of the pot. I wrapped the framework with masking tape to provide a surface to clad with clay to shape the mould profile. This doesn't need to be too sophisticated - just robust enough to support the clay during shaping.

This is what the sandwich armiture then looks like. As you see it starts to look like the pot upside down.

 Then the armiture is packed out with clay - in this case just a good fine white terracotta clay. Any fine clay will do the job.

 Then a custom scraper, crafted to replicate the side profile of the final pot, is used around the outside surface to remove excess clay and cut down to the right size with a nice smooth surface. This shot shows the start of that process.

This shows what it looks like when the profiling cut is finished and ready to cast.

And if you invert a picture you begin to see what the body of the final pot will look like.

This is now ready to cast so it's time to get the dam in place. Obviously it is very important to make sure the dam is leak proof. There's nothing worse than having plaster squirting out onto the ground and trying to reseal it from the outside. Trust me I speak from experience. Any clay you use as as sealant will be exposed to the moisture in the plaster and water as the plaster dewaters if it does, so care is needed to make sure there is enough in place.

And here it is with the plaster poured into place, sealed nicely this time with no leaks.
Now sit back and reflect on a good job while it firms up.

The dam came come off pretty much after and hour or two but it otherwise it needs to sit for a couple of days undisturbed to firm up even more before removing the armiture.

 

As is usually the case the devil is in the detail and a few carpentry skills and equipment don't go astray as well.