Post #215683 by hmc on Sat, Feb 18, 2006 9:59 PM

Plaster mold creation.

First of all, to make a 4 wall box:

I made mine out of left over ply.

I screwed the pieces together and used a silicon bead along the edges to fill in any gaps. If you leave the gaps, the plaster will just seep out!

Starting to "fill in" the base with more modeling clay (same stuff used to make the original master).

I built up the clay until the silicon master was elevated to the centre/middle of the box.

Once I reached the centre, I started neatening the edges along the silicon master. This is known as the "part line".

Spend most time on this area as if it isn't done neatly, there will be a noticeable part line down your mug.

Once finished, I popped in some indentations (I think they are referred to as "keys"). These will act as your locking mechanism when keeping your 2-part mold together in alignment. I just used the end of a thick marker.

Now it's ready for the plaster pour. I used Ceramical, 40m part water/100 part plaster. It dries in about 20 minutes! And as all plasters do, it heats up when it goes off (off as in hard, not smelly!)

Once the plaster had dried, I turned it upside and started to remove the modeling clay from underneath. The moment of truth!

This is what it looks like with all the clay removed. It's now ready for the second plaster pour.

Tomorrow it's off to buy some ceramic slip to start pouring the mugs. Depending on how long the slips take for each mug - I may be making more plaster molds to speed up the production line.

Hope you're all getting something out of this!