Two Part Mold Making
Due to trying new materials for the first time, yesterday's results were (as I should have expected) unexpected. The three parts of the mold I was creating solidified into one solid piece causing a real horror of a demold. In lieu of that, I went back to the material I'm more familiar with and made a 2 part mold of the Rook chess piece. Don't get me wrong, there were still unexpected things, but nothing major... nothing broken.
The key to measuring and making a proper barrier around the piece is to be sure to give yourself plenty of working space. The piece will need to be half buried in wet clay, so the more space you have to do this the easier it is. In hindsight, I probably could have given myself a little more room.
Hot gluing the feet to one cardboard wall will keep the rubber from completely encasing the Rook. This step ultimately provides a place to pour in the liquid plastic compound when the mold is done.
We will also need to seal the the clay around the Rook (and the walls too). Once complete, use the "roundy" end of something to create the keys in the clay. I used the butt-end of a fat marker.
One of the most useful tricks I've found for measuring how much liquid needed is by filling the mold with uncooked rice (do not eat). Pour the rice from the mold cavity into a cup and you'll have a pretty-darn accurate idea of how much liquid rubber you'll need for "part 1" of the the mold. I know from experience that I can pour this rubber 5 minutes after the release agent has been sprayed.
Once the rubber dried, I flipped over the mold and removed the clay that encased the Rook. The brown glob in the above -left image is where I didn't seal the edge around the rook well enough... cut it off... that's it. Without removing the Rook from the rubber, removed ALL the clay. Any little bits left behind will affect the shape of the mold... and not in a good way.
When all the clay has been removed from the rubber "part 1," measure the second mold cavity's volume, spray the release agent, pour the rubber...Bada-bing! Bada-boom!
Now, I'll be experimenting more with the blue rubber from the last post, but now we see how it's supposed to work!