Tuesday, April 17, 2012

Making a silcone mold and wax pour

Another lesson learned: two right angles are difficult and time-consuming to produce in bronze.

My bronze sculpture, "Ascension"  is the woman that is rising from the base, supported by the cloth that is draping off of her hips. While I love the waterfall effect of the drapery, in reality, it causes a lot of headaches for the wax chasers, metal chasers and base makers. It also makes production more difficult, time-consuming and costly.

Additionally, the foundry mold-maker misunderstood my instructions and added wax to the back of the fabric in the mold-making process that required hours for me to remove and chase.

So, since I learned that the the two right angles are a problem and the current cloth in wax required so much time (every single time one is made!) I decided it would be best to sculpt a new section to the drapery to replace the one that they were currently using. I took the existing wax, removed the mistake in the back and designed new draping to the bottom that just clears the base. This will limit the sculpt to only one right angle (thus making production much smoother) and will also reduce the chasing done by more than 3/4 of the current time spent on this one part of the sculpture.

Once I perfected the wax fabric, I made a pour mold and then did a sample wax pouring. I was pleased that it worked well on the first try, enabling me to get the new chased wax and the new mold to the foundry so the next two in the edition can begin their process into becoming bronze #2 & #3 of 33.


  1. So this isn't a rubber mold I take it? Interesting..

  2. Actually it is rubber. Apparently there are different kinds, like silicon and urathane, etc. and the foundry said that they would like the mold to be silicone. I'm an awful mold-maker and frankly have no interest in it...but as they were going to take 3 weeks (plus charge me) I saw no way round it. I asked some questions and visited youtube a lot. I had some Smooth-On Dragon Skin left over from my first mold experiment and used it to brush on a skin coat. Made a mold box out of a hair product bottle that I cut the top off of. Then mixed up the rest of the Dragon Skin and poured it in- and found that I was about 3" short! Luckily I had just bought some Poly-tek silicone rubber too, as back up. I quickly mixed that up and added it to the Dragonskin that I had already poured. Then crossed my fingers ;-)

    The next morning it was ugly, but firm. So I took a knife and began cutting into the mold in a zigzag pattern. It was nerve-wracking but I did it. Then I melted and poured the wax and it came out rather well!

    Still don't love mold-making and would only do simple pieces - but it saved a lot of time and some money. It probably cost me $40 in mold making materials. Not a drop in the bucket - this stuff isn't cheap...but still....