A second attempt

I had this terrible image, driving back from our Thanksgiving trip to Ohio, of a picture like this one posted to the blog each day as I tried for yet another usable rubber master. Hopefully this second attempt – poured this morning – will be all that’s needed.

And here is the first attempt sitting inside the gusset piece. The speckles on the gusset are air bubbles trapped inside the translucent rubber. My little foal, however, is almost entirely bubble-free, so my experimental trick worked perfectly.

I’m going to have to describe the trick in words. I really didn’t have enough hands to make it work and I had to work quickly, so taking pictures as I went wasn’t possible.

I started with the mold opened, and mixed my rubber. Then I dabbed a little bit of rubber onto the face and furry sides – places where air bubbles tend to get trapped. Once I had enough rubber to coat the face and the body, I lightly sprayed the surface with the airbrush to remove any bubbles. (The first time I sprayed too hard and sent rubber flying outside the mold cavity, but it wiped off the mold easily enough.)

With a thin layer across my potential trouble spots, I then reassembled the mold and poured the rubber as usual. (The first picture in this post was taken right after that was done.)

The tricky part is that you have to work really fast, because the rubber is setting up and it still needs to flow through the whole design area. Rapidly managing the mold, tools for dabbing, the airbrush, the rubber bands, and the rubber mix can make you wish for six hands. Or for employees! But if the end result is fewer air pockets in the master, the scramble is certainly worthwhile.

With a little luck this second pour will have all his parts, and I can show how the rubber master translates into a plaster mold.


5 Responses to A second attempt

  1. DrSteggy December 2, 2008 at 3:22 pm #

    the little rubber foal makes me squeal with happiness–I have a resin one, and I can imagine the clinky version as similar to the HR foals–is this method of mold making similar to HR but more complex?

  2. Lynn A. Fraley December 2, 2008 at 4:43 pm #

    Brilliant technique Lesli! When Barry was casting the resin Imps, he hand painted resin in the open mold, (especially the tight spots like the ears), then closed the mold to pour in more resin. The molds were then placed in a pressure pot while the resin cured. This did a good job of eliminating the vast majority of any other bubbles. These itty-bitty pieces really present some technical challenges — but oh so worth it with such an adorable sculpture!

    ~ Lynn

  3. Lesli Kathman December 2, 2008 at 10:27 pm #

    Hey Jackie! I honestly don’t know if Hagen-Renaker used rubber master molds. Perhaps if Joan is reading, she can chime in since she knows a lot more about how things were done there.

    And Lynn, that is so cool about painting in the resin. I had been so impressed with the casting quality on the resin Imp. I had no idea that was how he did it, though! That’s how I get the slip into the tiny details on some of the ceramic beads I have made, too. My experience with the beads made me think of trying it with the rubber.

  4. Joanie December 3, 2008 at 4:59 pm #

    Jackie, this isn’t exactly how HR did it. They made a block and case, instead of a rubber master. Their block and case would have looked more like if they had cut the little foal in pieces, and sunk each piece into the surface of one mold. So, each plaster piece would have been poured from a mold made just to form that piece. It’s weird. But they used that method because then they could pour all of the mold’s pieces at one time. Quicker for production. Joanie

  5. DrSteggy December 3, 2008 at 7:53 pm #

    Thank you Joan and Lesli for the explanations

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