Thursday, July 8, 2010

Mold Making, Day 4 - Awesome

Started today by finishing up a few sections of the mother mold, then cleaning up the studio again. It's a small studio, and every time it's time to start a new task, I've got to re-organize the place.

With the mother mold completed, the last step was building wooden frame to support the mother mold when it's inverted, and to help keep all the pieces in place.

With that accomplished, there was nothing left to do but open the mold. Nerve-wracking.

I got started almost by accident, seeing if one of the feet would come up. Once it did, there was nothing to do but pull up everything.

I called out the wife and kids to watch, and then immediately regretted it. In my experience, opening a mold for the first time, even one you feel good about, is a harrowing experience. Not something you necessarily want to share with hot, bored, kids who aren't allowed to touch anything.

My wife, sensibly, got everyone out of the studio until I called them back to watch me peel back the rubber.

I haven't had a chance to inspect the rubber inch by inch, but from what I can tell it all came out beautifully.

Here's what the mother mold looked like popped out, reassembled, and resting comfortably on the wooden frame.

And here, finally, is what the rubber looked like, snugly registered in the mother mold. I don't think this makes me a genius, but it's a long way from my comfort zone, and it certainly makes me feel like one.

It looks good. The question is; can it produce a great cast? Stay tuned.

Wednesday, July 7, 2010

Mold Making, Day 3

Wednesday was spent putting the mother mold together.

In making a multi-part mother mold, each new piece is either defined by a clay wall, or built up against the (heavily lubricated) wall left by the previous piece. The image below has examples of both. In this case, the mother mold is composed of strips of burlap dipped a special plaster called FGR-95. FGR-95 is really meant to be used with fiberglass. I've built a lot of sculpture with FGR-95 and fiberglass (some of which can be found here), but that was in grad school, where the school supplied the fiberglass. Now that I'm paying, I'm using burlap.

Below is a bad photo of interesting moment. At this moment, I was midway through building the largest section, when I realized that the parting line I'd started wasn't going to release. The pieces of a mother mold aren't manufactured like a jigsaw puzzle, they're thick and imperfect. They don't slide neatly in and out. If they're too complicated, they don't go back together.

Sadly, I only realized I'd designed a locking system when I was putting in the second piece, so I had to improvise. Now I've got two little subsections in the middle. In the end, though, I'm not sure I could have done it another way. There's big undercuts there that could cause problems when it comes time to get the cast out. So I got lucky there.

Here's what it looked like, more or less, by the end of the day Wednesday.

Tuesday, July 6, 2010

Mold Making, Day 2

Kind of a light day. I was pretty wiped out from yesterday, and the 100 degree heat made it seem like a good day to take the kids to the pool.

Here's what it looked like at the end of the day Monday.

And here's a pretty good shot of the registration bars that Justin suggested. When you're making a rubber mold, you're essentially making two molds. There's the rubber, which (hopefully) captures the surface of the sculpture. Then there's the mother mold, which captures the underlying form. We tend to focus on the surface (that's where the features are, details, and evidence of the artist's hand are), but surface without form makes no sense. Without a solid, well-registered mother mold, the sculpture will bend and distort, and all those lovely surface details will be a moot point.

First thing Tuesday was clean-up, after which I made sure everything was lubed up (more vaseline and mineral spirts), and then built the clay wall for the first piece of the multi-part mother mold. Building a multi-part mold is like building a large, three-dimensional jigsaw puzzle where the pieces are defined by the topology of the underlying rubber, and by how easily the individual pieces will come apart and go back together. The goal is strike balance between fewest number of pieces and ease of release. It's complicated, and after I got the head done, I decided to do the rest of it on Wednesday.

Monday, July 5, 2010

Mold-making, Day 1

An incredibly tiring, but (apparently) successful day.

It was supposed to get to 100 today, and I wasn't sure my window AC unit would keep the studio cool enough to prevent the mold rubber from being effected, so I got an early start.

First step was to build a clay wall to catch the rubber as it runs off the mold.

If the figure looks shiny, it's because the second step was to coat everything with vaseline (thinned with mineral spirits). I used about a 50/50 mix to paint the base, and a 90/10 mix in a spray bottle for the figure itself.

After that, I whipped up a quick foam-core mold that I filled with the mold making material, which eventually set into long strips of hardened mold rubber, about 1/2 x 3/4 x 20 inches long. Later, I pinned these to the sticky surface of the mold to ensure proper registration between the rubber and the mother mold. This was Justin's idea, and it looks to have worked out great. Thank you Justin

After that, there was nothing to do but pour the rubber. I'm using Polytek 74-29 (also on the advice of Justin and Darla), and one of the cool things about it is that it's black. Looks like a Gulf Coast vacation.

The first pours were easy. The 74-29 is a little more viscous then some of the other materials, but it moves easily, and fills nicely. It didn't take any time to get the whole figure covered and looking like this.

From there, things slowed down considerably. The problem with brush-on molds (as opposed to poured box or blanket molds) is that that you spend a lot of time moving the material around, waiting for it to set up. You can thicken the material with cab-o-sil or polyfiber II, which I did, but getting it where you want it is still slow, tricky work. A little like trying to ice a cake with motor oil.

The other problem is that it's hard to know when you're done. In theory, the goal is to get an even 3/8ths - 1/2 inch layer over the entire piece. In practice, after you get everything covered, and touch up the obvious light spots, it's hard to figure out depths. The hard part is that if there are thin spots in the rubber, you won't know it until the end, when it's too late. Better to err on the side of caution, add another layer, and hope for the best.

Friday, July 2, 2010

Phase One Complete

An anxious day despite having plenty of time, being ready, and having great neighbors. It's hard to decide that a piece is really, irrevocably done, and the next phase, mold-making, always makes me nervous.

Here's a picture of what it looked like today around 2:00pm, when I wrapped up the modeling and started cleaning and rearranging the studio.

Here's a detail photo of the fletching on the arrows.

And here's 3 nice people helping me get it horizontal, and ready to start phase two.

My thanks to Matthew, Hayes, and John. Cold beers well earned.

Mold making starts Monday. Stay tuned.

Thursday, July 1, 2010

Ruskin On Gothic Sculpture/Sculptors

"This character follows necessarily on its extreme love of truth, prevailing over the sense of beauty, and causing it to take delight in portraiture of every kind, and to express the various characters of the human countenance and form, as it did the varieties of leaves and ruggedness of branches. And this tendency is both increased and ennobled by the same Christian humility we saw expressed in the first character of Gothic work, its rudeness. For as that resulted from a humility which confessed the imperfection of the workman, so this naturalist portraiture is rendered more faithful by the humility which confesses the imperfection of the subject."

-- The Stones Of Venice