Tag Archives: DG

Venus designing

To build a larger sculpture from a small clay sketch uses some strategy to make the enlargement work without distorting to design. It’s said the Henry Moore worked his designs out in the size of something which could be held in his hand. That size is very helpful since the object can easily be turned in the hands and all sides studied and worked on evenly, and the contact of the hand, the Great Tool, is equal on all the parts of the object.

My way is to convert a small clay model into a design plan which I can measure and build from. To try and measure accurately from a small model and make enlargements of dimensions is too inaccurate. The model is freehand, and not symmetric, the enlargement scale is too great. I want to derive a schematic drawing which has the essentials of the design laid-out accurately on a grid, which can be enlarged and dimensioned from as needed when building the sculpture. I know my friends in digital computer 3D modeling are appalled, but this is an ancient tried-and-true method of building, anything, from a simple plan or sketch. As well, this design work will help me if I choose to also produce a 3D model, since the proportions of the design are already set down.

I’m working from my last idea, which has taken on the identity of a Venus, or else a proto-woman. I had hesitation about this, but I did get approval from women about it so of course I’m going ahead.

Take clear photos of the model, front, side, back, top, and bottom. Use a deep focal length to flatten out the image and reduce the perspective.





Open then in some software, maybe Photoshop, stack them up in with some transparency, and scale and rotate them so they’re even and of consistent size and orientation.


Then, lay them out in graphic design software, maybe Illustrator, and set some guidelines across their common points of reference.


Draw the design over the images, constructing from the reference points. The image is just a suggestion, you’re creating a new design, not just tracing the image exactly.


With judgment, refine and clean up the drawing.


Turn off the images layer, turn on a grid. And perhaps you have a useful schematic,


..which you can blow up to any size, print out, measure from, and trace onto any material, say, a block of wood, prepared for carving.

Silicone back

I’m doing the second side, the back side, of silicone mold. This repeats the steps done for the first, front, side. Of course, the mold is turned-over now. Apply a liberal amount of release to all the surfaces of the two halves, the one with the model sitting in the silicone of the front side, and the other, back side plaster. Where silicone will meet silicone there must be a barrier of release or else the two halves will bond permanently. It is surprisingly easy to neglect this for some reason, when one is pre-occupied with so many details to consider. I apply paste wax (Briwax) to the plaster, several coats, and a spray type release I’ve mentioned before, which is hydrocarbons in ether, or something. Works fantastic. I’ll say it again: APPLY A LIBERAL AMOUNT OF RELEASE TO ALL SURFACES. If you can’t remember clearly applying release, then do it again.

Assemble the plasters, strap it together and again, cover the feet/pour spouts area, sealing it tightly so there will be no leaks.


And that box mold I’m doing on the side? I added some pour spouts there too, and applied release. I’ll pour the second half right on top of the first, with whatever’s left over in the bucket from the big mold.

Here’s the mold, with the silicone poured in. Like before, there are vent holes at the high spots which let air escape the mold as the silicone fills it. The clay plugs the holes when the silicone oozes out. I have again mixed up 250% of the volume of the clay blanket removed in the last step. It follows the formula: The weight of clay times 1.06 equals the volume cubic inches of the clay. The volume cubic inches times .68 equals the weight of the Mold Max 30 silicone product that I’ll need. The rational about qualities to mix up are all in the earlier post “Silicone front”. On that first side, it turns out I had a good bit of silicone material left over, even after the box mold was poured. Based on weighing the leftover amount, just doubling the volume of the blanket would have been enough. And although I know this, I’m still going to use 250% volume, to be safe. It is a large batch, as much as I can get into the vacuum tank at one time.


Enough to fill up the box too.


After curing for 24 hours, I open the foot-cover to see. It’s all good, but do notice that 10 grams of material has leaked into the left spout. The seal wasn’t perfect.


Split the mold open carefully, slowly, gently.



The mold, by chance, opened with the first side facing out. This side hasn’t seen the light before, and it’s our first look at it, but it isn’t the side we just poured. It looks good without any air gaps at the high spots – all the venting worked properly.


I want to free the other side. I invert the whole thing and suspend it on some cups to let it, sort of, ease its own way out, for a couple of hours.


Then I gently start to pry it away from the plaster shell…



..until it is worked loose.


Interesting. See the air gap there on the belly of the figure? Although there had been oozing silicone out of that vent hole before it was plugged, there must have been some subsidence of the material while it was curing, leaving that void.


I think it may be the same amount of material which found its way leaking into the foot-funnel. Or perhaps, because I forgot to seal the edges around the plaster half with the blue tape, air got into the mold and allowed the subsidence to happen. Otherwise, the clay plug should have secured vacuum to hold the silicone up. Who knows, but in this case it is easy to fix. I’ll re-assemble the mold and pour some silicone directly down the vent hole and fill the void. Since I will not apply any release to this area, the new materials will bond tightly to what’s there.


After 24 hours I open the mold and see that the repair is good.


Shell fini

The box removed, and the plaster shell mold smoothed.



I’ll just let it cure, dry, and harden up a little longer, so when I split the two half apart, very gently, I won’t crack either half. The clay underneath undulates a lot, so removing the shells evenly, in one piece, using small wooden wedges, will be  a trick.

Meanwhile, on the side, to use up the free time, I cast the Beachstones molds I made last Fall in urethane resin. (The waxes I made earlier from these molds for bronze didn’t work out too well and I’m going to do them over, soon I hope.)



It still needs finishing, but I’m very please with the way it turned out – that’s saying it came out looking like I’d hoped – like beach-glass, you know, that sand-smoothed broken glass you find at the beach. Look forward to more.

Back plaster

I boxed up the mold, preparing to pour the plaster for the back side. I just build this quickly using foam-core, hot glue, and tape, lots of tape. I seal the inner seam of the box with clay where it meets the front side plaster so there is no leaking out of the new plaster. I line the inner side of the box with packing tape to release the plaster. I added the sprue and vents for the silicone to eventually pour into, in the form of cardboard tubes and soda and cocktail straws, but that step is still a way off (the clay under the plaster will be removed and replaced with poured-in silicone, forming an inner blanket which is supported by the solid plaster outer mold). It’s a lot of details with not much to picture.




Mix the plaster, something I’m not showing you, pour it on and shape it up. You can see some markings above which I use to estimate the thickness I want from the plaster.


I’ll let this dry a few days, take away the box and smooth it out some more.

It is a relief to be at this point. I’m maybe halfway done, but some of the most critical planning and preparation steps are complete now, and if I’ve done this correctly, most of what follows will be clean straight-forward work without anxiety.