This week I made three urethane molds of clay sculptures – a black-footed ferret, shown above; a walrus; and an Arabian Oryx. I intended to make a Caspian seal, but after it was done I decided a walrus would be more fun.
The other two models are shown above, after being sealed. The models were sculpted using water-based pottery clay. I allowed the clay to dry to leather-hard stage before making the molds. The ears of the oryx dried faster than the head, and I now realize I should have left them off the model, since they could be added after the paper mache clay was dry. Live and learn…
After the molds were done I then messed around with the paper mache clay recipe, changing it so it would be slightly easier to use in a mold. For that part of this project, I’m definitely still in the experimental stage, so any suggestions will be appreciated. I’ll show you what I’ve done so far with the clay recipe down towards the bottom of the post.
The clay models were sealed with a product called SuperSeal, made by the Smooth-On company. I ordered the sealer, the release, and the Smooth-On 40 rubber mold compound from Farwest Materials in Walla Walla. (They have great customer service). After the models were sealed, I sprayed on the universal release, and allowed the excess to evaporate. Then I mixed up the two parts of the rubber compound and brushed it over the models.
I allowed the rubber to set up to the tacky stage between coats. After four coats were added the mold looked like this:
After drying overnight, I made a support mold with plaster of Paris:
When the plaster was hard, I removed the clay model. The mold is now done. You can see that I cut the rubber mold at the ears, to make it easier to remove the finished piece.
Now for the fun part. I tried the paper mache clay recipe just as we normally make it, pressing it into the molds in a thin layer about 1/4 inch deep. There were two problems – the clay takes a very long time to dry because air can reach only one side; and small voids mar the surface of the piece where the clay doesn’t fill the mold correctly, no matter how carefully I pressed it into the mold.
For the first problem, I tried using a fast-setting joint compound to replace the regular product we normally use, but my efforts weren’t very successful. It seemed like such a good idea, but…
In the end, I came up with a variation of the recipe that seems to work, although I can’t give exact measurements. Lots of experiments still need to be done. I mixed up a small batch of wet toilet paper, just enough water to cover the paper in a small bowl, and Elmer’s Glue-All. This made a “soup” with a lower paper content than the normal recipe. I then mixed in some corn starch and some plaster of Paris. The corn starch helped the mixture stick together so it was easier to work with, and the plaster caused the mixture to set up so it could be removed from the mold fairly quickly. Obviously, with the plaster in the mix, I needed to work a bit faster than I normally do.
I used a soft brush to paint a thin layer of the mixture into the mold, and then covered it with about 1/4 inch more.Â Using the brush and a thin layer helped reduce the number of voids on the surface. As you can see from the photo, the “clay” I mixed up has a consistency like whipped cream cheese. I mixed just enough for one mold at a time, and each mixture came out a little different.
The ferret and the walrus have now been taken out of their molds – I’m still working on the oryx. The plaster has set up, but they are still very damp, and will need to dry for several days. Then I’ll make the walrus’ tusks and the oryx’s horns, fit everything together, and paint them. I’m still not sure how they’ll be mounted – I definitely want to avoid the hunter’s trophy look. Suggestions?
Since the first pieces have not yet dried, we still don’t know how strong they’ll be. They’ll be hung on a wall so they don’t have to be totally unbreakable, but I do need to be able to move them around without worrying too much about breakage. I hope to have at least 12 different pieces finished so I can take them to an art fair at the end of August. You can see the plastic mesh that I’m using to reinforce the pieces below, under the ferret. I might also use some traditional paper strips and paste on the insides of the pieces to make them stronger, if needed.
I’m really looking forward to seeing the walrus and oryx with their tusks and horns. I originally intended to only design smaller items for the molds, like the ferret, that I could easily ship – but once you get your hands in clay, who knows what will happen?
As always, your suggestions are welcome. And if you’ve done similar experiments, please let us know how they turned out.