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Budget Silicone Molds and Castings 
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Unread post Budget Silicone Molds and Castings
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When I was in college, with a typical college student's budget, I learned that household silicone caulk can be quite useful. I have used it a number of times to make molds, as well as casting flexible pieces with it. The stuff is VERY cheap (usually just a few dollars per tube), so it's great for when you're working on a budget. It is not as easy to use as a professional grade of art silicone.... but sometimes a bit of extra effort is worth the savings! It can be found at any hardware store, or at places that sell household repair supplies.

If anyone has more information or advice, please feel free to share!


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- Get the type of caulk that comes in long tubes with a pointed plastic tip. You will also need a caulk gun, which isn't expensive. It's just a holder for the tube, and a squeeze trigger that pushes the caulk through the tube. All you need to do is place the tube in the gun, cut the tip off the applicator, and you're ready to go.

- Experiment with a few different types of caulk to see what kind works best for you. I like the clear kind, so I can see my model through it and better judge the thickness of the silicone.

- You should still always use a mold release to make sure the silicone doesn't develop a permanent attachment to your model. It's also wise to spray your model with Krylon Clear to seal up any pores it may have, because silicone can really lock into every little divot. You might want to do a small patch test as well, just to make sure that the silicone won't lock onto your material, and to make sure that there's nothing in your model that might inhibit the curing of the silicone. Better safe than sorry!

- There are two ways to apply the caulk. The simplest way is to just apply the caulk straight from the tube and directly onto your model or into your mold. If you dampen your fingers with soapy water, you can hand-shape the silicone as you work and it won't stick to your hands.

- If you wish to use a larger amount of silicone at one time and not deal with the tube as you're working, then get a bucket and add some soapy water. Squeeze the caulk into the water until you've got enough. The soapy water will keep it from curing too fast, and will keep it from sticking to the bottom of the bucket or your hands. Pick up the silicone with your hands, and pat it into place on your model or into your mold.

- If you only use part of a tube, it can be sealed so that the rest can be saved for later. Duct tape over the end of the applicator works.

- After the silicone cures, it can be cut open with a utility knife or Exacto if necessary.

- If you want to actually cast something in silicone, rather than just making molds with it, keep in mind that silicone is flexible and very smooth, and most things won't stick to it... so it is very difficult to paint. They do sell caulk that is designed to accept paint, though. (Usually so you can use it to seal around doors and windows and then paint it to match your house trim.) If you plan to paint something cast in silicone caulk, make sure you get a brand that says it can be painted!


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To prove that silicone caulk can work very well for mold making, here's a bronze casting that was made using a household caulk mold. I started with the two models, clay critter and wood, which I coated with a heavy layer of silicone caulk. The caulk was backed with a plaster two-part support mold. Once the plaster was hard, I took it off and then cut open the silicone mold with a utility knife. Because silicone is so flexible, I only had to cut a line down one side. It opened and peeled back like a 'jacket', and the models came right out. I then reassembled the molds and strapped them tightly closed. Melted wax was poured inside, and the molds were rotated as the wax cooled and hardened so that the casting would be hollow. The molds were opened again, and the wax copies were removed. These pieces were then cast in bronze and bolted together. (The different colors were created by treating the metal with different chemicals after casting.) As you can see, the silicone picked up and replicated every detail, even the "hair" that was created by running a toothbrush over the clay.

Silicone caulk might be cheap, but it really can give you some great results!


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Pam :-)

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Wed Jul 15, 2015 5:58 am
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