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KitMaker Network

Mold Making and Resin Casting

To start, we need to make a clay bed under our subject for support. You want these supports, or "pillars" to be 1/2 to 1 inch high, depending on the size of the piece to be molded. (larger pieces require more clay for support as more silicone, thus more weight, will be on top) (Fig 10) The last thing you want is for your clay bed to collapse once your silicone is poured) By suspending your prototype, you are also allowing air bubbles to rise away from it more easily to what will eventually be the outside of the mold.

Next, use similar sized pieces of clay to build your bed outwards (Fig 11). Remember that we want about a half an inch space between the sides of our box walls and the prototype.

Now that your part is suspended from your base, use fairly flat pieces of clay and start sealing your part at a right angle to the clay. Work a side at a time, sealing as you go. I just use my finger here to "rough in " the prototype (Fig 11a).

Use a flat scraping tool (I use a bent, flat file, sanded smooth and with rounded corners) to be sure that your clay bed is sealed against your prototype (Fig 12). Try to be sure that you seal the clay at right angles. In other words, try not to have your clay at an up or down slope.

Once your clay is sealed all the way around to the prototype, it is time to clean the part of any bits of clay that will affect the mold. Use your scraping tool to remove what you can, and then use a brush dipped in rubbing alcohol to clean the rest (Fig 13). Rubbing alcohol will dissolve the clay residue left on your part to insure that none of the detail is lost. Remember, your silicone will pick up every bit of detail including bits of clay!

Use a hacksaw blade to cut each side square as shown in Fig 14.
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