Making Fiberglass Molds With Clay - Vintage Mustang Forums

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post #1 of 5 (permalink) Old 03-14-2002, 07:15 PM
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Sorry for repeating this again. Its just that I would really like to use clay to make the apron because its easy to work with and I was hoping to get something that is soft and dries hard. I was wandering for making a mold for my fiberglass front apron. Can I use clay or something. Because I was reading the Mustang Monthly article on Eleanor and they used clay for there design and i was wandering if I could do that because it would be real easy to work with and see what Im trying to do. So I any help would be greatful. Thanks Guys. Once again sorry for repeating.

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post #2 of 5 (permalink) Old 03-14-2002, 07:25 PM
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Absolutely, I work at the Ford Desing Center and we use clay all day long. You can use modeling clay. Don't forget to spray the clay with a parting agent before you layup the fiberglass.

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post #3 of 5 (permalink) Old 03-14-2002, 07:50 PM
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This would be a 2 part process. Create the body part that you want. Smooth it and make it look like you want. Apply the releasing agent, apply your fiberglass. Now you have a "negative" mold. You apply the releasing agent to the "negative" mold and apply your fiberglass for the body part you want.

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post #4 of 5 (permalink) Old 03-14-2002, 10:58 PM
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The way I have always seen this done is that you model the thing in clay. You don't have to make a huge clay lump. You could model the clay onto an existing valance with the part cut out that you want to be open. Once you have the clay shape the way you want it you then make a mold of the clay thing using plaster of paris. When the plaster of paris dries you remove it from your clay model and you then have a mold you can lay down flat. You may have to touch up your mold in a few spots. You lay your fiberglass into the plaster of paris mold which gives you a reproduction of your original clay shape. I'm not sure what you put on the inside of the plaster of paris mold to keep the fiberglass from sticking to it.

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post #5 of 5 (permalink) Old 03-15-2002, 09:06 AM
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What we used to use when we made clay models is first build a subframe using wood and the dense blue styrofoam and coat that with Gesso. The clay was kept at a constant temperature which was almost too hot to touch. I can't remember the actual temperature. Then placing the warm clay on the gesso (art supply store) mold working it to a smooth finish was the technique we would use. The clay was usually an inch or 2 thick.
I'm not sure what you should use as a parting agent but I think a floor wax paste would work.

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