Supplies I Used:
Urethane Mold
Challenge 90 Release
Fiberglass Resin w/catalyst
Cabosil
Chopped Fiber
Latex or Vinyl Gloves
Dust Mask or Respirator
Chip Brush
1- 32 oz. Mixing Tub
1- 3oz. Measuring Cup


Work in a well ventilated area with plastic sheeting or a protective cover on your working surface. Use a dust mask or respirator (highly recommended) as the fumes just aren't good for you to breathe. Wear latex or vinyl (if you are allergic to latex) gloves.


The mold I used is made of a Urethane Elastomer but you can put fiberglass into silicone or latex as well. I've used the fiberglass as an end product but you can use it to make molds or mold casings. It's great for big pieces because it is so durable yet lightweight.


I brushed a wax release into the mold first. You can use different wax releases, I used Challenge 90 which I find is the best for urethanes...and silicones. I brushed on a coat of release and let it dry.


In the 32oz tub I poured to the half way mark on the container fiberglass resin. So I started with about 16 oz of resin. You can use bigger batches. I find this is a good size and since I can layer fiberglass over the already cured fiberglass with no problem.


I add 10% of the catalyst. Ours is red but they come in different colors. Pigment is added so you can see when your resin and catalyst are thoroughly mixed. Some people use a little more catalyst than others, but be careful as too much can start a fire or burn you badly if it gets on your skin. Also, when purchasing ask what the percent is as some catalysts may be stronger than others. After mixing the catalyst into the resin I brush on a first coat. This way I'm sure I will get the best detail out of the mold.


The clock is ticking because I've already added the catalyst to the resin. I have about 30 minutes before it starts to set up. But I want the 2nd layer to be thick. I added about 5oz of cabosil, which I used the 3oz measuring cups for. You can add more or less cabosil depending on how thick you want your resin. Cabosil is a thickner, great for fiberglass as well as silicones, bloods, latex, urethanes and more.


Instead of using fiberglass matt I use chopped fiber. Chop fiber is pieces of fiberglass in little pellet form. Great stuff to work with. I add about 2 - 3oz cups of chop fiber to the cabosil/resin mix. You can add more or less depending on how you like it.


Mix it well. You will have a paste that you can brush into your mold.


Depending on the piece I sometimes make the 2nd layer of fiberglass mix a bit thinner, just to make sure I catch all the detail in the piece without getting air bubbles trapped between fiberglass layers.


And then I would add a 3rd layer of fiberglass mix making sure it is pretty thick. I know I'm not giving you exact measurements but a lot of the work we do in the Industry is really quite personal. Everyone does things a little different, but it all works.


Let the resin cure. You'll know, it will be rock hard. You may feel heat coming off of it while it is setting up. That's from the chemical reaction of the catalyst and resin. Remember, don't put too much catalyst in. I've seen it smoke and burn...have the water ready... Pull your piece. You'll have an end piece with great detail.


I paint my piece with spray paint. You can use just about any paint to finish. When I use fiberglass for mold or mold casings I leave a flange around the edges and drill holes so I can just use bolts to bolt my mold together...don't even need banding straps.







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