We are making a supermilage car with a fiberglass shell and we have access to styrofoam to make our plug. I would like to use polyester resin because it is much cheaper than epoxy, but polyester melts styrofoam. Would we be able to coat the styrofoam with plaster of paris or something else to keep the resin from melting the styrofoam?Also, to anyone who knows anything about fiberglass, how much resin are we going to need? (The body is roughly going to be about 6 feet long, 2 feet tall, and 2 feet wide) I am guessing it will be about a gallon.
Quite a task youve chosen for yourself. Although the plaster will prevent the styrofoam from melting. The plaster is very fracture critical. In otherwords.dont bump it or it will dislodge the plaster and you have to rely upon the plaster shell to remain solid during the application. After applying the first coat of matting and resin. I would fill and shape with fibreglass filler as found at your bodyshop supply house. Just remember to keep the layer of plaster at its thinnest possible Mil. Its just a sealer. Hope this helps.
No offense, but at this point in development CHEAP may not be the better way to research success and effect. I will offer a suggestion. I use this product all the time for Theatrical set building, and while you don't detail the need for Styro, beyond PLUG, as opposed to taking the time to make a mold, and do a fiberglass unit as well, FOAMCOTE/FOMECOAT/ or whatever, I don't have a jug in front of me, IS a Stryo coating that essentially looks like White Elmers Glue. I buy it in gallon jugs. For styro props and scenery/ shapes I use it with Cheese cloth, paint it on with throw away brushes, though initially it is water washable, let it dry, and I can spray, brush, pour, anything over it, with no adverse effect on the styro. I also once worked for a defense contractor and used Fiberglass all the time for models/prototypes, but had to build molds first. What is your framework? Just the styro? Is this a prototype for some production CAR, or some soap box derby deal? No offense. I suspect you should buy the Fiberglass mesh in roll stock to trim later, no less than 4 ft wide. I further suspect, depending on method of application, you'll probably need a gallon of catalyst alone, and perhaps 4 gallons, Plus/Minus, or resin. As one answer states the strength is based in the fabric, and the resin properly applied should SOAK the cloth. Steven Wolf Just my two sense
Plaster of Paris sounds like a good idea. One thing I do know is to make sure you add the cloth when you do the fiberglass. The strength comes from the cloth fiber. I know from building boats that wood is stronger per pound than fiberglass So you might want to think about using some wood The down side of wood is it's not as durable as fiberglass because it can rot when wet. Also resin is heavy so the more coats you put on it can get very heavy fast.
