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Fiberglass Part Making [by: Halloweenking]
Hotrodders Bulletin Board: Knowledge Base: Body-Exterior: Articles

When making fiberglass or any other composite material body piece or custom part, the most important ingredients are time and patience. Fiberglass and other composite materials (such as carbon fiber) require four things: cloth or weave, resin, separating agent, and a mold.

Fiberglass has long been used in the automotive industry, both in the production and customizing world. The first full American production car to utilize a fiberglass composite body was the Chevrolet Corvette, in 1954. Composite materials are used mostly because they are lighter weight and they don't sacrifice structural stability.

Within recent years, carbon fiber has become the latest "must have", mostly because of its distinctive look -- its extreme structural integrity and light weight are just an added bonus. Carbon fiber is much more attractive than fiberglass, but in most parts, such as body panels, both substances are used in a sandwiching process. Carbon fiber is also superior to fiberglass, as well as metal, in its strength to weight ratio.

Below is a step-by-step on how to accomplish the task of body panel construction. The process described below can be applied to any part or panel you wish to construct. For simplicity of explanation, a hood was chosen.

Making an OEM reproduction of an existing hood is as simple as 1-2-3. The easiest way to do this would be to remove your hood, strip off all paint, and smooth the hood to perfection with some minor bodywork and a coat of smoothly sanded primer. If you do not smooth the hood before making the mold, any imperfections in the mold will also be in your part. In the case of a carbon fiber hood, that simply isn't acceptable. After you have smoothed the panel, you will need to apply the separating agent to the surface you wish to replicate, in this case the top and rear frame of the hood. A good separating agent can be purchased at any composite material store. For smaller, less cosmetic parts, any type of wax can be used. After you have applied the separating agent, it's time to start making the mold.

You will need:
  1. Fiberglass weave or cloth pre-cut at least 3" larger on each side of the hood (should hang over each side), laid out for quick retrieval. Carbon fiber also, if you desire a carbon fiber part.
  2. A paint roller with a section of PVC pipe over the roller, snugly fit and coated with separating agent or wax.
  3. Plastic filler spreaders
  4. Natural bristle 3-5" paintbrushes with bristles held by adhesive, not crimped.
  5. 4 small plastic pails
  6. Rubber gloves
  7. Smock
  8. Old clothes
  9. Extra set of helping hands
  10. Gel coat
  11. Spray gun

With a mold, the basic idea is to replicate as best as possible and as smooth as possible.



Now that you have a female mold from the male part you wish to replicate, it's time to make the part.
This process can be used in any part making from OEM replication to custom parts. Custom parts will require a male piece to make a female mold. A male piece can be made from anything, foam, wood, plaster of paris, plastic filler or even candle wax or any combination therein. Foam can be used, but due to the chemical makeup of the resin, it must be covered in a few layers of either plastic filler or regular latex house primer, sanded smoothly, and of course before any application of resin you must apply a separating agent.

Always use good quality resins and cloth or weave from a reputable dealer. The quality of the supplies will result in the quality of your product.