I have worked with fiberglass on boats, but the first time that I tried using fiberglass on an RC model, I made a terrible botch of the job. However, an article which appeared in the AMA magazine Model Aviation (August, 1996, page 48) described how to handle fiberglass with ease. It worked great for me. Many in the club may know how to use the technique or still have their old issues to refer to. In case you don’t fall into either category, here is a synopsis of Bill Anderson’s article:
I always seemed to have trouble cutting the fiberglass material without it developing rough or frayed edges (especially when attempting to cut on the bias). It was also difficult to get the material to lie down and stay on a model’s fuselage (especially over compound curves) while I tried to coat the fiberglass. The resin’s cure time caused problems when the pieces of fiberglass moved or lifted up. I usually ended up with too much resin, bubbles to work out, and a lot of frustration. What I came up with has made working with fiberglass easy.
You will need:
- a fiberglass cloth
- some large grocery-type bags
- a can of 3M77 Spray Adhesive
- a box of wax paper
- paper toweling
Preparing the Fiberglass Cloth
- Cut a piece of glass cloth that will be larger than the piece you finally need.
- Lay the cloth on the paper bag and get the weave straightened out.
- Spray the fiberglass cloth with a light coat of the 3M77.
- Tear off a piece of waxed paper that’s bigger than the piece of fiberglass cloth.
- Lay the waxed paper on top of the sprayed fiberglass cloth (shiny or waxed side down) and smooth the waxed paper with some light pressure from your hands. If you get wrinkles in the waxed paper, you can take it off and put on a new piece.
- Starting from a corner of the waxed paper, carefully pull the paper bag apart from the fiberglass which should stay adhered to the waxed paper. You now have self-adhesive fiberglass cloth with a wax-paper backing.
- You will be amazed at how easily this cloth can be cut. Using scissors or an X-Acto knife, you’ll be able to cut whatever size piece you need without frayed edges or loose threads.
Applying the Prepared Fiberglass
When you are ready to apply the fiberglass to your airplane, just peel the waxed paper and apply the cloth to the model in the desired location. Be careful not to let the cloth stick to itself. Smooth down the cloth with your fingers. If you get a wrinkle, or if the cloth didn’t go exactly where you wanted, just pull it back up and try again. The treated fiberglass can be applied over compound curves or overlaid with a second piece; once you’ve applied the cloth to the model, the cloth won’t move without intentional effort to reposition it.
Coating the Fiberglass with Resin
The model is now ready to coat with resin. Coating can be done right away, or you can wait a day or two - it won’t matter. The 3M77 doesn’t affect the resin: it will soak in and act like it normally does. Fiberglass can be positioned on several different parts of the model and then coated with resin in one operation. Excess resin is easily removed by wiping and dabbing with a piece of paper toweling. The fact that the fiberglass remains in place while you wipe means that the minimum amount of resin can be left on the plane. Leftover pieces of cloth still stuck to waxed paper can be kept and used a month later.