Types of liquid finishes used to apply fiberglass cloth
There are several liquids that are appropriate for applying glass
cloth. I've used some, but not all of them. After trying a few
different things, I found something that I like so I have no desire to try
anything else. That's pretty much how all of model building goes.
There are no set rules, it's just finding the methods and techniques that
you do best.
Epoxy resin of at least two types can be used. Slow drying
(30 minute minimum) epoxy glue is commonly used to apply glass cloth,
but it is thick and does not penetrate the cloth well. Regular epoxy
glue is fine for things like glassing the center of a wing or similar
reinforcements, but for large surfaces it just doesn't work as well as other
types of resin.
Epoxy Finishing Resin (normally just called Finishing Resin or
Laminating Resin) is designed specifically to apply composite cloths such as fiberglass and
carbon fiber. It has a thin consistency and a slow drying time.
It penetrates and saturates the cloth quickly and spreads easily.
I used 1 hour resin for the work done in this series of articles.
This is the first time I used resin that cures this slowly and I would not use it again.
1 hour epoxy cures so
slowly that too much of it soaked into the wood. This resulted in a
lot more filler being necessary to fill the weave of the cloth. More
filler = more weight. I have always used 30 minute resin in the past and
good results with it.
The bottom line is that I recommend that you use 30 minute Finishing
Resin for applying glass cloth.
Fiberglass resin is polyester resin. It is a
two-part resin having a catalyst that I believe is peroxide based. The
more drops of the catalyst added to the resin, the faster it cures.
Note that polyester resin does not cure properly over epoxy.
Therefore, if you make things like fillets using epoxy and micro-balloons,
you may run into problems if you attempt to use polyester resin over it.
Epoxy can be used over polyester, but there may be adhesion problems.
It's best to stick with one or the other and not try to use them both.
I do not use fiberglass resin because it smells horrible, causes bad
rashes on my skin and makes me itch all over. Polyester resin dries
very hard and will sand better than epoxy resins sooner. By that I
mean epoxy resins take longer to achieve the same hardness. I don't
mind waiting, so I have not had a problem using epoxies, but some people
complain that epoxies do not sand well which indicates to me they are trying
to sand too soon.
In addition to the above methods that I have used, other people have
claimed to use the following to apply glass cloth. I have not used any
of the following, so I can't speak from experience.
Epoxy Paint (clear)
Polyurethane Paint (water or solvent-based clear)
Airplane Dope (clear)
Some people will recommend that you use
cyanoacrylate to apply glass cloth. I think
using CA is a really bad idea. First, the fumes created are enough to
knock out a stable full of horses. Second, it is expensive and has a
working time of zero seconds once it is applied. Lastly, you have
absolutely no control of where it goes. It simple gets poured on and
you hope for the best.
Resin and Fiberglass cloth are available from a variety of sources.
I purchase mine from