I just started putting together a new ARF plane. Is there a need to fuelproof the firewall and fueltank compartment? The instructions say nothing about it and the wood looks untreated to me. If there is a need what do you use? Epoxy and and paintbrush? HELP!!

Thanks!

If you can get in there, it is a good idea to fuel proof. Epoxy thinned with denatured alcohol is probably one of the more popular methods. Use an 'acid' brush, and thin to consistency of water.

denatured alcohol....I have 91% isopropyl alocohol. Will that work?

It will, but the epoxy will take quite a while to harden. Iso alcohol as a thinner makes the epoxy 'rubbery'. It will take 1-2 weeks for it to harden fully, but it will be set up enough to fly in a day or two.

Yes, you should definitely fuel proof the engine area and tank compartment if you can get to it. Without fuel proofing fuel and oil will soak the wood in that area and eventually weaken the wood. Thinning as Deadeye instructed is good, but I prefer to apply the epoxy without thinning if possible. If you thin the epoxy too much it will never completely harden and will stay soft. To apply without thinning I mix 30 minute epoxy, use a stick (or your epoxy brush) to apply a good "blob" of epoxy on the area to cover, and then heat it with you heat gun. This will thin it out to where you can spread it out with the epoxy brush. Heating the epoxy will shorten the cure time of the epoxy, so that is why you want to use 30 minute epoxy, if you use 5 minute it will set before you have a chance to spread it out. Using this method will allow you to put a thin coat down that will protect you wood.

I hope this helps.

Ken

A couple of other options for fuel proofing:

1. Thin the epoxy with acetone (about 10% by volume ). It will take several days to dry though.

2. Use clear fuel proof dope (Aerogloss or similar ).

FWIW - I normally use thinned epoxy on the firewall and in the fuel tank compartment. Any other exposed areas I use clear dope (push rod exits, aileron hatchs, etc. )