Fuel proofing hard to reach ARF
 

ARFs are OK but why the heck don't the mfg's fuel proof the rear of the fire wall & tank compartment? Other than cost that is.
Need suggestions how I can do this. Also what can I use besides thinned epoxy or regular fuel proofing products from the hobby shop? Latex paint? Sanding sealer? Spray enamel? May have to get sloppy with it to reach all areas so it will need to be runny. Thanks.

Fuel proofing hard to reach ARF
 

I've been using an acid brush which I attach a 1/4 long dowl. This reaches down inside ok...but your right it's messy.

I use thinned epoxy and then just throw the brush away.

Fuel proofing hard to reach ARF
 

Ditto. Messy means it's fuelproof...

Fuel proofing hard to reach ARF
 

I have had good luck with spray cans of polyurathane. You can change the spray tips with other spray cans so you can use the small straws to reach in from the front through a motor mount screw hole or hole for fuel line.

Dru.

Fuel proofing hard to reach ARF
 

You can also put a good amount of the sealer you're using in there and then roll the plane around at various angles to move the puddle around. A dentists mirror is really handy for seeing where the wood is still dry. You can get them at harware stores.

Polyurethane is already at a good viscosity for this and is fuel proof.

After everywhere is wet, you can use paper towels in to sop up the extra.

Fuel proofing hard to reach ARF
 

It's a little more expensive, but you could use thin CA, and one of those "tip extentions". Just a thought.

Jetts

Fuel proofing hard to reach ARF
 

Unfortunately, CA is not raw fuel proof. Nitro dissolves it. I remember a tip in one of the magazines for getting CA off of tools: put the tool and some fuel in a plastic baggie. I also remember reading that some of the debonders out there are actually nitromethane.

Fuel proofing hard to reach ARF
 

Thanks to all that made suggestions. Think I will try the poly method. Can get to the fire wall OK and through the fire wall's hole for the fuel lines for the aft section. Thanks again. Ben

Fuel proofing hard to reach ARF
 

Thin slooooow epoxy with alcohol until it is very runny and thin. The alcohol evaporates and leaves a nice lightweight coating of epoxy.....

Ernie

Fuel proofing hard to reach ARF
 

I spray fuelproof paint (Lustrekote or similar) onto the firewall and into the fuel compartment. No straws or special nozzles. I figure that it covers around 90% of the surface area that might be exposed to fuel splatter, and that's good enough for me.