Hi everybody.

i am almost done building a star cruieser from herr engineering. I got a norvel .074 for it. It is going to be first time for me to have throttle control. So im exited.

What do you do to fuelproof the firewall. Last time when i was building my cub i covered the firewall with 5 min epoxy. It worked well for a while but by time as i ran the engine the epoxy changed to a brown colored soft stuff. Looked like it was burnt or something.

Thanks
Engin Cansiz

Epoxy should be fine if mixed right and cures properly... I like to use just plain old clear polyurathane.

Polyurethane paint, balsarite, finishing epoxy...............take your pick

I like to mix up some 5min epoxy thinned out with alcohol. About 50/50 mix and then brush it on. It will still yellow a little, but is 100% fuelproof and light. If you want a clear finish for looks, a clear dope like balsarite will also work. Be careful when using non-model brand products like minwax. Not all polyu's are equal. Clear lacquer is fuelproof, but will yellow with time.

I use thin CA and spread it around with my finger wrapped in a piece of wax paper.Let it air dry and you will get a smooth clear finish.Simple and works well.Chris

I use thinned epoxy like PTUlmer said - except that I put a drop of food coloring in the two-part mix for two reasons; one is (Hooray, ctrl-z works! I just hit escape too many times and my words came back like magic) that it helps make sure that you have mixed it thoroughly (just try it, you'll see). The other resaon is to provide color up from that comes close to whatever I was going to cover/paint the fuselage with. You can always find four color packages in the cake mix part of the grocery store (red, blue, green, yellow). At Easter time you might be able to find more color selection. The third reason is that you avois the yellowing effect if you use a dark shade. I have been doing this for at least 20 years. It does not weaken the epoxy in fact I would argue that it would minimize the effects of ultra-violet rays and moon beams.

why not cover the fire wall with $cote...i do it all the time...

john

Thinned slow drying epoxy. And I like the food coloring idea. I hope I can remember it long enough to try it.

I use polyurathane on the inside also in case of a fuel leak.

In areas in the fuse where its hard to reach, I normally spray clear Lustercoat

Chris,

You might want to rethink that. Nitromethane is a debonder for CA.

George

thanks everyone.

What i did for my old plane was i put a layer of medium ca then i covered with epoxy. and there is no more epoxy left. it turned dark brown and just came off from the firewall.maybe i should apply the epoxy directly to the wood??


and also where can i find Polyurethane??

I use CA for fuelproofing the firewall and I've never had a problem.

Well, if both you and Chris use it successfully, I guess you can't argue with success.

Think I'll still avoid it though.

George

It may be that we never get raw fuel on the firewall. I've found that epoxy goes mushy after a few years; maybe due to quality or type used.

After you brush the epoxy on you can hit it with the heat gun a little and it will soak into the wood. Never had any trouble with an airplane lasting longer than the firewall...

Mixing alcohol with epoxy seem to interfere with the crosslinking and results in "rubbery" epoxy. I would recommend using finishing epoxy instead. Easy to brush on, and cures hard.

I bought some of this after i searched alittle bit here on rcu. Is this the right stuff???

any experiences with it??

That should work

May I suggest a test with the Minwax....
Dip a popsicle stick in, get a good coat on, let it dry for 2 days then put raw fuel of the octane you intend to use on it.

Three to four coats of balsaright, then cover with your favorite covering.

Another option.

Darren

mr leffe

thats what i am doing right now.

i put 2 layers on a piece of wood and let it dry. on the instructions it says they recommend 3 layers and i will do so. it is drying hard and very glossy. after the third layer i will soak the wood in raw fuel and will see.

Thanks

How did your Minwax experiment go?

Yeah sorry forgot to tell about that.

I think it worked very well. I did 3 layers on a poece of wood and spilled some raw fuel on it, waited overnight then when i wiped it off it was still almost as glossy as other parts. I used it for fuelproofing my firewall. Raw fuel hardly gets on the firewall anyways. Flew my plane today it hasnt gone yellow yet but it might be too early to tell that.