cool pool

Hi All,
I bought a used Hangar 9 Alpha 40 and noticed that one forward side of the wood near the muffler is starting to get fuel soaked. What is the best way to seal the wood for the whole engine bay area including the fire wall?
I was thinking on using flat black enamel paint and then put on a sealer.
Any thoughts ?
Thanks in advance.
Wayne

DMcQuinn

My Feedback: (13)

Almost any enamel based paint will work OK. Many use regular epoxy glue (like the 2-hour kind), but thinned a little bit with alcohol. I think this is a little more fuel-proof than any paint. It also may stick better on the areas that have already gotten oil on them.

jetmech05

i use 8hr epoxy thinned as much as 50% with alcohol. i dont think id use enamel paint at all
have fun

piper_chuck

My Feedback: (12)

Epoxy is often used. It can be thinned with a SMALL amount of alcohol (denatured, not the cheap drug store kind). Heat will also thin epoxy and doesn't risk making it cure softer. Personally I use a product called BalsaRite. It's designed to help covering stick to wood, but it's also fuel proof.

wtb3886

Greetings From South Carolina Cool Pool Wayne :-)

I bought a used Hangar 9 Alpha 40 and noticed that one forward side of the wood
near the muffler is starting to get fuel soaked.

1st thing to do is remove the covering around this area and use K9 spot remover
something that removes moisture, let this dry & remove the moisture.

What is the best way to seal the wood for the whole engine bay area including the fire wall?

I use epoxie thinned with a little alcohol to coat the entire engine area to make it
fuel proof.

We want to be careful about the amount of weight that we add because of balance in
this area.

Tommy

2slow2matter

My Feedback: (1)

Agree with the above--before you seal anything, you need to get as much of that oil out as you can. Pull the covering back a little, and see how far it's soaked. Use the K9 if you can find it, or just use a heat gun on the area. The oil will come to the top, and you can literally wipe it off. Repeat until the wood is dry. Another way is corn starch mixed with alcohol. Brush on, wipe off when dry. Will soak the oil out of the wood. Will take several applications, though! Once dry, then seal it off. Use epoxy--30 min will do fine. Blob some on, and hit it with a heat gun. It will thin immediately, and you can brush it all around. remember, though, when using this method, it will cure much faster, so don't use anything less than 30 minute! Works like a charm...

micsrcfn

Hi All,

I believe you all are referring to "K2R" Spot remover?


Mic

piper_chuck

My Feedback: (12)

Probably, that K9 stuff is a dog.

elenasgrumpy

My Feedback: (4)

What about good ol hot fuel-proof clear dope, isn't that still an effective way to fuel-proof? I was planing on using clear dope for all the areas behind the firewall, going a little heavier in the fuel tank bay itself, & then using the heated epoxy method on the firewall for added strength & protection. Is this idea going to give me adequit protection or do I need to use epoxy for all of it? I'm trying to keep the weight down a little up front. I'll be placing the servos for the tail surfaces in the back of the fuselage as well. I'm hanging a Saito 100 on a .60 - .90 size plane and don't wanna turn it into an epoxy brick! Please let me know if I'm on the right track, if you think this won't be sufficient, I want to know that too. Thanks guys.


Mark

2slow2matter

My Feedback: (1)

OH yes, I'm braindead--just repeating what I saw. We can't get the KR2 stuff here anyway, so I have to resort to home-brews. At least, I've never seen it on the shelf...

I guess I could have my K9 come and try to lick the oil out He might like it!

piper_chuck

My Feedback: (12)

If it's castor based, you should plan to keep him outside for a few days after! [X(]

oldtyme

Recently I have been using Pactra or Aerogloss or whatever it is called today.......fuel proofer followed by a several coats of fuel proof clear. I still have some of the environmentally prohibited K&B Epoxy paint and I occasionally use that. Thinned epoxy is also very good.

Andy

elenasgrumpy

My Feedback: (4)

rcandy. Yes that is what I'm planning on using. Aerogloss clear hot fuel-proof dope for everything except the firewall where I intend to use epoxy thinned by heat not by alcohol. I was told by the LHS new "know it all" that they just hired, that denatured alcohol would break down epoxy alltogether, but apparently that's not the case according to piper chuck. I think I preferr to heat it up though so I don't weaken it at all.

I wasn't putting too much stock in anything this guy had to say anyway, since you can't name a Hobby Shop within 100 miles of here that he hasn't worked at & had something bad to say about everyone of them, makes think maybe he's the problem & not the Hobby Shops![X(]


Mark

Rodney

Thining epoxy with alchohol can lead to problems and entirely unecessary. Just use 30 minute or longer cure time epoxy and put it on as thin as you can. Usually a stiff bristled dissposable brush works well. After putting the epoxy on the area, heat it gently with your heat gun. It will flow out very nicely and wick into all the minor crevices and open grain. The heat will also speed up the cure. Not only will this fuel proof the area, it will strengthen the bond between firewall and fuselage which is often needed in some of the ARFs. Using alchohol to thin epoxy will sooner or later leave you with an uncureable rubbery sticky mess that will be very difficult to clean up or repair. This is because alchohol will absorb water (and worst of all is the medicinal alchohol you get at the local pharmacy which already has a high water content) which gets trapped and prevents the chemical curring of the epoxy. If you must use alchohol (some do and often get away with it) be sure it is fresh denatured purchased at the local paint or hardware store.

Lowlevlflyer

My Feedback: (3)

Well, maybe I am the exception to the rule, but I have used the plain old drug store medicinal alcohol to thin 30 minute epoxy for fuel proofing the firewalls on four different airplanes now, and I have not had a problem with it yet. It cures, sets up hard, and has NEVER made a rubbery mess yet. I wasnt aware I was supposed to be using only denatured stuff. It may not be the right stuff, but the drug store stuff will work though, I've got four fuel proofed firewalls to prove it.

da Rock

You know, lots of people have alcohol thinned epoxy on their firewalls. And the epoxy is cured. Or at least it seems to be cured. And it seems to be strong.

But truth is, the epoxy would have been lots stronger if it hadn't been thinned. And drugstore alcohol is what 70% alcohol, or if you spend another quarter, it'll be 90-something% alcohol. So what is the other percentage? And is it left behind when some of the alcohol evaporates? But so what....

If it seems to be strong enough to those people, good for them. One thing for sure, is that epoxy WILL be 100% as heavy as if it hadn't trapped whatever alcohol and "the other stuff" when it "cured" and whatever it trapped will be 100% as heavy as it was in the drugstore bottle.

This is another Ford vs Chevy argument, sort of. Really is more of a Mercedes vs Skoda argument however.

da Rock

As for the idea that everyone ought to be thinning epoxy only with denatured alcohol.... chuckle chuckle.....

Yeah right.... or actually..... no, not even denatured or denuded or detuned or any kind.

Truth is, you can thin it with water. The proof is given by the guys using drug store water, the 30% pure stuff that has 70% isopropyl in it. chuckle.... ok ok......

There is another group of epoxy thinners that uses something else. I think it's acetone. And it works too.

piper_chuck

My Feedback: (12)

Go ahead, thin it with water and see what happens. I suspect you won't be chuckling anymore. Yes, Acetone is also acceptable for thinning epoxy. The downside to adding acetone is it can cause the epoxy to cure with a dark brown color.

flyinrog

My Feedback: (1)

I use 5 minute epoxy..no thinning,, I have tried thinning it with alcohol but I got the mess,most of my stuff is 1/2a and have small areas to cover which is why I dont bother thinning it,I dont believe there is any weight issue either....Rog

Lowlevlflyer

My Feedback: (3)

Lowlevlflyer

My Feedback: (3)

Yeah, there is a MAJOR weight issue there... it might cause me to have to re-balance all the aircraft I have used this sorry alcohol thinned stuff on... As far as strength is concerned, do you mind telling me exactly what strength has to do with using epoxy to FUEL PROOF? It's not having to support anything or hold anything together, so I fail to see your point, if you had one. I've had alcohol thinned epoxy on a couple my aircraft for way over a year, and nothing has gotten through it, and it's still plenty strong.

piper_chuck

My Feedback: (12)

Rog, you better put those things on a scale, it's probably doubling their weight!

BTW, I hope you're getting a bit of time off work to enjoy some of this great weather we've been having. I got out to the field last Sunday but only got in 3 flights. There were at least 25 people at the field and having 1 of 5 or 6 planes in the air is just not my idea of a good time. The only bright spot is I was absolutely nailing my landings. The owner of the local hobby shop was watching my first one and told me I should quit for the day because it couldn't get any better.

2slow2matter

My Feedback: (1)

There is absolutely nothing wrong with using drug store alcohol to thin epoxy. As stated before, we aren't doing it for strenght, anyway. I also have 9 airplanes in my hanger, all of which (except one) have fuel proofing using the 90% isopropanol thinned epoxy method. No problems at all, and I don't suspect that I'll start having trouble now that I've read this thread. Some people like to over analyze stuff too much. The one plane that wasn't thinned with epoxy was thinned with heat--a method I learned from here on RCU. I must say, heat will make it every bit as thin as alcohol will, so from now on, I think that will be my method of choice--except for those hard to reach areas like fuel tank compartments in arfs, where you need it to be thinned before it hits the wood.


However, if you want to use alcohol, go ahead. You aren't going to hurt anything. Rubbery messes occur when the epoxy isn't mixed properly (not enough hardner, etc.), not because it was thinned. Alcohol may increase cure time, but will not prevent curing. I also fail to believe the alcohol gets trapped. With the heat generated by curing, I would imagine that most, if not all, of that alcohol evaporates. And the water? How much water are we possibly talking about? Especially with 90% stuff...

da Rock

I should have made it more obvious........ chuckle

The drug store isopropyl alcohol is only 70% isopropyl alcohol. What do you guess you're thinning with when you use it? So you're actually already thinning with water. And therein lies the answer..........

chuckle.....

I said that you can thin with water, and darn if you can't. You could thin with mud if you wanted to. Or motor oil. chuckle.... (but I wouldn't if I were you) If you're smart enough, it'll be obvious to you whether or not you should thin with water or mud and whether or not it'll make the epoxy stronger. But to save misunderstanding, don't thin with water or things that have water in them unless the strength of your epoxy isn't really important.

None of us are setup to do a quality test of the resulting strength of our epoxy, nor do any of us do any kind of test other than maybe a crash test later. Sure, some look at and touch the epoxy later on after application. But painting epoxy on a firewall isn't exactly an application that requires all the strength of the epoxy. And everybody forgets that whatever is trapped by the cured epoxy is adding weight.

Do yourself a favor and do a little test. Mix up a batch of epoxy in a little cup. Weigh it. Thin it with whatever you wish. Weigh it right away. Let it cure. Weigh it again.

Do another little test. Mix up some epoxy. Spread some of it on a balsa sheet. Now thin the rest with whatever you wish. Spread it on the other end of that balsa sheet. Let them cure. Now break the sheet where the two epoxy spreads are.

It's amazing how simple and easy some questions are answered for ourselves.

piper_chuck

My Feedback: (12)

Guess what, 70% is NOT the only grade of drug store isopropyl. chuckle...
Sure, one can thin it with whatever they please. However, if they want it to cure, it's best to stick to things that have been proven to work.
Even easier than reinventing the wheel, go do some searches online. West Systems IS equipped to do the required testing. They've concluded that diluting epoxy weakens it and can cause other issues. Their tests show that even a small amount such as 5% produces measureable changes. Even though the application being discussed does not require significant strength, it's still important to meantion so someone who doesn't know any better does not decide to dilute epoxy for some other application, such as wing or stab joints. Think this won't happen? Think again.

This is a beginner's forum. It's important to provide accurate information because people come here to learn. Belittling people who provide this information, making light of it, or making off the wall suggestions does nobody any good.

Edit: for those interested in learning more about this subject, I've found the following article to be helpful: http://www.westsystem.com/ewmag/14/ThinningEpoxy.html