kirknik

I've heard of mixing epoxy and alcohol for fuel proofing say in an engine or fuel tank area.
What kind of alcohol?

vica6m5

My Feedback: (2)

Denatured alcohol works real well.

kirknik

Thanks......30min epoxy is ok I guess. How long wil it take to set?

TerrellFlyer

I've used all types of alcohol, they all work.I usually use 5 or 15 minute epoxy,if you want color,add cake coloring or a dye.

BillHarris

Better than alcohol: brush the 30-minute epoxy on and hit it with a heat gun. It "soaks" into the wood a lot better: you can see the wood bubble as it degasses and see the epoxy go onto the wood as it cools. The firewall, etc, has to be held horizontal since the warm epoxy is quite fluid. Another plus is that heating the exoxy will accelerate the cure.

--Bill

MinnFlyer

My Feedback: (4)

it will take longer to fully cure 24 - 72 hours depending on ratio, temp etc.

TerrellFlyer

yesterday at 4 pm,I mixed 50/50 blend,,more or less,using the swag method,added some blue cake coloring,70% rubbing alcohol,20 minute epoxy.8 am this morning the engine compartment was cured and now has an engine.

tiggerinmk

In the days of old, when knights were bold etc..

back in ol' Blighty you could buy pots of Humbrol 'Hot fuel proofer'


Alas, 20 years on in this supposedly advanced country, there is no available product for fuel proofing.

So how does this epoxy thing work?

Do you mix the epoxy and hardener as usual or just use the epoxy? Its kind of a bit thick and gooey to brush over a wide area....

Also, what is the "swag method"?

I'm not a newbie, I've built planes before, but this stuff is all gobbledegook to me......

pinball-RCU

I'm not sure what gave you that impression. You can buy "epoxy resin" in the quart size at Home Depot, and in smaller sizes from folks like Great Planes. It goes on like paint and is totally fuel proof. The Balsarite folks say that a few coats of the film formula is also fuel proof, although there may be issues getting the stuff. I think someone said that polyester resin (used a lot on boats) is fuel proof as well, and is much less expensive than epoxy. While many many people swear by the method of thinning epoxy, I never had much luck (just created a gooey mess), and vendors of epoxy generally recommend against it.

foxx

My Feedback: (2)

I get a little medicine cup and mix epoxy and its hardener just the ususal way, then add denatured alcohol to the mixer until it is thin enough to be painted on with a brush. Again make sure it thin enough to penetrate the wood. I have used this system of fuel proofing for over 20 years with great success

hauckf

Pinball: What is the stuff called that you get at Home Depot and what department is it in? I've used a two part epoxy called EnviroTech (or something like that) for both glassing over sheeting and fuelproofing. Works pretty well, but it cures quite slowly. Used to get it in the craft dept at Kmart (I think its intended to be used for decopage).

pinball-RCU

I think it actually says "epoxy resin" on the can, or maybe "epoxy finishing resin". It's not cheap (about $30 a quart, I think), and like all epoxy, it's relatively heavy, but I brush it on well. It comes in two cans, which you mix 50/50. It should be with the other glues, usually near the paint department, but it seems like glue is one of those things that's in different places in different Home Depots. It should be with the Goop, and Elmers, and cans of contact cement. If you find the polyester resin, which comes in a lot more sizes, with pictures of boats on it, you're in the right place. Another place to look, if you have one, is a boat store.

This stuff also cures slowly, basically 24 hours to harden. It's good for glassing (that's probably what it's made for).

tiggerinmk

Pinball,

Maybe you misunderstood my point slightly. Some 20 odd years ago when tissue and dope was the norm, you could buy a pot of 'Fuel Proofer'.

Now if you go into your local LHS and ask for fuel proofer, you will get a look like they've just seen an alien!

Having seen the posts here, it looks like I'll be popping into Lowes on the way home to get some 'denatured' or some other pure alcohol (it seems that my bottle of 70% rubbing alcohol won't be up to the job) to thin down some epoxy. I might look into the epoxy resin while I am there.

To my mind epoxy is glue, used for assembling parts not fuel proofing them. If the the epoxy vendors are against thinning epoxy then that really proves the point.

It seems that each branch of the hobby probably has its own ideas about what paint, adhesives, or other finishes might be fuel proof most likely brought on by experimentation as there seems to be no actual current product sold as fuel proofer.

Don't get me wrong, I really appreciate your help and advice, it just that it seems to me that there is an obvious market for a specific product for fuel proofing.

So, it looks like I'll be spreading glue over an area that doesn't need to be glued then giving it the once over with a spray of Lustrekote. Still seems like improvisation to me.......


You have a similar scenario over here with the rubber bands you use to hold wings on, but that's another story......

hauckf

Thanks pinball, I'll look for it. Regarding polyester resin, I've used it for both fuel proofing and for glassing. I think it was Bondo brand. Yes, it is fuelproof, and strong, but it is difficult to sand (gummy, loads up the paper) and stinks to high heaven. The one good thing about it is that monocoat sticks to it like crazy; not so epoxy.

foxx

My Feedback: (2)

Triggerrinv
improvisation is the name of the game. I think you want is a product to say fuel roofing on the box to make you happy no matter what is inside. Our Happy is full of common industrial product which have been repackaged and sold at many times higher price. Model Magic is good example which is nothing but Sears light plaster filler around $1.19 sold at hobby stores for over $5.00. There is more that one way to skin a cat.

tiggerinmk

Yup I agree improv is the name of the name, more so with some models than others.

I was just looking at a bottle of SIG Supercoat that I happened to have from a previous project. Supercoat is just a coloured butyrate dope. It says on the container that it is fuel proof, but not HOW fuel proof.

eg LustreKote does at least say that it resists up to 15% nitro.

That old Humbrol fuel proofer I was talking about was probably just a form of dope that you use as a top coat over colour dopes perhaps with added ingredients to protect the surface against high nitro fuel.

Dope as such, is not readily available in hobby shops as the majority of people now use iron on coverings. However, a liquid of a consistancy that is easy to paint with that is sold as resisting high nitro fuel would be preferable to many people over mixing glue and alcohol (even if the product is just a beefed up dope).

I bet if Top Flite started marketing LustreKote fuel proofer people would be rushing to the shops to buy it.

Meanwhile, on with the glue mixing.....

FlyingPilgrim

My Feedback: (26)

I've been using thinned epoxy for a few years now, and yes, regular rubbing alcohol works fine. (I believe it is the exact same Isopropyl) Available in different purety, usually 70% or 91%. $1.99 a quart at CVS. Mix the two part epoxy first, then add the alcohol a little at a time until you get the desired consistency.

foxx

My Feedback: (2)

hauckf
There are two type of polyester resin, they are called type I and type II. One is for laminating which leave a sticky surface for the next layer and the second type is finishing polyester resin which hardens like a rock and is very sand-able. You should use the right product for the right job. for more info go to:
http://www.aircraftspruce.com

tiggerinmk

Thanks for the info, turns out 70% isopropyl is what I had.

Based on earlier advice I bought a quart of denatured alcohol from Lowes on the way home. Cost $3.47.

Fuel proofing is all done and drying as I type....

I'll be posting piccies of my progress soon.

MinnFlyer

My Feedback: (4)

It certainly didn't hurt that you bought the denatured stuff, but the 70% isopropyl would have worked too. Go check... It should be dry by now

DLT

My Feedback: (48)

I use thin CA....quick and easy and the firewall is totally fuel proof. Have done it this way for years and never had any fuel soak in to the firewall.....just .02

RCaeroguy

My Feedback: (4)

swag - scientific wild ***** guess

firefighter

I usually mix up 5 minute epoxy, heat it up with your heat gun so it is thinner/runny, brush it on your firewall or desired area. Obviously the thinner it is the better it will penetrate in the wood. If I am doing an exposed firewall, I will cover it with saran wrap so I have a smooth finish. Then I go downstairs, mix up 1 part coke (12 oz) with 2 oz's of Jack Daniels, and I watch TV. This has been very succesful for me over the years. If for any reason you have more of the coke and jack daniels mix.....do not continue to build on your plane..STRANGE THING WILL HAPPEN!!! All measure utencils will be rendered useless as you will have convinced yourself that they are bothersome and time consuming. You will rely on your "years of building skills" and the old fashion way of measuring , close one eye and squwint with the other... Covering Jobs will be hideous as your thought process brings you to the realization that your plane will be "way high in the air and moving very fast, so who is possibly gonna see any imperfections" .

OHHH yes...servo/control set up. That is always good, so the rudder binds up a little when moving to the left...who turns left anyways....it moves fine to the right.....make more right turns...


tail wheel giving you problems.......leave it off, it used for 10 seconds when taxing and taking off, and 10 seconds while landing and taxiing. ON a 15 minute flight, that is absolutely not mission critical

I could go on and on, but none of us have ever done this, so it is pointless

tiggerinmk

Minnflyer,

Yup, I checked it last night, all dry now ready for a squirt of Lustrekote....

DLT,

When the LHS starts selling gallon jugs of CA I'll just get right in there and pour that stuff on.
Right now I've only got one little pot, and I'm sure I've got some fingers that need sticking together....

Firefighter,
I like your method, don't know why I didn't think of it, I've got all the required ingredients.... Must remember to keep the two seperate though, wouldn't want to drink the epoxy and paint the plane with coke

Funny you should mention control set up. On the Zephyr I'm doing, the rudder is held on with some sort of sticky tape on the left side with the rudder and fin bevelled to allow movement.
This gives me about 20 deg of right rudder and 180 deg of left rudder... :spinnyeye

Look like I'll be practising my left turns then

I'm sure it will be interesting to fly when its finished.....thanks for all your help guys....

hauckf

Firefighter: I am appalled that you would suggest that anyone should work on an airplane, and then while waiting for the epoxy to cure, drink Jack Daniels and Coke. This is not the kind of advice that should be given on this type of forum. That fine Tennessee sippin' whiskey should be enjoyed straight up or on the rocks, as I am doing as I type this, not mixed with Coke!