I am new at this and I have a p-51 hangar 9 trainer and I am gonna take the motor out so I can put some blue loctite on the engine mounting bolts and while I am at that I would also like to fuel proof the the engine mounting area, what does a
person use to do this.

My Hanger 9 twist was already fuel proofed, but you can use CA or epoxy to fuel proof (correct me if i'm wrong)

I would think the manufactuer would have already did this,but I always thin 30 min epoxy with rubbing alcohol and brush it on.

or you can use clear dope,be sure to have a well ventilated area if you do.

I agree to use epoxy to fuelproof and area, but I disagree with thinning it with alcohol. The reason why I say that it that it's possible to put too much alcohol in the epoxy and you will wind up with a mixture that will never cure properly. Instead of alcohol use heat to thin the epoxy. Start by mixing up a batch of 30-minute epoxy and then using a disposable epoxy brush put a small "blob" of epoxy where you want to start. Hit that blob with your heat gun to thin it out. It will thin out almost the consitency of water which you can then "paint" the area you are fuelproofing. Also by doing this is spreads out the epoxy so that it doesn't add additional weight to the plane.

Also advised against doing it using CA to fuelproof. That is just going to make a mess and add a lot of extra weight.

Ken

The alternative to thinning epoxy is to use epoxy that is already thin.
Finish epoxy sold at hobby shops is thin as are higher end epoxies like West Sytems.

i like spray clear polyurathane for in the tank area and in the under wing area also. u can spray a little into a dixie cup to brush on the firewall.

I use Polyurethane or, more often, epoxy mixed with alcohol.

The trick to using the epoxy is to add just a few drops of alcohol and mix - repeat if necessary until it's just thin enough to "Paint" with

To avoid the problem which RCKen stated, use hardware store Denatured Alcohol, or better yet Acetone.

Mix up 30 min epoxy WELL, then add about 1/3 Alcohol or Acetone to thin it down a bit. Mix it again WELL.

Since you are applying a thing layer to the rather large evaporative surface ( and this is not meant to bear a load ) the more slightly diluted mix tends does tend to dry fairly well.


Note that some Epoxies now come mixed with some form of "binder", probably in an attempt to lower the manufacturer's cost.

The Great Planes Epoxy is the most egregious of these. The resin has a "gritty" feel or texture to it, on every bottle I've opened.

Strangely the Tower Hobbies epoxy ( GP and TH epoxies are both sold by Tower ) does not have this problem.

The GP epoxy makes a very poor fuel proofer thanks to the added substances. It dries poorly when mixed with 50% alcohol.

The TH and other similiar mixes seem to fare MUCH better.

Ive used 30 minute epoxy thinned with just a drop of acetone(home depot). the acetone thins the epoxy out really well and easy to apply with a small brush. Never had an issue.

If you are going to thin epoxy there are a couple of things you need to be aware of.

1. Rubbing/Isoprophyl alcohol contains water. Use DENATURED alcohol or acetone to thin.

2. Do not thin more than 10% BY VOLUME. More than 10% and you have a very high probability of the epoxy not curing properly (or curing at all ).

3. Heat (via a heat gun ) is your best bet for thinning the epoxy. It is safe and will thin the epoxy very nicely.

FWIW - I have read mixed reviews on using CA for fuel proofing. SOME people say that the nitro in the fuel will weaken/dissolve the CA. Water base polyurethane (MinWax Polycrylic ) is fuel RESISTANT, oil base polyurethane is fuel proof. If you do not want to use epoxy for fuel proofing, use clear FUEL PROOF DOPE (2 coats ) or Ultracote clear or Lustercrap clear.

Arrgh!

YES corrected!!!! Thanks.

That's what I should have said!

Denatured Alcohol is what you purchase at a hardware store.


I've never had problems all the way up to 30-40%, especially for this use, namely fuel proofing.

However better to err on the side of caution.

It's a bit harder to "stretch" the epoxy this way. Not that it doesn't work.

I normally fuelproof the firewall area and just behind it with the strongest epoxy mix. Then use the thinner mix ( 30% ) to do all of the reachable wood surfaces within the fuselage that I am not otherwise re-inforcing.

I use 90% rubbing alcohol and have never had an issue with the epoxy hardening.Sometimes it takes longer than others,but it has never failed me.The point about it containg water is something I didnt realize.i will give the denatured stuff a try next time.

egregious?

There's a $5 word if ever I heard one

Hey Minnflyer I can't find that word in my thesaurus. Must be a $10 word ya think.

Or you need a better thesaurus

(What's another word for thesaurus?)

Try "Dictionary."