Hot Fuel Proof?

On 4/7/2004 6:00 PM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

The "Hot Fuel Proof" is an old designation used for indicating whether or not the paint was resistant to glo fuel residue - this was back in the days before mufflers to direct most of the residue away from the plane. A more accurate test would be for raw fuel.

To test your paint, put some "raw" fuel on the test panel and let it sit for 30 - 45 minutes (or a longer if you prefer) and then wipe it off. The reason I say 30 - 45 minutes is that is how long any spilled fuel/fuel residue will NORMALLY be on the plane before being cleaned off. MOST paints that say they are "fuel proof" are really just "fuel resistant". If you are not sure, give it a clear coat of water base poly, that is fuel resistant to 10% nitro. The only paints I am aware of that are "FUEL PROOF" are the type of automotive paint that is a paint/clear coat and epoxy paints.

FWIW - The Duro brand (11 oz can in the auto section of Wal-Mart, about $4.00) of silver is FUEL RESISTANT to raw 10% nitro fuel (Byron's) at least for 45 minutes. In addition it is almost an exact match for SolarTex silver.

Morgan makes a fuel called Omega that is already a synthetic/castor blend. If it's available in your area it would save the expense/hassle of buying and mixing the extra oil.

Carrell

Hot Fuel Proof! What does that really mean? I have a plane that is entirely sheeted in 1/32 balsa. I want to paint this plane in a sliver and Gold paint scheme. The paint I have is exterior enamel. Nowhere on the can does it say "Hot Fuel Proof". I painted a 3 X 6 piece of balsa with it for a test. Does "Hot Fuel Proof" mean that I can apply raw fuel to the paint without damaging the paint or the wood? Or should I test for "Hot Fuel Proof" by placing my 3 X 6 test piece into the exhaust of a running engine?

The fuel I use is, Morgan Fuel, 10% nitro. It says total synthetic on the label but I add 5 more percent of Cool Power brand Castor oil to each gallon. Why? Because my Irvine engines says to always use some Castor even with synthetic. So this is the fuel I will be using to test my paint. If the paint doesn't come off can I assume it is "Hot Fuel Proof"? How long should I leave the fuel on the paint? Days? Week?

The reason I use Morgan Cool Power is because that is what I can get the cheapest. I know someone who works at a hobby shop and they will pick it up for me and let me have it with their employee discount which is almost 30%. This hobby shop deals more in cars than planes and most of their fuel is for cars. So I take what I can get and I don?t think they have Omega. I got some RedMax that was a synthetic/Castor blend at another hobby shop but it cost me $4.00 more for a gallon. The Castor cost me $5.75 a quart but that will do 5 gallons of fuel. Plus I have the peace of mind that I am probably get at least 20% or more of lubricant in my fuel.

Thanks for the information. If I find some Omega 10% and if it is close to what I pay now I may try it.

Thanks for the information. I just painted my test piece this evening. So I am going to let it dry for at least 48 hours. Then I will test it just like you said with raw fuel.

"Hot fuel" is model glow fuel with nitromethane, as opposed to just alcohol/castor oil. It doesn't mean thermal heat, such as right out of the muffler.

Most enamels are not fuel proof and will bubble and deteriorate badly. Use a polyurethane or catalyzed acrylic instead.

If you are going to paint directly over bare balsa, be prepared for a very heavy finish with lots of cracks later on. A better bet would be to cover it with light silkspan before painting. Use clear polyurethane paint for adhesion.

Ted's reply is correct. It refers to the thermally hot exhaust from a

2 stroke engine which has quite a lot of unburned fuel coming out. Way back when, there were no mufflers, so the exhaust generally went right onto the wing on a profile model, or right down the fuselage if you were rich and could get a 'built-up' fuselage model.

David