fuel proofing

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17 July 2012 at 05:46 #35300
captainslog
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@captainslog
I have just sprayed the inside of a large hull with " appliance white " halfords spray. It is to be fitted out with an sc 60 i.c. engine. I have 2 spare cans of clear laquer automotive spray, can I use this stuff to fuel proof the inside of the hull? Alternatively I could use the old fashioned way and paint it with polyurethane varnish. Shame to have brush marks on a nicely sprayed hull interior though. Before any one says anything, I like the interior to be just as good as the outside, gives me job satisfaction. comments appreciated thanks keith
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17 July 2012 at 05:46 #3874
captainslog
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@captainslog
17 July 2012 at 19:12 #35304
Paul T
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@pault84577
Keith

Instead of fuel proofing the inside of the hull it might be better to fool proof the refuelling and maintance procedures and prevent spillage.

You could fit a permanent drip tray below the motor.

Paul
17 July 2012 at 20:34 #35305
Dave Milbourn
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@davemilbourn48782
I doubt if their clear lacquer is fuel-proof, Keith. Like they say in all the articles, try it on a piece of scrap first. Me? I'd reach for my Badger airbrush and some 2-pack fuel proofer (did it used to be called "Tufkote"?). Try De-Luxe Materials' website – they must do something like that.
Suit yourself.
Dave M
19 July 2012 at 13:31 #35333
captainslog
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@captainslog
thanks both, bit difficult dave to try it on scrap, unless i strap an engine to it. As an avid aero modeller as well as marine, I have seen the damage caused to airframes from the exhaust fumes on non fuel proofed nylon/balsa. I realise that exhaust is directed to the outside of the hull but believe me where there is a slightest hint of a small gap in the ducting inside the hull the fumes will find it and as the hull is balsa/ply construction it wont take long to take effect. I thought tuffcote was to do with stuff you put on your shoes in the old days lol. I was just looking at the expense thats all, my policy is "if you got use it" but at the moment it looks like a coat of polyurethane, better to be safe than sorry in a couple of years down the road
20 July 2012 at 07:52 #35340
Paul T
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@pault84577
Keith

For fuel proofing a model boat why do you need to strap an engine to a test piece, after all you are testing the application not the engine nor the exhaust products.

When accurately testing samples for fuel proofing the usual practise is to submerge the sample in a container of fuel mix and check its condition every hour.

In testing I have found that Ronseal spirit based products are functional at fuel proofing but as Dave suggests It is always advisable to use the best, for me the best is International Yacht Varnish for others it might be tuffcote.

Paul
20 July 2012 at 08:30 #35342
Dave Milbourn
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@davemilbourn48782
In my experience yacht varnish goes yellow very quickly, whereas Tufkote (which you can still obtain, BTW) stays crystal clear. This doesn't matter so much on natural wood finishes but looks horrible over pure white. Tufkote also sets/dries much quicker and can be sprayed with just slight thinning. While I can sympathise to an extent with the "use what you got" axiom, there's another one about spoiling the ship for a hap'worth of tar……………….
(I never thought I'd ever be singing the praises of anything 'Ripmax', so please note that Tufkote can also be bought as Rustin's Plastic Coating!)
DM
20 July 2012 at 08:58 #35343
captainslog
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@captainslog
thats just it paul, you are testing the exhaust!!!!! You arnt exactly going to tip fuel above and below the leading edge of a wing now are you? The reason aeromodellers fuelproof exterior parts of the airframe in direct line with the exhaust is for the simple reason that exhaust fumes are somewhat corrosive to dope soaked nylon and balsa. believe me i flew a few control line planes with no fuel proofing applied and they were lucky to survive 2 seasons. However you can get away with no proofer on diesel engines as the constituents dont do any damage, only glow fuels. Anyway I digress, it looks like its a coat or 2 of the ubiquitous polyurethane varnish, will have to find another use for the laquer. thankyou all for your comments they were interesting to say the least. Or we can carry this on and see what develops
20 July 2012 at 10:14 #35345
Paul T
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@pault84577
Keith

Your initial enquiry was about fuel proofing a model boat and all the advice so far has been based upon this premise so there should be no reason to test the exhaust unless the outlet is forward of the transom.

I have no doubt that you have considerable knowledge about model aircraft but you question did refer to a boat.

Paul
21 July 2012 at 22:08 #35382
captainslog
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@captainslog
some interesting thoughts there. Tried the laquer on some scrap but it reaxted with the white so iy seems like the good old polyurethane. I know it fades in time and turns a yellow colour but better safe than sorry. Cheers all I`ll consider this thread closed.However whether we discuss boats or airplanes when it comes to techniques applied to the job in hand surely it doesn`t matter which faction the advice comes from? you can only improve by learning from other peoples experience.I promise not to mention a@@@@@@@s again unless its got floats on or is a flying boat
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