I live in Central Florida, where a good portion of the year the temperature stays in the 90s. Although I keep my planes out of direct sunlight as much as possible, the black paint gets "alligatored" even with the short exposure they get. Is there any coating or other process which will make the black paint more resistant to this effect? I realize scale paint jobs require black anti-glare panels etc, but it would sure help hot weather flyers if black were minimized. Is it possible water based polycrylic would help retard this effect?
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Its about the temperature that reaches the foam that causes the gatoring. Not the chemical makeup of the paint.
On full sized aircraft that used traditional dope and fabric, before the color coats we used to apply a coat of aluminized dope over the entire fabric. It was regular dope that had aluminum powder mixed into it. Very deadly to breath and dangerous if caught fire. Anyway, the theory was that this provided a heat/UV protective barrier on top of the fabric to help prevent deterioration.
So, I know mixing an aluminum powder mixture is out of the question for weight as well as cost and the health hazards but I've toyed with the idea of using some sort of silver/metalized/reflective base coat before applying the top color coats. Short of glassing the area I just don't know. I may have to do some experimenting. Either way, if the critical temperature ( don't know what that is) reaches the foam it's going to start that bubble thing. As we all know, the black under the canopy is the first to go.
I wonder if Alpha has already gone down this road and what his findings are? He has said he's done a fair bit of experimenting on color as well as reflectivity of the paint on it's resistance to "gatoring". If I recall, the obvious is the lighter the color the better but What I thought was contradictory he said the flatter the finish the less likely it will gator. Or, maybe the "flat" just doesn't reveal the gatoring as prominently? -
VOODOO I live in North California where 100+ is the typical temp in summer. Unfortunately the mix of high temps and UV rays are very detrimental to our foam birds. The system which works best for me is laminating with 1 or 2mil Orocal vinyl. I have a couple EDF's dressed in black vinyl which keeps gatoring to a minimum. The other material I have used is Spar varnish (oil based). Although the varnish does add more weight than vinyl , a couple coats of gloss will shed the UV rays and will keep the gatoring in check, because spar varnish is an amber color which darkens over time I only use it on black and dark colored birds
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I fly at 7000 ft. The sun can be absolutely brutal, here. Just 5 or 10 minutes of flying can start the gatoring, especially under the canopies and black paint. Keeping your plane in the shade as much as possible seems to be the only answer. DocComment
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I wonder if the alligatoring is caused primarily from surface temperature or also the uv radiation?Comment
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I believe it is simply a matter of the temperature the foam reaches, not UV exposure or the type of paint used. EPO foam will gator if you pour hot water on it. I believe it is the chemical make up of the foam. It is a petroleum based product that still contains some gas after the manufacturing and molding process. When it gets hot the gases still in the foam cells expands causing the individual cells to balloon, what we see as the "gator skin." Areas that are painted a dark color simply absorb more heat, which causes the gas in the foam to expand.Originally posted by VOODOO View PostComment
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That gives me a thought, why not use a perforating needle roller over the entire surface, warm up the foam to whatever the temperature is that causes the gatoring and see if the bubbles will off gas without bulging? Then just apply a primer coat to seal everything up and repaint? Might be worth an experiment...Originally posted by wvrailfan View PostComment
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