Sealing Decals From Fuel

I used to seal all of my decals with Minwax polyurethane. The only problems I encountered was yellowing. Ken

K --

Fingernail polish generally contains acetone which will melt foam. If you decide to try fingernail polish, test it on a safe location before use.

I usually seal trim and decals with clear butyrate dope -- again, you may want to test it on a scrap piece of decal material. Some decals will bubble or wrinkle with dope.

andrew

Thank you for all the responses. Rusty, may I ask how long the polish took to turn white? I usually use a light spray of Windex on a paper towel. I read elsewhere that Windex contains isopropyl alcohol, but I don't know if it contains enough to harm the polish.

Either way, I have three types of polish on a test piece now and will give all three a go with Windex. I'll post the results...

KP

I am sure that clear finger nail polish will not be fuel proof. The main constituent is nitro cellulose and this is not fuel proof.

A coat of butyrate dope will be fuel proof but only with low nitro fuels. From the Windy videos I watched, it was his conclusion that it was only fuel proof to 5% nitro and definitely not to 10%.

From my own experience, butyrate dope (or the version I used) was definitely not fuel proof at 20%.

Ron has been bravely flying the Rocking Donkey - This has decals and was coated with this stuff

http://www.pegasusmodels.co.uk/product.asp?prodid=995857#.VKZsUp1FCUk (probably not available in the US)

I believe he used 30%+ nitro so it would be interesting to see if the decals have survived ( Apart from his attraction to landing upside on concrete and flying into trees! )

It turned hazy white before I ever flew the plane. I would rub some oil on it and it would look a lot better.
Rusty

If you are using polyurethane varnish already, use some more polyurethane varnish to seal the decals. This is easiest and know to work, as long as it doesn't wrinkle or damage the decals. Look up the product you are using, there usually is an amber varnish and a clear varnish in most product lines. Use the clear.

Phil

Ian, as you said, the nail polish wasn't fuel proof on any of the three polishes.  After reading Rusty's post about the nail polish turning white before alcohol was applied, I thought I'd skip the alcohol and go straight for the fuel.  It definitely didn't work with 25% nitro.  Also, I can't seem to find the videos you refer to.  Do you happen to have the link (if not, no worries)?

By now, I'm thinking I will settle on Sig Butyrate Dope (I'll have to go pick some up tomorrow) or Helmsman Spar Urethane.  Phil, my only issue with using the urethane is that I have gotten very grainy results from spraying multiple coats of this stuff (a wet over a dry).  One rather wet coat is usually the best.  By the way, if anyone is interested, I highly suggest checking out post #15-#25 HERE.  This stuff is very fuel-proof, yellows little to none, can be sprayed on lightly, and dries quickly (although my tests have shown that two days of drying is best for "fuel-proofness").

For those more experienced, are there any big hints or things-to-avoid with butyrate? Or is it pretty straight forward?

Thanks again,
KP

Do I understand this correctly that you already put the spar varnish on? If so, it's a oil base product. You can't place dope over top of it. It will alligator the finish. I'm not saying it can't be done, but it would need to be done in light misting coats. In addition, is this a foam wing. If indeed the dope eats through the finish it will melt the foam. In order to get a decent glossy finish you have to thin it which will more than likely attack the underlying surface. Staying back and misting the coats on will help. But if this is indeed a foam wing I would use a lot of caution. While your choice of dope (Sig) is the best in regards of fuel resistance, most dopes have little fuel proofing qualities and they all eventually fail or begin to wipe off.

Ken,

Yes, I have already sprayed everything with Rustoleum Navy blue and then Spar Urethane.  

The wing has been covered with Doculam just like the other parts, so any reaction with the foam can be factored out.

KP