Hi there.  I am just about at the finishing stage of a 1/2a control line airplane here and had a little question regarding the finishing of it.  I would also lik eto save weight so thought about a tissue paper covering for it to add just a bit of color.  So my question is about dope substitutes.  Mainly, MinWax Polyurethane clear varnish.  Has anyone tried it to seal a 1/2a plane and found it to be fuel proof?  It is a lot cheaper than dope, if I can even find any locally, as well as I would be able to use it on other things as well.  If not, I may do a test myself, but just thought I would see if there was anyone that has tried it.

Ps.  Plane is a 1/2a White Lightening, profile fuse, solid 1/8" flat wing.

You could look at Rustoleum or equivalent. Cheap, comes in spray cans at the hardware store.

Chauncey, even Butyrate dope isn't completely fuel proof if you are using a high-nitro content 1/2A fuel. I believe you have experience with 2 part automotive clear coats. Other than that an epoxy clear or polyurethane will do the trick.

Chauncey,
If you are using tissue to cover open bay areas then you need something that will shrink the covering tight, this is dope. If you are covering solid wood you can use the Poly or Rustolum but it will add more weight then the dope. For a fuel proof top coat you could look into KBS diamond clear (https://www.kbs-coatings.com/DiamondFinish-Clear.html). They have a small more cost effective (at least for our purpose) "Clear Coat Kit" look down the page.

Best,     DennisT