I was told that I need to dope the whole plane before I cover it with 21st century fabric in order to fuel proof the plane before covering, Does anyone have any thoughts on this idea or maybe alternatives?

Tree Top Thrasher:

I'd paint it before covering, but not wth dope. Give it a coat of "Balsarite for Fabric," it will act as a sealer for your final sanding, (after painting the Balsarite) and help the adhesion of the fabric.

My way is to paint the firewall and the tank compartment, and sometimes on back into the radio area, with thinned epoxy for fuel proofing, and I do it before covering. That way I don't have to worry about dripping the epoxy on the covering.

And for those areas where the epoxy gets around on the outside, the places the fabric usually won't stick, with the Balsarite the fabric sticks just fine.

HTH

Bill.

Tree-top-thrasher....the reason to give the plane a "first coat", before any covering...is to seal the grain....I usually give my models a coat of diluted dope / talcum powder.....when dry, a rub with 600-800-wet/dry has the surface really smooth, also shows up problem areas very well, before the final stages....

Cliff

I recently tried a new technique that worked very well. I thinned carpenters glue with water till it was very thin, and applied it to the airframe. Let dry, then sand with very fine paper (I think it was 540). The results were excellent. (and cheap!)

Note: this is not for fuel proofing! For that I use epoxy thinned with alcohol.

ordinary rubbing alcohol is much more convenient to purchase than denatured alcohol. It's even on the shelf at your local convenience store. And it works every bit as well, or better, since the water in it extends the drying time.

If you like to use epoxy as your normal glue for construction, the pot life is also extended when thinned this way. You can use a small brush to apply it to both pieces before assembly, getting just the right amount in the joint.

Just a hint, hopefully helpful.

Bill.

I've done 4 planes with 21st Century Fabric and done nothing to seal or treat the surfaces before hand other than 400 to 600 grit paper and a wood pecker. I've had no problems with fuel intrussion.

Do it cliffords way when you want that perfect finish with paint or film. 21st Century fabric is a bit heavy to take advantage of a super fine finish.

Opps, everything I said applies to 21st Century PAINTED fabric. If your using the unpainted fabric it's cliffords way all the way.

I never tried minnflyers way.

Thanks for the info guys, Looks like I have a decision to make. By the way, I`ll be using pre painted 21st century coverite

Dope and silk or cloth is the only way to go.

Kraus