Just looking for some thoughts on finishing a semi-scale Supermarine Spiteful I'm working on at the moment.  As you can see, the whole thing is sheeted/planked.  Normally I'd seal the balsa with a few coats of dope, apply silkspan, then more coats of dope, sanding sealer, primer, paint, etc - but is there a better way?  Would it be significantly heavier to use thinned Z-Poxy to seal the wood instead of the initial coats of dope?  If I do, could I get away with not using silkspan at all?

The model is not intended as a competition stunter, more as an aerobatic sport model.  Span is 53", area about 560 sq.in., and power is a sidewinder PAW 35TBR which I've had sitting in a drawer and would like to see flying.   I've already made a few weight compromises for appearances' sake (eg heavyish diamond-tread wheels, strut covers etc), so would like to avoid the finish being any heavier than it needs to.

Cheers
Steve

Steve,

You can also go with two coats of Defthane sanded between coats to seal the wood and then finish with dope.

Bob

Thanks guys, looks like I'll stick with the dope then.  I've had concerns about shrinkage causing dips between the ribs, but I'll try to get around that by adding a bit of castor as a placsticiser.


Cheers
Steve

waterbased polyurathane  seals the wood and sands smooth - wood filler in any low spots -sand - then apply finish coats - REAL easy.  Light and gives a good finish

Watch out if you are using something like Polycrylic (water based urethane). It can warp the wood if put on raw wood (ask me how I know).

The point of using resin like Bob Hunt did was to harden the wood so that you can fill the grain providing a barrier so that the wood doesn't soak up too much material and so get heavy. Silkspan does much the same thing but you get some strength out of it too. It's certainly possible to use a material to harden the wood. Thinned epoxy, resin or other material can work and I've done both. As Bob noted, you have to get as much off as possible. You just want to harden the surface. Were I doing this, I think I'd try urethane. Shoot on two part polyurethane clear, wipe off as much as possible. Once it hardens, sand then shoot a catalyzed primer like K-36 to fill the grain then shoot urethane auto colors and a catalyzed polyurethane top coat. Few coats so pretty light. Easy and should look good.

But as others have said, probably better to go with what you know for this one and build some easy profile to experiment on.

My next weapon will be fully sheeted, no open bays,, ( well excepting the engine compartment with the hatch removed,, ) 
I plan on using light tissue, and catalyzed Urethane clear as a base to harden the surface. My PLAN is to do like the old glass method of sticking it down, then blotting off the excess. This will be lightly sanded after curing, followed by one coat of K38 catalyzed priimer. That should see the project ready for paint assuming my woodwork is well done before the base clear.

I have always rolled the toilet paper over the resin on the surface, after screping most of it back into the cup with a credit card ( wife's work best!) - but always roll it so the paper stays on the roll. After a pass down the surface,  unroll the resin soaked layer to expose fresh TP for the next pass.  Soaks up the excess and spreads it evenly at the same time.