Balsa surface preparation for iron on covering

[mgdon]

After flying foamies for a while I'm building a Stevens RV4.
What surface preparation is best before applying iron on covering?
I'll be using doculam and painting the reverse side of it first.
I realize the surface should be at least sanded-but how smooth and with what grit paper?
Should some type of sanding sealer or primer be put on the wood before covering?
If there's a book or thread on this subject please let me know.
My apologies if this has been covered before.

[Bob E.]

I just sand it, wipe off all of the dust, and cover with Monokote. I've never used any kind of sealer, nor have I had any problems to date.

[fhhuber506771]

usually.. just sanding to the desired smoothness and then iron it on. I always sand to at least 220 grit. A scale model you might want to sand to 400. Anything beyond 400.. you won't see the difference after the Monokote (or similar cover) is on.

You can increase the fuel resistance and covering adhesion a lot by applying a coat of Balsarite in the areas of expected overing seams. (thinned yellow glue helps some if you don't want to pay for the balsarite) I thin my balsarite with acetone to make it penetrate the wood better. (its kind of syrupy thick)

if you want you can paint the Balsarite over all of the aircraft before covering. It does aid in preventing fuel soaking the balsa and the cover sticks better. But it adds weight, and it needs to dry at least a day before you cover. (3 or 4 days is better)

I "paint" the inside of the aircraft in the fuel tank area and anywhere I think fuel would go if the tank burst with 2 hr epoxy. This has saved a couple of aircraft from fuel soak damage when tanks have leaked. (also provide a hole under the tank for fuel to run out if the tank leaks) The fom packing arond the fuel tank can soak up a lot of fuel.. and hold it next to the wood. I have started putting the foam packing in plastic wrap so the fuel can't soak the foam.

[mgdon]

Thanks Guys!
You've told me what I needed to find out.
Sorry I guess I should have said it's going to be electric powered.
I may try the thinned balsarite on the seam areas though.
Don

[Viper Pilot]

. . . . Sorry I guess I should have said it's going to be electric powered. . . . .

Then maybe this should have been posted under Electrics, huh???

[mode1]

I final sand with 400 if covering with plastic. After sanding I use low air pressure to blow surface while brushing with old paint bursh. Knocks off the sanded wood dust. Final wipe with lint free cloth or commerical dust rag. After covering is complete I go over all the edges with water base poly-u on small brush or cotton swab. Milky when wet but clear when dry. Edges never lift.

[mgdon]

Viper,
I don't see where the type of powerplant makes much difference as to a question about covering a model-except fuel proofing.
There didn't seem to be that type of question being asked in the electric beginners area so I asked here.
"Mode1",
Thank you-I'll follow your procedure exactly-I even have some water based Polyu I can use.