Hello AAN2705,

I can only tell you what I do and from there on you are on your own.

In effect we are beginning the process of finishing and covering the structure of the model.

Some balsa has fine grain and some has coarse grain.

Fine grain surfaces

Use genuine aircraft dope as used by full size airplane refinishers.
Apply by brush a first HEAVY coat of nitrate diluted about 15% by volume with nitrate dope thinner. Just enough dilution to make it easy to brush on.
Let cure for 12 hours or any length of time more than 12 hours.
Dry sand smooth LIGHTLY with 320 grit paper.

Apply a second heavy coat of nitrate dope (diluted as above) and let cure for 12 hours minimum.
Wet sand with 400 grit wet abrasive paper.
Do not let any water go on and penetrate the wood areas not being finished. (Avoid warping).

You now have a smooth surface ready for the covering.

Coarse grain surfaces

First coat of nitrate as above for fine grain.
Dry sand smooth LIGHTLY with 320 grit.
In a separate small container poor the quantitiy of nitrate dope you expect to need.
Add talc powder to nearly double the volume in the small container and mix thouroughly for one minute (NO MORE THAN ONE MINUTE0 .
Add the solvent (thinner) just enough to make it spreadable with a brush.

MAKE SURE YOU ARE USING HIGH QUALITY BRUSHES THAT DO NOT LOOSE THEIR HAIR.

Apply this second coat always brushing cross grain and pushing a bit hard on the brush to help the mixture to go into any pores, tiny cracks, etc . . . Do not overcoat with this mixture. You can always apply an extra coat where it becomes obviously needed.

If, inadvertently, you have an ovrcoated area that started to cure, use clear thinner to dilute it on the surface and spead it out.

Let that second "filler coat" to cure 18 hours or more.
Wet sand as above for fine grain.

NOTE: I seem to be telling you what to do. I really mean to explain what I do.

Hoping this is valuable informaton for you and any reader.

Zor