For the finish of the balsa parts model dope would be an excellent choice as it dries to a hard and easy to sand finish. Next up would be clear coat. Last and worst is varnish as it remains soft and tends to clog the sandpaper. Clear or white shellac would be a nice finish that’s easy to sand smooth.
For me, the most reliable way to seal balsa for painting is using fiberglass cloth and epoxy finish resin or a water-based polyacrylic. I’ve had no luck painting raw balsa. It doesn’t have to be glass cloth, and epoxy, cloth, and diluted PVA rubber will also work. Although tissue and dope are still popular.
Usually 1-2 coats of primer is fine, but you need the extra coat because balsa wood is very soft.
Because balsa wood is so soft, it doesn’t pick up wood stains as easily and evenly as hard woods, but applying a coat of wood conditioner solves this problem.
Use a seal, e.g. B. a sanding finish to prepare the wood for painting. This prevents the paint from being absorbed by the balsa wood. Allow time for sealant to dry.
Every time you oil or varnish or varnish balsa, it will pill and dry to a rough, hairy finish that needs sanding to smooth and prepare for the second or more coats . While making all of these pieces is tedious, making them flat or as sticks will be infinitely easier than doing it later when it’s all together.
RE: Impregnate balsa? Sealing balsa wood or extra light plywood (which I believe is made from stale salt) is a good idea. Polyurethane varnish has been mentioned. Diluted epoxy (epoxy + denatured alcohol) is also good, as is fuel resistant dope and balsarite.
To color balsa wood, you need to finish sanding all parts first, after coloring you can’t sand – the layer of color is so thin that it will peel off if you sand after dying. You will need to stain the wood prior to assembly as the color will take differently on bare wood and wood with glue applied.
You will need to soak the wood (or the area that needs bending) and bend it into the desired shape and let it dry. I personally like acetone, but try alcohol first. Remember, the harder the wood, the harder it is to shape. sometimes heat also helps.
Pre-treatments for wood
Apply two thin coats of sanding sealer. Follow with two light applications of a mixture of 1/2 linseed oil and 1/2 turpentine. Using a brush, apply two thin coats of spray sealer or polyurethane. Polish the surface by hand with a soft cloth.