Sanding down the balsa plane body before putting on tissue paper.

Sanding and I have a love/hate relationship. I hate sanding, but I love the results. There's nothing better than finishing a well-sanded piece of furniture. But we digress, this is about covering well-sanded balsa plane model bodies. You have to sand the body because it is unlikely that the stringers and the formers will be perfectly flush after assembly. If you do get the formers and stringers perfectly flush throughout the entire body, then I want to know how you do it!

My favorite way to sand a balsa plane model is to wrap a piece of 100 grit sand paper around my pointer finger. I use the roll sand paper that has adhesive on the back. It is actualy made for a Porter-Cable random orbit sander, but is perfect for this appplication.

A piece of sandpaper stuck to my finger is perfect because I get tactile (ie, touch) feedback on whether or not the pieces are flush. Basically, I put the sandpaper on my finger and then move my finger back and forth until the pieces are flush. The back and forth motion is alot like waving a finger in a "no no no" fashion at a toddler. You'll feel that the pieces are flush when the "no no no" motion is smooth from start to finish.

It is important not to oversand because you'll create a depression in the profile of the body. Airplane bodies have beautiful curves with C2 continuity that you don't want to ruin by putting a concavity in the shape.

It is important not to undersand because you'll ruin the curves the other way (convex). Hence the use of paper stuck to the finger to get the feel just right.