Continued...

If you want a TERRIFIC finish, you'll probably want to damp sand. I start by getting a roughly 2x4 inch piece of 400 grit wet/dry sandpaper, a small (disposable or non-eating-out-of-it-from-now-on) bowl of water, an old towel, and a couple paper towels. To damp sand, dip the paper into the water, then shake off the excess water or daub it on the towel so the sandpaper is very damp but not dripping wet. Then sand the surface in SMALL OVERLAPPING CIRCLES, while simultaneously ROTATING THE PART IN YOUR HAND. DO NOT sand in straight lines back and forth, or sand in the same spot continuously... ALWAYS keep the sandpaper moving, and rotate the part so that you're not sanding in one spot, which creates flat spots. DO NOT put too much pressure on the paper-- let the grit of the paper do the work, slowly grinding off the surface of the primer or material. (By the way, these are the sanding motions and principles you should use on ANY sanding, wet, damp, or dry, shaping balsa or doing fine finishing work). As you damp sand, you will notice the particles coming off the surface will combine with the moisture in the paper and start to form a thickening "sanding mud" on the surface of the part and the paper... as you continue to sand off more particles, this will get thicker and thicker. After a couple minutes, dunk the paper in the bowl of water, and rub your thumb or fingers over the surface of the grit-- this will dislodge the trapped particles and wash them away. If you want to inspect the surface, gently wipe away the sanding mud with a damp paper towel, and then dry the surface with the dry clean paper towel... or you can continue damp sanding until the entire surface has been damp sanded and then clean and inspect. Just keep repeating the process working your way up the cone, rocket, whatever until you get to the end. Clean it off with a damp paper towel to remove all the "sanding mud" and then dry the slightly damp surface off with a dry, clean paper towel. Inspect the surface by holding it up between your eye and a distant light source-- a brightly lit window, lamp, chandelier, etc... Look at the "glint" of reflected light on the surface of the tube or cone, and inspect how that glint looks... if you can see waviness, pits or imperfections or low spots, nibs or hard particles or high spots, and SANDING SCRATCHES, they will ALL be visible in this glint of reflected light. You probably won't be able to feel them or see them looking at them directly, but the reflected light acts just like a laser reading the tiny hills and valleys in a CD or DVD, showing things you cannot see directly. If the reflected glint is perfectly smooth, the surface is done. If you can live with any imperfections you see, you're done. Allow the parts to dry for an hour and you're ready to paint.

You CAN still ruin the surface at this point by misapplying the paint... paint in thin, quickly and evenly applied coats to prevent the dreaded drips, runs, and sags. Avoid "dry spray" and "orange peel" through proper distance of the spray from the surface (not too far away) and runs and sags by not getting too close to the surface or spraying too heavy a coat. If you apply the paint properly, there is NO need for any 'color sanding' of the final paint coat-- it should flow out evenly and smoothly on the surface without any flaws or blemishes at all... and you'll have a GORGEOUS finish...

I paper my fins with printer paper and white glue, and most rocket tubes are glassine, so even fins and tubes can be "damp sanded" for great results... the key is to remember your DAMP sanding, not WET sanding... the only moisture should be on the paper and the very surface of the primer being sanded... there SHOULD NOT ever be water "dripping" off the rocket. Wipe off the surface with a damp paper towel periodically if you're worried about moisture buildup (and to get rid of the 'sanding mud' before it dries out and is hard to remove). The sanding mud actually helps the sanding, BTW, because it "polishes" the surface as you sand-- you can actually get a mirror finish in primer using damp sanding if you try! Of course you don't really WANT it THAT finely polished, as you want SOME "tooth" for the paint to grip the surface of the primer, meaning it should be slightly dull... Don't sand with too much pressure to avoid sanding scratches, which are hard to remove and will show through paint. Sanding in a small overlapping circular motion and keeping the parts your sanding moving (or move around on the surface constantly) and avoiding "straight back and forth" sanding motions (to the extent possible-- sometimes you "have to" up against fin roots/fillets and launch lugs and stuff) will give the best results, regardless of damp or dry sanding. How far you take it and how good you want the appearance is up to you... you can quit at "looks good from 15 feet away" or you can put a museum-quality finish on a rocket if you desire, I've done it, so can you if you want...

I've got some build threads and incorporate papering fin tutorials and hardening balsa tutorials, and primering, sanding, and damp sanding tutorials in them... look for the "Dr. Zooch beta-build" threads I've done... If you want links lemme know and I'll look them up...

Later and good luck! OL J R

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