By Reinhard Metz on Thursday, October 24, 2002 - 09:02 am: Edit

My wing fairings were sealed to the plane with white silicon rubber, and I have no leaks or loss of adhesion. It was installed by prying the fairing away with tongue depressors, and injecting the silicon rubber. There are two considerations, however: 1) You need to tape off the adjacent area carefully, as the excess silicon rubber will not come off easily, especially a thin smeared film. While not immediately visible, it will become dirty later. 2) There is enough flexing in the wing fairing (in any case, whether glassed in place or just sealed) that the paint on the fairing needs to have a flexing agent (like impact coat) added, or it will crack in that area, especially if it is a hard catalyzed urethane.

Here's the overview of what I did for paint and finish, as was in the Dec '99 - #21 CBROS newsletter. Again, I owe most of what I learned here to Jerry Sjostrand, who taught me how to paint and finish.

1) Filling of low areas and contours (after glass) was done with Evercoat 100838 Chrome-a-Lite for rough areas, Evercoat 10040 Polyester Glazing Putty for the finish fill. Both of these harden quickly and without surface tackiness.

2) All sanding 320 random orbital or by hand, dry, not wet, wet is too smooth for good paint adhesion.

2.5) I also used a sprayable polyester filler in some areas where there was no Jellcoat and the pinholes were too much for primer. This stuff is a lot of work, though, because you basically end up sanding most of it off again, just to fill the pinholes.

3) I used Spies-Hecker catalyzed Urethane paint. It is a fabulous material - results are astonishing, but so are the prices! Vario 8590 primer, sanded at 320, fix any revealed defects now. (This material must all be applied with a fresh air respirator, preferably a full suit, if you expect to survive!!) Clean all surfaces with Prep-Sol and wipe with tack rags for every paint application.

4) Finish coat was Spies-Hecker Permacron series 257 in white, colors with clear-coat for stripes. Spray one extremely thin tack layer, let almost dry - about 20 minutes, followed by two full wet coats separated by about 20 minutes. The idea is to get chemical adhesion, but as late as possible to avoid running.

5) When the finish coat is hard, but not ancient (between 36 hours and 1/2 year), wet sand (air random orbital sander) with 1200 using 3M 01318 adhesive backed resin coated sanding disks. Precede this with a thin layer of "guide coat", which is a lacquer, like red or black primer, that is sprayed thinly on top of your finish coat, that will be sanded away and will quickly show any surface irregularities or places you missed with the following sanding step. It also shows you exactly when any orange peel is gone - it is the way you get the paint perfectly flat. Use this 1200 grade step to get rid of all small imperfections, and be prepared to re-paint any large ones, or live with them. During the 1200 step, keep a trickle of water flowing, use good lighting, and squeegee dry periodically to monitor progress along with disappearance of the guide-coat. I can't emphasize enough the importance of the guide-coat, and it's entertaining to watch others when you do it too, because at first it looks like you are totally vandalizing your beautiful finish coat! Do be careful not to sand through the paint and stay 1/4 inch away from edges. This also means you need to tape mask the edges and details, like countersunk screw holes, before the guide-coat step.

6) Follow with 1500 3M hook-backed resin discs on the random orbital wet sander, with a foam inter-pad. With care, this combination can be used out to the edges.

7) Hand wet sand with 2000 grade paper. This is essential for the final stage to be able to reach a full polish.

8) Now for the magic - The last step is polishing with 3M Finesse 05928. Use a power polisher with a yellow lamb's wool pad (not white). Follow the 3M directions - This stuff is high science - it does not remove material - it polishes by re-flowing the paint at a molecular level, but it can only do so up to about 2000 grade roughness. Be careful, though, not to burn the paint - use light pressure at the end of the process. You can let steps 5-8 go onto the Plexiglas windows, as the Finess will return them to optical grade as well.

So, that's it. Experiment, talk to folks at paint stores, be prepared to do stuff over. Good Luck!

Reinhard Metz