shop talk

Steve Condon

Painting fiberglass fuselages

In the first installment of my column, I will repeat a posting that I put on the RCSE exchange a while back in response to questions about how to do a light, durable paint job on a fiberglass fuselage. This method will, of course, work on a wood fuse that has been properly sealed as well.

I've painted a few fuselages (hundreds, maybe) and the quality of the paint job is usually directly proportional to how much time and money you want to spend. I will tell you how to do a "stellar" paint job (that's light) or the quick and cheap ( also light) paint job that will serve its purpose.

The first thing to remember about any paint job is that the preparation is 90% of the work. The better you prep, the better your finished product will look and last.

The easiest prep I've found is to sand the fuse with 320 aluminum oxide paper until you have a uniform flatness to the gloss of the fiber glass. Make sure there's no shiny spots. If you go through the resin and expose the glass cloth anywhere, smooth it with a wipe-off application of thin CA & a "light hit" with the 320 paper to fair it in.

I use White #7 Brand (green & white tin about $2.00 at Ace Hardware) polishing compound to fill pinholes. A great idea (I believe it was Mark Levoe's originally) for a quick, easy and light method of filling the pinholes. For bigger voids use PPG spot putty.

Since I'm usually too impatient to wait for the stuff to dry on its own, I put a space-heater in my guest bathroom for a mini autoclave (complete with vent fan!) and hang the parts in there to dry. I leave the sanding dust from the last pass of sanding on the fuse, liberally but uniformly wipe-on the #7, hang it up in the clave for 20 minutes, wipe it off and repeat the process two or three times. You're now ready to paint.

Stellar Paint Job

I recommend you go to a professional auto paint store for the really good stuff. PPG makes great paints. Their Acrylic Urethane is the best I've found for easy application (using a gun) and best results with respect to coverage, weight, and overall "killer gloss." If you choose this type of paint, you MUST use the right kind of primer. I prefer the PPG white Epoxy primer or K & B epoxy primer.

It is important to mask and "rack" all parts for painting so you can safely set them down or hang them up for painting and curing. In addition, I also highly recommend the wearing of surgical gloves, respirator and protective clothing along with adequate ventilation. I usually construct a makeshift spray booth in my garage with plastic dropcloths and box fans to take fumes and over-spray out under the door which I leave open about 18".

If you do a good job priming, the paint will usually cover beautifully in one coat. However, the majority of the weight can be in the primer. I prefer to "dust" on a first coat. I mean really REALLY light, so you can see through it all over. If there are any obvious nasty pinhole spots that you want to eliminate, use the #7 method (don't worry, it's paintable!).

After you're satisfied, shoot another light coat on and put the fuse back in the "clave" for 10 minutes. If it needs another coat to cover dark areas, hit it lightly.

If you've done a good prep job, you can go right to color coating. If the surface has blemishes you want to remove, sand, fill, sand etc., until you are satisfied. spot prime the affected areas or the whole part, if necessary.

I usually final sand the primer with a used piece of 400 paper (wet) and dry it, wipe it with a smear of thinner to remove finger oils, and finally a tack rag for lint.

The trick to good coverage with any paint is to have the air pressure right, the paint thinned properly for the temperature, and to FOLLOW A UNIFORM PATTERN laying each pass partially on the previous one to create a "wet line" as you move. Good lighting and the proper angle is essential to see the line clearly.

Note: the first pass (on the whole part, uniformly) should always be a "duster" from a greater distance than normal. Immediately follow with a second (and hopefully final) pass that covers completely at a level of "wetness" that appears glossy but not so heavy that it will drip or sag.

Let it cure in a dust-free environment with good ventilation. Again, the "clave" thing works great for me. Having an understanding wife is a must to pull this off!

If you follow this method, you will get an incredibly good looking light weight paint job that will last for as long as your model...hopefully, a long time!

I was able to paint an all-carbon Blackhawk and add only 3.2 oz. to the overall weight by painting the top surfaces and fuselage. The primer weighed 2.4 oz., and the one coat of color was .8 oz.!

Quick and cheap

I use spray can lacquer for the "quick and dirty" paint jobs. Personally, I would NEVER use Krylon. It's too heavy and it doesn't last. If you're going to go spray-can, use lacquer. It is lighter, just as fast, and it is a little more durable.

Here in Southern California, Pep Boys sells Plastikote "Classic Lacquer" for about $4 per can. Buy the color of your choice and clear. As far as spray-can primers go, I have found that "Varsity" white primer is the best. It's light, white, and dries in a blink.

Use the same methods to prep as described above. Again, preparation is 90%!

For Hand-launches I dust-on a coat of primer and that's it. By "dust" I mean to hold the can far away (like 24") from the subject and just fog the paint on until it looks like a coat of dust. Stop there! don't get carried away and put a whole bunch of paint on; use just enough to help the color stick. Then dust two coats of color on right in a row, shooting the second one a little closer so the paint flows. Again, don't get carried away and put too much on. It may look great at first, but odds are it will drip or sag while drying, and you may attract undue attention to yourself with all the loud swearing that follows this discovery.

Remember that lacquer dries with a satin finish. If the coverage of the application described above looks good, let it cure for 20 minutes and shoot a light clear coat on it. I have found that clear lacquer is VERY light weight (.5 gr. per coat on a HLG fuse) so, I usually do two coats for nice gloss and a little more protection.

After the clear coats, let it cure for at least a day and you're ready to fly. A week later you may want to rub a light coat of wax on for added protection. Lacquer won't withstand the abuse of solvents well at all; even rubbing alcohol can mess it up, so be careful what you let come in contact with your new paint job. Happy painting!

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