Priming cowling

Ok builders, I'm looking for advice on priming my cowling. I plan on having it painted soon but I want to fly now. Is there a particular primer recommended? I have a pink cowl and want it covered for the time being. Advice?

Mike,
I filled the pinholes in mine with "neat" epoxy and sanded it smooth. Then flew with it till I got it painted. Search for "DanH" posts on epoxy. It's really very easy and will protect it for quite some time before painting.

If you go with a primer, don't go for the cheap 1 part rattle can type cellulose stuff. It is soft, crappy and not compatible with some paints. Get a high quality 2 part primer. Pricey with reducer and catalyst but you get what you pay for and you will save yourself the possibility of future nightmares. If you know what paint you will use for the top coat the stick with that mfg's primer recommendation.

I used Epoxy to fill the holes and weave (multiple coats) and lots of sanding. Then I sprayed Stuart Systems waterborne primer/sealer. It's a 1 part grey filling primer. It's holding up well thus far at 70 hours and can easily be sanded back down for top coat of primer / paint when the time comes. It all kind of depends on how long you will fly in primer. If it's a short time, then fill with epoxy and leave it. If it's longer then getting an even color with primer is an easy way to go.

Cowling Pin Holes

I'm currently working on filling pin holes and getting ready to paint. Tried the 50/50 epoxy/acetone mix. For me this did't work. The epoxy (West) did not cure right although my mix etc was right. I've been using West for some time with good results. I called West Systems and they said you should not put more than 5% acetone in it. They recommended to squeegee in neat epoxy to fill pin holes (like other VAF posts) - should have known better. Vans said it worked for them when they wrote the manual but things may have changed. After 5 days "cure" it was set up just enough to coarse sand it off with difficulty - still balled up and plugged the sand paper.

From now on it's neat for me like my coffee & other beverages.

Plan on using Pro Form epoxy primer and a urethane top coat inside & out. Haven't decided on the brand of urethane.

Be aware that UV from the sun will destroy epoxy over time. It will turn all cloudy and the turn to powder, it needs a top coat of some kind to protect it from the sun.

Mike Coady said:

Ok builders, I'm looking for advice on priming my cowling. I plan on having it painted soon but I want to fly now. Is there a particular primer recommended? I have a pink cowl and want it covered for the time being. Advice?

Click to expand...

I used PPG K-36 primer/filler for the cowl, wheel pants & fairings. It sprays on nicely at low pressure, and is very durable... easy to scrub and holds up well while getting the bugs off. I hadn't planned to fly my RV-7 for two years before paint... but its been way too much fun to surrender it to the painter.

By the way, my painter also uses PPG K-36 primer/filler and was glad to see it is what I had used.

Don't bother with filling the pin holes.... leave that to your painter. They love doing that sort of thing.

Cheers,

I cut back my West Systems Epoxy with about 25% acetone. Brushed it on and then scraped it off with a credit card about 1 hr later. (slow hardener). I did this 3 times about 3-4 hrs apart. Then sanded 1 time after 24 hrs. Wet sanding with 220 grit worked best. I think I found 1 pinhole when I put on a coat of primer later so I'm sold on the cut back epoxy. I did have one batch I put on my gear leg fairings that took forever to cure. Maybe I didn't measure my squirt just right on the hardener on that batch. I have my west system pumps measured and marked at 1/4 stroke intervals and have had great luck mixing small batches except that 1 time with the gear fairings. It takes a surprisingly small amount of thinned epoxy to cover lots of area. I'm gonna paint before flying but if I wasnt, I would put the 3 coats like before and skip the sanding unless you want a coat of primer for even color. I bet the un sanded glossy epoxy finish would be very easy to keep clean.

sblack said:

Be aware that UV from the sun will destroy epoxy over time. It will turn all cloudy and the turn to powder, it needs a top coat of some kind to protect it from the sun.

Click to expand...

Might depend on the primer but, in general, do primers provide UV protection or does that require the solids in a top coat?

For PPG primers, they do not provide UV protection. The PPG top coat provides the UV protection.

Cowl primer

If you prime the cowl with anything other than 2-part epoxy primer, most painters will tell you ALL the "cheapo" primer must be sanded off or removed with solvent prior to painting.