Wood propeller clear touch-up with what?

I have a Bernie Warnke propeller from 1993 to 1996 era, not exactly sure when it was purchased. It is a thing of beauty, and in overall excellent condition , and flies great. The clear finish along the length of the trailing edge is simply gone, not peeling, but like it wore away. This is hardly noticeable, and you would laugh at how minute the actual bare area is.

I would like to seal up this area from moisture intrusion. I wonder what product to use. I fear using something incompatible with the current finish, such that it will just peel off. Also I fear using something that might be bad for the glue between the wood laminations.

Just looking for some sound advice. I think it may have a clear polyurethane on it, but can't be sure. Part of me just wants to grab some off-the-shelf clear poly stuff from the depot or ace.

Thanks

We have a Bernie Warnke prop on our O-320 RV-6. I agree it is a thing of beauty.

Unfortunately I think it had been flown through rain before we got the aircraft and some LE sections inboard of the polyurethane strip had lost the protection as well as some areas on the trailing edge. In these areas the wood has gone grey.

My A&P/IA said to protect it with ordinary Nail polish/lacquer. I just used some clear and it’s holding up very nicely including have flow through some rain.

DonH
Sydney, Aus

^^^^

I had a Performance Propeller with a polyurethane finish and Clark Lydick told me the same thing, use clear nail polish. Worked like a champ

I had a Warnke. I used spar varnish from Lowes… Helmsman I believe the brand. Give it a light sanding, tack cloth clean, then brush on light coat.

Bernie Warnke props and touch-up.....

CATPart said:

I have a Bernie Warnke propeller from 1993 to 1996 era. It is a thing of beauty, and in overall excellent condition, and flies great. The clear finish along the length of the trailing edge is simply gone, not peeling, but like it wore away. This is hardly noticeable, and you would laugh at how minute the actual bare area is. I would like to seal up this area from moisture intrusion. I wonder what product to use.

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I think the Bernie Warnke props were the apex of the prop-making art at the time. He had developed the design over decades and had perfected the performance (his Almost Constant Speed Prop) and the looks: laminated mahogany, I believe, of the wood golf clubs are made from. The thin multiple laminations made them one of the most gorgeous-looking props on the planet! When I got mine, I wanted to put it on the wall as ART but needed it on the airplane! And it is a performer! It seems to flex to grab the air better as the prop speeds up. Doesn't seem possible but I swear I can feel it ease into that comfortable cruise. In the later years his wife convinced him to sign them. I have one of the last props he made before he left for the Prop Shop in the Sky. RIP, Bernie! You knew your craft well!

My airplane is always hangared except for being outside on trips. Like, oh, OSH. Where every once in a while it rains. Seems like the trailing edge is what takes the most grief, starting to lose its protective finish as that is where water invariably collects, even with morning dew. Mine was getting a little rough, that you could see if you looked closely but mostly feel. I got some Helmsman Spar Varnish at the Home Depot Aviation Supply Store. Getting the prop horizontal, I ran several thin layers along the trailing edge as it was facing down. I did multiple layers, applied with a Q-tip and avoided it building up on the black protective layer of the back side. That has now been in place for years and has worked very well. I think if I was to refinish it, I would consider spraying rather than brushing varnish on. Smoother finish. I would also do several coats with sanding lightly with 4000 or something really easy between coats. My Landoll Balancer does not make me concerned about it being out-of-balance......

I refinished my Warnke prop about 2 years ago. I did a lot of research into what the boat guys were using to UV protect and seal wooden boats. This was the stuff I ended up going with and what most boat builders seem to favor these days.

https://www.amazon.com/Z-Spar-Capta...86415&sprefix=captain+z+spar+v,aps,118&sr=8-1

Mine was just as yours was/is. The finish was peeling and the bare wood was turning dark and gray in some of the trailing edge areas. I always assumed it was possible air cavitation due to the blade being stalled at that location at certain airspeeds... Either way, I sanded the prop almost completely down, just shy of the carbon at the tips. And not rough enough sanding to damage Bernie's signature!!

I used a foam brush with fantastic results with the Z Spar varnish. I then repainted the white tips, and actually balanced the prop with layers of the flat black paint on the backside of the blades. If the blade was light, it got another fine coat of black paint. It worked out really well. Still looking perfect after 2 years.

As for fixes on the leading edge, I just followed the EAA video "Hints for Homebuilders" on small LE repairs with baking soda and CA glue. Works great, lasts long time. I've raced this prop and spun it to 2700+ RPM on many occasions and the finish and leading edge repairs have never given me any trouble in about 750 hours.

https://www.eaa.org/videos/6008030121001

The entire project was done in a weekend.

Refinishing wood props............

Jvon811 said:

I did a lot of research into what the boat guys were using to UV protect and seal wooden boats. This was the stuff I ended up going with and what most boat builders seem to favor these days.

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GREAT source of information! Who would know wood and water better?

Mine was just as yours was/is. I used a foam brush with fantastic results with the Z Spar varnish. I then repainted the white tips, and actually balanced the prop with layers of the flat black paint on the backside of the blades. If the blade was light, it got another fine coat of black paint. It worked out really well. Still looking perfect after 2 years.

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What was your method of balancing the prop? Likely a good idea after changing the finish, even with a Lendoll..... And what white and black paints did you use? I also see an orbital sander on the table. Did you use that or just hand block sanding?

I used the orbital sander with 400 grit (Over-gritted?) and light pressure to avoid taking too much material off at once. Mostly because I'm lazy... It's definitely not the most efficient way to remove material. Using 120 grit by hand would have removed the old finish faster. I finish sanded by hand before the varnish. 400 grit making sure to sand at a 45* angle to the blade length to smooth out anything the orbital sander might have done. I barely took off little, if any, wood during the refinish. All of the dust was old varnish and paint.

I made a crude prop balancer out of some bars of round stock I had sitting around. I clamped two of them, parallel about 6" (prop hub thickness apart) and cantilevered them off the edge of the level Table Saw. Then another round rod through the prop hub and it would roll back and forth. the cantilevered rods were probably 3' of stick out, just enough so the prop wouldn't hit the table saw.

If I were to do it again, I'd probably just buy something like this wheel balancer. With my balancing method, the cantilevered bars did bend a bit at 3' stickout (1/2" diameter round stock I think). Between that and the table saw maybe not PERFECTLY level, it was hard to judge weather the prop movement was from being out of balance or it was just rolling towards of from the saw. I was able to get it to within a half a post-it note between the two blades though by adding more or less black paint to the backside of the lighter blade.

The paints I used weren't fancy... Rattle cans of Rustoleum Flat Black on the backside and I think Semi-Gloss on the front. It's probably what I had on hand...

Thank you all for your ideas.

I ended up buying a can of Varathane Ultimate Spar Urethane, Oil Based, at Home Doopa.

Cleaned the trailing edge with microfiber and then a tack cloth. Used a foam brush to apply a very light coating to the obviously bare areas, but also along the entire trailing edge. Lightly wiped up any excess with a clean cloth. 24 hours later I repeated the same process. Everything looks perfect.