View Full Version : Need covering advice

03-23-2006, 07:51 PM
Hi, On my experimental I am using the Poly Fabric system. I brushed the first coat of Poly Brush on as the book stated. Then I sprayed the first cross coat of two spray coats of Poly Brush on today. After it dried (to a glossy finish ) I noticed the finish has lots of defects meaning you can see a sag here and there, not a run but a difference in thickness enough that you can tell it. Brush marks ans also here and there a dribble of cement must have been on the fabric. And some specks which I assume are dirt . Should I spray my second cross coat of Poly Brush and then go ahead with the Poly Spray? Then sand the defects out when I get to the Poly Spray? I had a few edges lift , but ironing them seem to take care of them. Thanks

Dave Calkins
03-23-2006, 08:52 PM
Hi 160. I hope I can help.

Do you have the Poly-Fiber Manual?

Do proceed as they suggest.

That would be: ..... just use a clean cloth and some thinner to remove any lumps, bumps, or drips that are now visible. Then follow with heat smoothing, another coat or two of P-brush sprayed over the mistakes, and then keep going with the P-spray.

Make sure you have good light across the surface so you can see the flaws and catch them now, NOT after your silver P-spray coats. Major flaws must be dealt with before P-spray. Minor ones can be sanded out after you've built-up enough P-spray.

Good Luck.


I had to edit my earlier response because my reading comprehension must be TERRIBLE. Thanks for setting me straight Sharp! :roll: :-?

03-23-2006, 09:07 PM
I read it different...
Then I sprayed the first cross coat of two spray coats of Poly Brush on today
Seems like he needs to do the thinner clean-up, then additional coats of spray'd Poly Brush before going to silver.

03-24-2006, 06:35 AM
Get the polyfiber manual. Read it Read it read it. If they say to pee in the paint and stir it with a blue spoon DO IT. Their tech support is awsome. I emailed them with a question on Labor Day and got a response in an hour. It is not hard to get good results.. Just take your time and read. All the problems you mentioned are addressed in the manual. And polybrush does not sand out.

Start by cleaning your spray gun. I mean really clean.. take it apart and clean it.. If it won't clean up then pitch it and buy the best one you can't afford.

If you need to PM me and I can talk you through some of this.

Dave Johnson

PS I think I talked polyfiber into printing a centerline on there finish tapes.

Jon B.
03-24-2006, 07:51 AM
Snert said:

"Start by cleaning your spray gun. I mean really clean.. take it apart and clean it.. If it won't clean up then pitch it and buy the best one you can't afford. "

I'm not so sure this is a necessity. Buying an expensive gun, that is. Much of the Poly-Fiber 'stuff' I sprayed was with the el-cheapo gun that came with my compressor. Guns don't get much lower-quality than this. It worked out just fine. I also borrowed a worn out Sharp from a paint-shop friend. It's his 'primer' gun; the least-best one he owns. It worked just fine. I shot a bunch of enamel with it, too, both AeroThane and PPG (struts & such).

The beauty of Poly-Fiber 'dope' is that it can easily be fixed and re-shot if you screw it up badly. I didn't get any runs in mine 'til I started on the Poly-Tone color coat. Before they dried, I rubbed the runs a bit with my finger and sanded them smoth after the paint was dry.

Poly-Brush can easily be smoothed with a not-to-hot iron. An earlier poster is correct, it doesn't sand. Poly-Spray *can* be sanded but doesn't like a hot iron; don't touch it with one.

A rag and reducer (or MEK) works wonders for bad spots in Poly-Brush. The dope never really 'sets' so it can be wiped off long after it's dry.

Jon B.

03-24-2006, 10:54 AM
Thanks Guys, I have the Poly Manual and I have 3 spray guns, Binks and a Sharp HVLP . I have been spraying for 30 years. I also have a very good filter system . The question is unlike spraying a car where the finished spray is what you get, but you know what you are starting with ( a smooth sanded Primer coat ) . This Poly stuff melts into the next coat. The question is: Do I need to worry about the Hi- Lo differences I can see in the sprayed Poly Brush . If you take a rag to the surface to smooth up a sag or dribble you creat a low spot your eyes can pick up looking at it from differ angles. It seems to me the more you play with it, the more it will show later. That is why I question that you should only remove the major defects like a run. Then put enough P Spray on it to sand it smooth? Also do you guys spray only on the flat side. I called Poly Fabric and the woman there told me to spray each side separate. That would take about 14 days total for all the coats. Is this how you guys do it? Thanks Sam

Clay Hammond
03-24-2006, 11:12 AM
Wait till the end of the day for my brother to chime in, he has some excellent experience with Poly-Fiber having used it for multiple New Standard builds (read big airplane, lotsa fabric). I'm sure he will be able to help. Plus we are good friends with one of Poly-Fiber's part owners, so the "straight dope" is close at hand for us...... I'd try and help, but I generally just do what I'm told when in the shop.

Dave Calkins
03-24-2006, 12:02 PM
Good boy Clay!

160, if by "...spray only on the flat side..." you mean= lay the part flat and spray it that way, then wait 'til it's cured and flip it over........

Yes, spray it flat, but NO don't wait for 14 days. Build a rotisserie so you can spray it all at once. You'll be taking forever if you don't make a rotisserie.

As far as low or high spots, Yes, you may be able to see that stuff later. I'd consider an extra sprayed coat of P-brush. (Jon G. told me that an extra coat of sprayed P-brush doesn't detract from the results, it's simply a tiny bit thicker 'rubbery' capsule, making a nice, flexible "unit" out of the thing), Then your build-up coats of P-spray (silver) and sand out any flaws still visible. Make sure your tape edges are down before you go to P-spray. Also, wet sanding the flaws visible in the P-spray (silver) is easy. Have lots of water available so your paper doesn't 'clog', and only make a few swipes on any surface followed by cross-coat build-ups of P-spray before you sand again.

This stuff is all in the manual, and, having done this many times, I can say the manual tells it like it is.

bob turner
03-24-2006, 02:09 PM
My first attempt was unassisted, and done with a ten-dollar hobbyists syphon-feed gun. No problems with flaws, and I brushed the first two coats, just like they recommended in 1968. I didn't really care for the Poly Spray back then; it was full of trash and brittle. It is a lot better now.

I have found that I like Nitrate/Butyrate better - it doesn't iron as well, but it sands a lot better. I like to see my face in my fabric finish, so I sand the first white coat almost completely off, then after enough yellow is on, I do the 400/600/compound trick. No runs, no brush marks, pinked edges barely visible. Not what I'd do if I were flying in the bush!

Dave Calkins
03-24-2006, 03:07 PM
My point above about sanding may not have been strongly enough stated. Especially after BobT. added what he said about "...sanding off most of the white...".

For the neophyte......The point is: The P-spray (silver) sands very easily. When you sand it, you MUST NOT sand through it and into the P-brush and fabric below it. It's not a problem if you only take a few swipes back and forth in an area, then move on. If you over-sand, you will have made a bunch more work for yourself because oversanding raises a fuzz from the fabric and you will have to get the fuzz back down with P-brush followed by more build up of P-spray.

Moral: Don't over sand. Just a few swipes will handle the first sanding. You'll then build-up more silver and knock it back with a few more swipes.

I am a wet-sanding hater. I don't like it. But, I enjoy doing it on Poly-Fiber because it's easy to do and ensures a very nice end-result.

I like Poly-Fiber. DAVE

Steve Pierce
03-25-2006, 07:41 AM
I would MEK the glue spots and reapply the Poly Brush. The slight irregularities in the Poly Brush can be sanded when you shoot Poly Spray. Get it the way you want it before you shoot Poly Spray though. Use parchment paper to iron out irregularities all the way through Poly Tone. However at 240 degrees be sure and let the paper cool before you pull it off. If you don't it will pull the finish off all the way down to the fabric. Don't ask me how I know. 8) You will learn a lot on your first cover job and can have fantastic results however you will do things different next time and have an even better finished product. The guys around my hanger say I am too picky and that no one will notice some stuff. The problem is I notice it.

03-30-2006, 07:15 AM
Hi Guys, thanks for all the ideas. I finally have the six coats of P Spray on the fuselage. 3 Cross Coats It's finally looking good . I agree that the second recover job a person could do alot better. Experience teaches a lot. Hopefully I won't have to do a recover job for a long time. I plan on using this plane, it's not a show plane. I will try to get some pix on the site . Leaving for Sun and Fun Saturday, Hope to get some more ideas and the parts to finish up my project . New Slick Mags, spinner and tail brace wires. I will be gone for a week, so pix may be a while.