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Using Koverall and Dope

Old 07-12-2002, 07:29 PM
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Default Using Koverall and Dope

Does anyone have any suggestions on using Koverall? I applied the Koverall with Stix-it, then used two coats of nitrate dope. Next was 3 coats of a mix of nitrate dope, talcum powder, and thinner. Then when I painted using Butyrate dope, I was still able to see the weave of the fabric. I would like to be able to paint it without seeing the weave. Many of the full scale aircraft use Ceconite which is a bit heavier than Koverall, and they also use dope, so how do they get it to look so good?
Any help would be greatly appreciated.
Thanks,
Kyle
Old 07-13-2002, 01:28 AM
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Default Using Koverall and Dope

From what I've heard, full-sized planes have to put on 5 coats of aluminum dope to prevent UV light from affecting the fabric. This is before applying color coats. Maybe this is what fills in the weave so much.
Old 07-13-2002, 10:25 AM
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Default Using Koverall and Dope

Kyle,

I don't know if you sanded between the three coats of filler or not, and I have not ever used Koverall, but have used Silk and Dope using the same method you have described.

Without sanding between coats the silk was impossible to fill. With a light sanding between coats the weave filled with three to four coats and the finish was lighter also. I used #400 wet and very light pressure.

I would have to beleave thar Koverall would fill very much like silk. Boy does this bring back memories I never liked the smell of dope so have not used it since MonoKote came out in about 1959-60.
Old 07-13-2002, 07:12 PM
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Default Using Koverall and Dope

Yes I did sand after the filling dope. I believe I used 600 grit dry though.
Kyle
Old 07-14-2002, 06:01 PM
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Default Using Koverall and Dope

The planes ,that have the glass smooth finish when they are painted ,are sanded inbetween each coat or so of paint. As you sand back the paint( never deep enough to cut into the fabric and clear) the weave gets filled as you knock down the paint. you stop when the weave is filled plus a couple of coats. After the color is solid then with the right grit rubbing compound you polish the surface. It gets shinner and shinner as the sanding scratched are rubbed away. Many times thes is done to a clear top coat over the color. The control line stunt guys are masters of this. Dope is a laquer type paint very thin in pigment because it uses evaporation to dry. This si the same thing if you hear a hotrodder say he has a 20 coat hand rubbed finish. 20 coats but after each coat it is sanded so only a little stays each time.

Tom
Old 07-15-2002, 12:06 PM
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Default Using Koverall and Dope

Kyle

Tom is correct when saying that you must sand between paint coats also. When sanded correctly the high spots are sanded down and fresh paint coats will eventually fill all low spots thus no weave shows through, sanding makes this happen sooner and keeps weight down.

Also, I may be wrong but I think the C/L guys use silk span which is more like tissue than silk (not woven) and fills much faster. This was true when I flew C/L Stunt in the early 50s and I can see no reason for them to change why fix what's not broken?
Old 07-15-2002, 01:26 PM
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Default Using Koverall and Dope

Any clear dope, even nitrate will take 8 to 12 coats to fill light weitht silk, and Koverall is much thicker. However, with a color coat it may take as little as two coats. Light weight silk is easier to fill than medium weight silk span, but it takes more than light weight silk span. Typical stunt paint procedure for medium silkspan is, two to three coats of clear nitrate dope, one or two coats of acrilic auto primers, sand lightly, three coats of silver butyrate dope or two coats of silver acrilic laquer, sand until primer shows and recoat with silver repeat untill glossy smooth, three to six coats of color butyrate dope or one or two coats of acrilic laquer sanding with 600 or higher grit between each coat. I don't recommend using butyrate dope because you have to wait a week to sand without gumming up your sandpaper. If using laquer (or even dope) add some plastisizer to it or it will harden and crack in a few years unless you coat it with restoration solvent every year or two.

Obviously this is a lot of work! And with drying time of a week between sanding it will take several months! The competition stunt guys do this because they get 20 points for apperance, if they use the same plane the next year the points are reduced. While they are flying this season's competition on weekends, they are working on next season's plane. So longivity is not an issue.

Reccommend that you spay a coat or two of automotive lacquer, and finish with polyurethane or automotive paint. Actually the giant scale guys would probably know how best to fill the Koverall.
Old 07-15-2002, 04:47 PM
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Default Using Koverall and Dope

I don't think I can get auto laquer. When I asked my local PPG dealer, he said that it was discontinued because of of pad it is for you. Also, I hadn't wanted to deal with polyurethane auto paint. I have a friend who paints his heli's with PPG concept, and even with a good respirator he ended up getting asthma.
Bingo Flyer: I think that silk and silkspan puncture too easy for my purpose. I plan on using koverall on large aircraft.
Thanks,
Kyle
Old 07-15-2002, 06:02 PM
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Default Using Koverall and Dope

Maybe PPG doesn't sell laquer but it is still available, any auto parts store sells spray cans of the stuff, usually under the PlastiKote brand name. Be sure the can says it is acrylic as there is the same thing as nitrate laquer which is about the same thing as nitrate dope and it is not fuel proof. Pretty sure you can buy Dupont lacquer in cans at auto body shops.
Old 07-16-2002, 12:41 AM
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Default Using Koverall and Dope

Dupont still has laquer primer I think called fill and sand. It still is a body shop standard even though base/clear paint has taken over. Laquer is not as bad for your body as the base/ clear but it is worse for the enviroment because the sovents evaporate and go into the atmosphere. Base /clear is worse for you because the hardining ingreadent is the same as in CA glue. If you breath the mist the fog hardens in your lungs, and cant be removed, but is not as bad for the enviroment because it chemicaly hardens with little evaporation. Laquer gets you high! Laquer Paint is getting hard to find in states like California because of this. I What Kind of plane are you finishing?
Old 07-16-2002, 02:38 AM
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Default Using Koverall and Dope

In the near future I am going to finish a 1/3rd scale cub with this. The weave doesn't need to be fully filled in for this. Afterwards though, I want to finish a 1/3rd scale Laser with this. Also for the Laser I wanted to polish and wax the dope, so I wanted to practice these things on the Cub and other wing panels to develope a method that works well.
Thanks,
Kyle
Old 07-16-2002, 10:54 AM
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Default Using Koverall and Dope

Aircraft nitrate dope is the same thing as nitrate lacquer. Butyrate dope, nitrate dope, and acrylic lacquer can use the same thinner. Butyrate dope is the slowest drying because the butyrate plastic absorbs the thinner better. You can also buy Randolph's acrylic lacquer from Aircraft Spruce and Specialty, colors are limited though. Butyrate will last longer, especially on the fabric. But harder to sand unless you wait for it to dry for a week. Take your choices.
Old 08-28-2002, 01:30 PM
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Default Using Koverall and Dope

I believe the Sangyo Gunze Mr Colour range of colours for the plastic scale models people are acrylic lacquer. They come in all sorts of colours including military, but in small bottles.

Anybody has tried this paint on their models?

Chris
Old 08-28-2002, 02:00 PM
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Default Using Koverall and Dope

I doubt it, acrylic lacquer thinner will eat up stryene plastic somthing fearce. You may be thinking of acrylic enamal, same plastic but crosslinked with another polymer and with oil based thinners. (I think)
Old 08-29-2002, 01:18 AM
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Default Using Koverall and Dope

I used a laquer based polyurethane to fill in the weave of the 0.7 oz fiberglass on my TF Spitfire. It took 2 coats to fill the weave, then a third coat to make it smooth and ready to sand.

I mention this becuase I used Stix-It and Koverall on the control surfaces, and I plan to use the polyurethane to fill the weave on it. I expect to again only use 3 coats. The stuff I got is called Deft. I got it at Wal-Mart for $8 a quart. No sanding between coats and it won't kill you with odor. Don't use it in your bathroom, but it's not too bad

-Joe

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