finishing

HI folks,

Anybody had experience finishing with pPg or other auto finishes? I've been working on a car and used this stuff. Seems like it would be heavy.

Any thought?

I used PPG car paint successfully (2nd row at the Nats on my second plane) on both stunt planes I built. The particular type I used is not fuel proof (I sprinkled the plane again this afternoon; it's getting ugly). Everybody else is using Brodak. Get on the bandwagon.

I have used Acrylic Enamel in the past with good results and it was fuelproof. Do not use Acrylic Polyurethane as in my experience it is not fuelproof. It took a nice spot of finish off of my truck that I had used it on when I set a combat plane on the hood with fuel dripping.

The key to any of these is in the preparation of the base and to use as thin of a coat of color as possible to keep down the weight. If you attempt to use the 2 part stuff, it is mean, viscious, evil, unless you have the proper breathing equipment. And if you use something that isn't fully fuel proof, you are in for a different type of trouble. I am with Howard--use Brodak dope and you will be happy with the finish. Didn't see the color you wanted? Here is where you can go to the auto paint supplier and get just the pigment only for the acrylic lacquer. Put this in clear Brodak dope, and add pigment, testing periodically, until it gets chalky. That's too much. Add a little more clear dope to the mix and you should be ready to paint. Matt did that with his 99 ship when he wanted a desert sand color scheme, and it worked fine. More than 400 flights and a year later and it still looks almost like new.

Howard,

I haven't "jumped" on the Brodak bandwagon mostly because I have a source to get straight Randolphs in gallon increments for $30 to $35 a gallon. I can get the blue or pink tinted stuff (binder and topcoat respectively). Brodaks is pretty expensive compared to what I can get Randolphs for. Hey, so I'm cheap. More than that, the straight Randolph aircraft grade lacquer is about the consistancy of maple syrup. Thick maple syrup. You have to cut it about 4 or 5 to 1 just to get it to the consistency of normal Sig or Brodak. The you cut it again to spraying consistency. You need a lot of reducer, but a gallon goes a VERY long way.

Now comes the new problem. I've been using a stock I've had of DuPont 3608 as reducer and that's just about gone. I suppose I'll end up getting Brodak's Thinner and Retarder. Should work fine as long as I use just it from start to finish.

Leonard,

I've just finished doing some testing using Randolph aircraft base (binder) mixed with acrylic toners from the art store. You know, the stuff they sell to artists? A DuPont chemist I met told me it's essentially the same stuff as the auto toners. Anyway, I mixed up some yellow, red and blue (about a pint each) and did some tests. The base color coats come out flat. Kinda like using a basecoat/clearcoat with catalyzed polyurthene. But putting on Randolphs topcoat (the pink tinted stuff) brought the shine right up. It really looks pretty good. I'll have to experiment a bit with mixing the colors I want. I found a DuPont autocolor mixing chart by weight and I'll mess with it some and keep a record book of weights.

Hey, it works. And based on my recent tests, this is what I'll use for the forseeable future.

My question about using pPg or other catalyzed polys was more about alternatives. The stuff I just reapaired a car with was incredibly easy to work with and you really had to work to get it to run or sag. Very nice stuff except it's about as toxic as plutonium. Isn't that always the way?

>auto toners. Anyway, I mixed
>up some yellow, red and
>blue (about a pint each)
>and did some tests. The
>base color coats come out
>flat. Kinda like using a
>basecoat/clearcoat with catalyzed polyurthene. But
>putting on Randolphs topcoat (the
>pink tinted stuff) brought the
>shine right up. It really
>looks pretty good. I'll have
>to experiment a bit with
>mixing the colors I want.
>I found a DuPont autocolor
>mixing chart by weight and
>I'll mess with it some
>and keep a record book
>of weights.

Randy;

Was your conclusion to use just the pink throughout, or use the blue as the base and the pink for the final coats?

I am embarassed to say just how old my supply of Randolph's dope is. Needless to say, my nitrate is in a blue can, and my butyrate is in a orange can. I think I've had this supply for about 20 years. My butyrate is running out, so I will need to come up with something else. I am very interested in your results and technique.

>HI folks,
>
>Anybody had experience finishing with pPg
>or other auto finishes? I've
>been working on a car
>and used this stuff. Seems
>like it would be heavy.
>

I haven't used the colors (although several locals have), but I have used PPG DAU75 with DXR-80 hardener, and it is absolutely excellent. Very easy to spray, easy to rub out in the first few weeks, and completely bulletproof. Similar base-coat/clear-coat systems have similar characteristics.

Another nice thing is that it will go over anything without messing it up. After having used SuperPoxy colors, I would expect that the car colors would not be too heavy. But you do have to put on much less, as it has way more pigment than dope. My graphite/nitrate:2-part epoxy color: PPG clear finish weighed around 5 oz total from bare wood. It also has a bunch of pinholes, but it wasn't because of too little paint!

Phil Granderson used some of the new type clear over Brodak colors and it came out front row good. I think this will be my plan on the next airplane, too, Brodak is easy to work with, but it isn't very fuelproof at all compared to the automotive 2-part clear.

Heed well Leonard's warning - all of the two-part paints are very dangerous (although so is most anything to one degree or another, dope included) and should be used only with skin/eyes covered and a very good 3-stage paint mask, or external air supply system. The danger with the synthetic is not so much the dain brammage, but coating your lungs with plastic. Dope is safe enough in thus respect, but has the expected solvent absorbtion problems. In either case, a good rule is that if you can smell it, you're getting too much.
Brett

I have used automotive finishes on the last four or five planes that I have built and have found them to be easy to use, durable and quick (heavy on the quick!). I have learned the secrets of this "black art" from my flying buddy, Bill Wilson, who has been in the paint and body business for 35 years. He uses the base coat-clear coat system. With this system you can cut the time of painting your plane from 3 weeks to 1 day. He has helped Mike Scott, winner of advanced at this years Nats, and also shot the final clear coat on Al Rabe's "Bearcat" that he flew at VSC this year. As far as weight is concerned, it is no heavier thana dope finish but there is the potential to put on more clear than is necessary as it is hard to believe that you could be finished so soon. And, yes, this paint can be dangerous to breath but so can water if you inhale too much of it. This system is not for everyone but I will never go back to dope.

Hi guys

Can I ask that, particularly on matters like finishing, we do not get too insular. Brodak dope, as good as it may be, ranks alongside 'unobtainium' that fabulous compound that makes all metals work in all applications beyond our wildest dreams.

I've done my homework, as have others, but the Hazchem regs places Brodak dope beyond the reach of anyone flying CL in Australia. Neither Brodak nor Randolph seem interested in manufacture under license so the rest of the world cannot have Brodak dope.

The real strength of our sport remains with those who maintain a global view. Bagging one readily available product because it not 'the best' in one market is the easiest way of losing supporters.

On the other hand, if anyone out there can find a way that we of the Antipodeas can get to use Brodak dope at a price less than the national debt, we who will benefit will salute you.

Cheers

>so soon. And, yes,
>this paint can be dangerous
>to breath but so can
>water if you inhale too
>much of it. This
>system is not for everyone
>but I will never go
>back to dope.

I've seen a lot of mention on using this paint system, but have never read a step by step "How-To". It could be out there and I just missed it.

If you ever get the time, I know that many of us would benefit if you would post your procedure. Reducing finishing time from a few weeks to one day (not including prep - obviously) is a very interesting prospect.

>I've seen a lot of mention
>on using this paint system,
>but have never read a
>step by step "How-To".
>It could be out there
>and I just missed it.

Well, if you go to a friendly auto paint store, the will give a flyer on each product. This includes almost idiot proof instructions on mixing the base and catalyzer, application including sprayer setting and times to work, etc.

I must say the primer I used is very high in solids and sands pretty easily. I really liked the stuff.

The only real trick, I think, is you spray the base coat (color) and then you have a finite amount of time before you must spray the clear in order to get a good bond between the base and clear. (ever seen late 80s Ford with pealing clear coat?) If you use a multi-color paint scheme, this may mean you need to shoot a color then put clear on it, shoot a color and shoot clear, ad nausium. I haven't tried it yet.

What's your experience, Brett? Do you get good adhesion between the color and clear if you don't spray the clear within 60 minutes? My trusty direction sheet says that in order to get decent adhesion between the color and clear you must spray the clear within a hour, before the base is completely dry. But this may not really apply for a finish that isn't going to have to withstand the beating a car does. Any thoughts

I've used the stuff a lot painting cars (yet another hobby). Done maybe 6 cars with it including some fairly involved paint schemes. But I've just shot the base color, then clear, the masked and painted trim color, then clear, etc. Since weight isn't a consideration, never thought much about it.

>If you ever get the time,
>I know that many of
>us would benefit if you
>would post your procedure.
>Reducing finishing time from a
>few weeks to one day
>(not including prep - obviously)
>is a very interesting prospect.

The stuff is pretty easy to work with. You have to make a real effort to get it to run or sag. Really good tacking. Once the catalyst goes off, it's fairly hard but may take a day or so to really get solid (unless you want to put your plane in an oven at 140 degree for 20 minutes). You just follow the mixing directions for each product. The primer I used was 2 to 1 base to catalyst. The paint just used a "reactive reducer" (thinner with a catalyst in it) and the clear was 5 to 1, base to catalyst. The stuff isn't real touchy about exact amounts for mixing. I used a scale to mix it, but the auto-paint guys tell me you can just about eyeball it and as long as it's relatively close, seems to work fine.

2 notes. First, clean your gun IMMEDIATELY after shooting. Remember, the catalyst will set the paint in the gun too and it's a real pain to get it all cleaned out if you allow the catalyst to go off while there is paint still in the gun. Second, treat the stuff like it's active plutonium. It's really, really, really toxic. Wear your charcoal canaster filter mask even when mixing the paint. The fumes are toxic. A particulate make doesn't do it. Unlike lacquer, where there is more concern over inhaling airborn paint, the fumes with this suff will get you. Once it's catalyzed and dries, it's pretty inert so sanding isn't really a problem (now you can wear your particulate mask), but prior to that, you realy need to use a good quality charcoal filter mask. Goggles too, if your eyes are at all even a little bit sensitive. The masks aren't cheap (mine was about $100), but I can tell from experience, you absolutely do not want to, at any time, breath this stuff. It can kill you and that's a fact.

OK, sermon over.

Randy

BTW: The stuff's not cheap either. It's the clearcoat that can really cost you. I think I paid about $15 for a quart of the primer, another $15 for the catalyst for the primer. The base coat (color) was about $25 for a pint (but that was a custom mix) and about $10 for the reactive reducer. But the clear...oh my. It was like $85 a quart and $20 for the catalyst. Now, since you really only need one coat, maybe 2 of the clear, a quart goes a long way. But it can get pricey in a hurry.

Just a note on the toxicity of catalyzed enamels and the like, my father spent the last thirty years of his life as a bodyman/painter, never using any type of respirator (this was well before anyone really knew the dangers of catalysts) and ended up going blind, having two brain tumors removed after retirement, followed by months of radiation treatments and dying of numerous neurological problems that were directly attributed to these paints. Please don't take this stuff lightly, it is highly toxic.
Kiiski

Randy, it is not necessary to shoot clear between coats of color. Simply wait 15-30 minutes (depending on temp. and humidity) and you can tape and shoot the next color. The finite amount of time is the paint company's disclaimer. The color is quite porous and will soak up moisture and contaminants easily. I have kept planes with only color on them for up to a month in a clean zone (my bedroom) before shooting the clear. I reccomend using clears that have a minimum of a 4-1 mix. I also reccomend adding 25-50% more reducer. This will allow you to apply the clear in thinner coats so you will have more control of the amount of clear applied, as this stuff can be heavy if abused. Allow about 20 minutes between coats for flash and check to see if the gloss dies back. 48 hours of cure time will be enough for up to 15% nitro.

The paint company was claiming it had to do with adhesion of the clear to the color, but I suppose if you allowed contaminants to get into the pore of the paint...

I've used several differnt clears, from Imron (bad news, as far as I'm concerned) to pPg, Acme and this latest is "Omni" clear. Each had different recommendations as far as catalyst to base ratios. I do like the idea of using some sort of reducer to give you additional control over the amount of paint used. How does this effect dry time? Do you use the reactive reducer or something else? What?

You're right about not using too much. If you have sprayed a lot of lacquer, it's sometimes hard to remember that whatever you spray on with poly, stays on. With lacquer, a plane will actually get somewhat lighter as the finish gases off. No gas off with the poly. Being able to spray thinnner coats by further thinning the mixture would be great.

I have to admit to being stumped by the term "reactive reducer". As far as I know, the reducer is simply a thinner and the only reaction that occurs is the thinning of the clear. I would advise you to use the same brand of reducer as the poly although my paint "guru" assures me that any reducer that is not oil or water based is acceptable. I would also like to give you a tip that might help you keep the cost down a little. In most areas paint is classified as HAZARDOUS MATERIAL and the paint shops have to pay extra to have it disposed of by special collection firms. This means that most shops will gladly give you any unused paints just to be rid of it. The colors that you don't like make really good ant killer.

What about repairability? Obviously, the auto body guys know how to repair and patch these fancy paints, but they don't have to stick down a new patch of silkspan (etc), shrink it, dope it, and then refinish. A lot of what I've seen looked VERY bad when repairs were required. So I'd consider repairability as an important quality. A certain B-17 pilot was raving so about Brodak dope that he was interested in building a model with a really outstanding finish for the next NATS...a comment which left me wondering just how much better that could possibly be!
Steve

Steve,

Good point. I haven't had to repair any. But then, the way I've been flying lately, most of my "mishaps" are pretty far outside the "repairable" range.

Hey Howard! How do you repair the stuff?

Aye, there's the rub. I've been wondering about that lately. I'll find out and tell you. I've amassed a bunch of dings that need fixing. Have you heard the story about the seam in the fin?

Howard,

I haven't flown much since my fiasco in Salem. I've retrofitted an old plane with an engine, but haven't tried it out yet.

What story about the seam?