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Author Topic: Sparying Dope With Zinc Stearate  (Read 1943 times)

Offline Joe Rice

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Sparying Dope With Zinc Stearate
« on: April 20, 2011, 12:51:01 PM »
I have two coats of thinned nitrate dope brushed on my Twister and plan to brush on two more before applying dope with zinc stearate filler (from Randy) with an HVLP spray gun.  Does anyone have a recommendation on how much zinc stearate to use and suggested starting reduction ratio for spraying?   

Joe
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Offline Randy Powell

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Re: Sparying Dope With Zinc Stearate
« Reply #1 on: April 20, 2011, 03:56:53 PM »
Joe,

When I shoot filler coat, I usually mix up about 6 ounces of clear unthinned dope (I use butyrate), about an ounce of white dope and several drops of black dope to get a sort of medium gray with about 2 tablespoons of filler (Talc or Zinc Sterate), Then I thin it until I get it to spray gun shooting consistency. Since the dope I use is non-taunting Randolph's or Certified, the clear is the consistency of maple syrup. This mean thinning about 250% to get it thin enough to shoot through a gun. Mix it up and shoot some on a test panel. If it orange peels badly or you get sputters or glops out of the gun, shoot some thinner through the gun to clear it and add more thinner to your mix until the gun will atomize the material adequately to get it to lay down on the surface cleanly.

Hope that helps.
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Offline Joe Rice

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Re: Sparying Dope With Zinc Stearate
« Reply #2 on: April 20, 2011, 07:59:16 PM »
Quote from: Randy Powell on April 20, 2011, 03:56:53 PM
Joe,

When I shoot filler coat, I usually mix up about 6 ounces of clear unthinned dope (I use butyrate), about an ounce of white dope and several drops of black dope to get a sort of medium gray with about 2 tablespoons of filler (Talc or Zinc Sterate), Then I thin it until I get it to spray gun shooting consistency. Since the dope I use is non-taunting Randolph's or Certified, the clear is the consistency of maple syrup. This mean thinning about 250% to get it thin enough to shoot through a gun. Mix it up and shoot some on a test panel. If it orange peels badly or you get sputters or glops out of the gun, shoot some thinner through the gun to clear it and add more thinner to your mix until the gun will atomize the material adequately to get it to lay down on the surface cleanly.

Hope that helps.

Randy, Thanks for the guidance. That is the info I needed to start.  I plan to use nitrate all the way through until I shoot automotive lacquer based primer prior to auto base coat / clear coat finish. I  do not have butyrate clear, I guess I will have to forgo the benefit of tinting the filler coat. 
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Offline Randy Powell

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Re: Sparying Dope With Zinc Stearate
« Reply #3 on: April 20, 2011, 08:27:22 PM »
I might suggest that if you are planning to use basecoat/clearcoat system that you not shoot it on a lacquer based primer. It will probably work, but it could react. You'd be safer to use a catalyzed primer like pPg K-36 or similar. I'm just sayin'.....
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Offline Joe Rice

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Re: Sparying Dope With Zinc Stearate
« Reply #4 on: April 20, 2011, 09:05:20 PM »
Quote from: Randy Powell on April 20, 2011, 08:27:22 PM
I might suggest that if you are planning to use basecoat/clearcoat system that you not shoot it on a lacquer based primer. It will probably work, but it could react. You'd be safer to use a catalyzed primer like pPg K-36 or similar. I'm just sayin'.....

Randy, I have used PPG base coat over lacquer based primer on automotive spot-in work with no problems. Though would never do so on a full restoration and use catalyzed primers instead.  The photo is a Super Clown ARF where the fuse has been stripped and covered with silkspan, clear nitrate dope, auto lacquer primer (cheap Nason) and PPG base coat mixed to match the China Kote on the wing and stab.  There is some glare off the wing, but the spot in areas on the fuse are auto primer touch up with a detail gun...after the base coat was applied.  This ARF was a test bed for the material used. It has been in base coat for a year with no issues. I do need to finish it...

Joe
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Offline Randy Powell

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Re: Sparying Dope With Zinc Stearate
« Reply #5 on: April 21, 2011, 10:02:28 AM »
Joe,

I was thinking more of the primer gassing off under the urethane. I suspect that is you shoot lacquer primer and let it dry long enough, probably wouldn't have a problem. But it's something to think about.

Problem is, anytime you are using incompatible materials in a finish, you take a chance. Might be it will work great, but trust me as someone that has made many mistakes, they can jump up to bite you. I just shot a lacquer color coat over a lacquer substrate. I laid it on just a touch too heavy and got crinkling in a couple of spots. So now I'm going to have to go back and sand those areas down and go with several very light coats over a couple of days to build it back up. And I was using completely compatible materials. When dealing with lacquer, weird stuff is more likely to happen.
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Offline Joe Rice

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Re: Sparying Dope With Zinc Stearate
« Reply #6 on: April 21, 2011, 02:46:24 PM »
Quote from: Randy Powell on April 21, 2011, 10:02:28 AM
Joe,

I was thinking more of the primer gassing off under the urethane. I suspect that is you shoot lacquer primer and let it dry long enough, probably wouldn't have a problem. But it's something to think about.

Problem is, anytime you are using incompatible materials in a finish, you take a chance. Might be it will work great, but trust me as someone that has made many mistakes, they can jump up to bite you. I just shot a lacquer color coat over a lacquer substrate. I laid it on just a touch too heavy and got crinkling in a couple of spots. So now I'm going to have to go back and sand those areas down and go with several very light coats over a couple of days to build it back up. And I was using completely compatible materials. When dealing with lacquer, weird stuff is more likely to happen.

Randy,   Yes...that primer did dry a long time... I may have been lucky on this one.  You have convinced me to use a compatible primer.  I was hoping to stay away from 2k primers like K36 that require an activator.  I went to the local autobody store today and found a PPG shopline 1k primer, but it only comes in gallon.  I guess I will go with the K36 or one of PPG's Shopline 2k equivalents.  Do you have recommendations for application of K36?  I will be using a HF HVLP gun with 1.4 tip. 

Joe
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Offline Randy Powell

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Re: Sparying Dope With Zinc Stearate
« Reply #7 on: April 22, 2011, 02:43:32 PM »
Joe,

Maybe Mark Scarborough will chime in here. He has a lot of experience with catalyzed primers of different sorts. I've only used K-36. As to that, it's pretty cool stuff and once catalyzed give you an inert layer between incompatible materials which isn't a bad thing. When I've shot K-36, I've just had to be careful about viscosity. Normally not a problem as the stuff when mixed with hardener is pretty thin already and would go through a primer gun with a 1.4 tip easily. Try it out. If you get some orange peel or uneven lay down, just hit the primer mix with a bit of urethane reducer and it should be fine. Shoot a test panel first a see what you get.

Spray guns are funny sometimes. With the primer gun I use, I can pump some pretty thick stuff through it and it seems to lay down fine as a rule (depending on humidity and temp). I seldom have any issues shooting primer. The color gun I use is very sensitive about paint viscosity. Took me awhile to get used to knowing both how thin to make the paint to get a good, even layer and get the paint to lay down evenly and get the gun adjustment just right for the material mix. It's a decent gun, but takes a bit of futzing around every time I use it to make sure I'm getting what I want. The clearcoat gun I use for topcoats seems a lot less touchy about that. Of course, it's a lot more expensive gun than my color gun, but it seems like most anything within reason I put through it just lays down nice and flat. Of course, I've had that gun a lot longer and am used to it.As I say, guns are weird. Very individual.

K-36 sands very easily. Since you are trying to use it as an intercoat, try to resist sanding all the way through it. It's pretty easy to see when your are getting close though and you can sand it very thin without going through.
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Offline Joe Rice

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Re: Sparying Dope With Zinc Stearate
« Reply #8 on: April 23, 2011, 05:48:51 AM »
Thanks for the advice, Randy.  You have been a great help in convincing me to go this route as well as providing the information I need to get comfortable with the process.  H^^ 

Joe
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Offline Bill Little

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Re: Sparying Dope With Zinc Stearate
« Reply #9 on: April 29, 2011, 10:47:32 PM »
Geez, guys, I don't get it........... so many problems when using just one "method" all the way through........  I gotta say, it doesn't seem to make any difference as far as having problems with the way you guys talk about things going wrong.

Joe, I have used lacquer primer, like you have, and used basecoat/clear coat over it with no problems.  My Argus which has been shown here in the past was done like that with no problems encountered, not even years later.  Of course, it had a nitrate base, butyrate high shrink on the open bays, lite coat sealer coats, ......

I also break the rules and shoot automotive 2 part urethane clear over dope and lacquer bases.  That paint job has only held up for about 15 years now....... and was second to Windy's Spitfire for the Concours at Flushing its first time out.

The only major problems I have had was using too much retarder in some acrylic lacquer while in a hurry.  That happened twice and I won't use retarder, or a very hot thinner, anymore! ;D

I was also told by The Man to use a very, very light gray for a blocking coat on everything.  That gray I make with either Certified butyrate white, PPG mixing base white acrylic lacquer, or Duplicolor Paint Shop white, tinted with Sig, PPG or Duplicolor Black (it just depends on which can I grab first).  They all mix together with no problems.  That also works....... ;D

I am beginning to believe that problems are caused more by application techniques than a mixing of materials.  I will admit that there are SOME rules to follow like never putting lacquer over enamel (unless you are VERY careful LL~ J/K ) nitrate over butyrate, or using Aero Gloss with anything else...... ;D

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Offline Joe Rice

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Re: Sparying Dope With Zinc Stearate
« Reply #10 on: April 30, 2011, 08:21:31 AM »
Quote from: Bill Little on April 29, 2011, 10:47:32 PM
Geez, guys, I don't get it........... so many problems when using just one "method" all the way through........  I gotta say, it doesn't seem to make any difference as far as having problems with the way you guys talk about things going wrong.

Joe, I have used lacquer primer, like you have, and used basecoat/clear coat over it with no problems.  My Argus which has been shown here in the past was done like that with no problems encountered, not even years later.  Of course, it had a nitrate base, butyrate high shrink on the open bays, lite coat sealer coats, ......

I also break the rules and shoot automotive 2 part urethane clear over dope and lacquer bases.  That paint job has only held up for about 15 years now....... and was second to Windy's Spitfire for the Concours at Flushing its first time out.

The only major problems I have had was using too much retarder in some acrylic lacquer while in a hurry.  That happened twice and I won't use retarder, or a very hot thinner, anymore! ;D

I was also told by The Man to use a very, very light gray for a blocking coat on everything.  That gray I make with either Certified butyrate white, PPG mixing base white acrylic lacquer, or Duplicolor Paint Shop white, tinted with Sig, PPG or Duplicolor Black (it just depends on which can I grab first).  They all mix together with no problems.  That also works....... ;D

I am beginning to believe that problems are caused more by application techniques than a mixing of materials.  I will admit that there are SOME rules to follow like never putting lacquer over enamel (unless you are VERY careful LL~ J/K ) nitrate over butyrate, or using Aero Gloss with anything else...... ;D

Big Bear

Bill,    H^^  I appreciate the expert opinions all have shared with me.  I do have stuff on hand that can work as you suggest.  I am headed to the OBX for some fishing, so have time to make the decision.  Hey... I use to live in Cary... do you know Bad Andy Patterson?.  He go me back into CL when we flew RC in Johnson County.

Joe
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Offline Bill Little

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Re: Sparying Dope With Zinc Stearate
« Reply #11 on: April 30, 2011, 02:19:26 PM »
Quote from: Joe Rice on April 30, 2011, 08:21:31 AM
Bill,    H^^  I appreciate the expert opinions all have shared with me.  I do have stuff on hand that can work as you suggest.  I am headed to the OBX for some fishing, so have time to make the decision.  Hey... I use to live in Cary... do you know Bad Andy Patterson?.  He go me back into CL when we flew RC in Johnson County.

Joe

HI Joe,

Yep, I know "Bad" Andy real well! LOL!!  Along with Joe Owen and Bill Jedlica.  I was supposed to go to Huntersville this weekend for the meet, but things fell through.

Where are you located now?

Bill
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Offline Randy Powell

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Re: Sparying Dope With Zinc Stearate
« Reply #12 on: April 30, 2011, 03:40:04 PM »
Bill,

I've done all kinds of crazy paint stuff that worked. Sometimes it does. I've used acrylic enamel over lacquer with urethane on top and got it to work (though it was interesting). It's just a case of percentages. If you use the same material from the wood up, you are more likely to have things come out well. If I lived in an area that had low humidity and I could always shoot paint at 70 degrees then I doubt I'd ever have much problem using all lacquer. But even using compatible materials, shooting paint in less than perfect conditions (where I live most of the time) is a crap shoot. I don't need to compound it with incompatible stuff.
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Re: Sparying Dope With Zinc Stearate
« Reply #13 on: April 30, 2011, 11:22:01 PM »
Quote from: Randy Powell on April 30, 2011, 03:40:04 PM
Bill,

I've done all kinds of crazy paint stuff that worked. Sometimes it does. I've used acrylic enamel over lacquer with urethane on top and got it to work (though it was interesting). It's just a case of percentages. If you use the same material from the wood up, you are more likely to have things come out well. If I lived in an area that had low humidity and I could always shoot paint at 70 degrees then I doubt I'd ever have much problem using all lacquer. But even using compatible materials, shooting paint in less than perfect conditions (where I live most of the time) is a crap shoot. I don't need to compound it with incompatible stuff.

HI Randy,

I totally understand, but even using the same materials will lead to problems at times as you often encounter it seems, so.......... ;D

The humidity here is killer most of the year, so I have the same problems with lacquers. I had a friend who did the 5 figure and up custom paint jobs, National Show winners and such..  he used lacquer based primer for basically everything since basically anything will go OVER lacquer.  So far, I have not seen a paint that attacks lacquer primer.  Epoxy primer would probably be the very best, but it is too heavy for my tastes.  We are shooting the race cars with single stage urethanes and sometimes do use epoxy primers.  But for touch ups and repairs out comes the lacquer primer.  NASCAR race cars are extremely well finished, and not that many wraps are being used anymore.

I will admit.  I do not spend as much time on each plane's finish.  I have only done a few over my lifetime that I really took extra effort on.  Those were, if I say so myself, about as good as any.  And I have seen a couple of the NATS 20 pointers.  but funny thing is, many of the others are not very far behind...........  it is simply a matter of patience, effort, and time.  None of which I usually have in abundance when it comes to toy airplanes. ;D

Bill
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Offline Joe Rice

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Re: Sparying Dope With Zinc Stearate
« Reply #14 on: May 04, 2011, 09:41:53 AM »
Quote from: Bill Little on April 30, 2011, 02:19:26 PM
HI Joe,

Yep, I know "Bad" Andy real well! LOL!!  Along with Joe Owen and Bill Jedlica.  I was supposed to go to Huntersville this weekend for the meet, but things fell through.

Where are you located now?

Bill

Bill, I am in Manteo NC (Pirates Cove) now, but primary residence is near Peoria, Illinois. 

Joe
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Offline Randy Powell

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Re: Sparying Dope With Zinc Stearate
« Reply #15 on: May 04, 2011, 09:45:22 AM »
Bill,

It's more an issue of not complicating things. This current airplane has been blessed as far as stuff working (except for my own mistakes - but the paint has worked wonderfully). Part of that has been a bit more care in choosing times to shoot paint and a long needed de-humidifier in the shop. That has helped enormously. Fun stuff.
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