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WB Primers, brushable; What is available now?

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WB Primers, brushable; What is available now?

Old 11-17-2015, 04:55 AM
  #26  
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You make some good points about cleanup, when not using the crosslinker.

I paint my color in a single day, so it's not an issue for me.

Painting the color in a single day increases adhesion between coats. You get a chemical bond. By painting a single coat, and waiting, sanding does become necessary, This is because you now are creating a mechanical bond, which is less desirable.
Old 11-17-2015, 05:24 AM
  #27  
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Originally Posted by 049flyer
GoNavy-,,,,,,,,,,,,,

Truly an interesting paint. Well worth experimenting with, would be awesome as a clear coat fuel proofer over latex or even decals, although I have not tried either myself. I have applied it on overlapping Monokote seams to seal against oil creep and it has worked very well in that application.
Two examples of latex with clear satin finish, Systems Three clear with cross linker, same type water based poly-u with cross linker as the Nelsons I've been told.
http://www.rcuniverse.com/forum/seap...-15-years.html
http://www.rcuniverse.com/forum/ques...l#post11975734

p.s.
the kingfisher flies on 20/20 glow fuel, the glow doesn't harm the paint one little bit
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Last edited by scale only 4 me; 11-17-2015 at 05:26 AM.
Old 11-17-2015, 07:05 AM
  #28  
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Beautiful airplanes. I especially like the Zero, not modeled near as often as other warbirds like the ubiquitous P-51. The lines of the Zero make me think it was a very easy to fly and forgiving airplane.

I think I am the only modeler in the world that has NEVER owned a P-51 model!
Old 11-17-2015, 07:21 AM
  #29  
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So4me: Very nice.
What primer did you use? Did you spray it or brush it? Did you sand it dry or wet? Are these fiberglass cloth over balsa?
Did you add anything to the latex (acrylic) paint, like Floetrol? Did you apply the paint by brush or spray?

I have a request: Take (a small quantity) of the Top Coat, and mix in an equal quantity of acrylic wb (latex) paint. Brush that onto a test piece, and after cure, subject it to glow fuel and tell me if it holds up.
Old 11-17-2015, 07:51 AM
  #30  
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Hmmmmm, this is interesting comment, from http://www.airproducts.com/~/media/f...y-overview.pdf, about the nature of one type of waterborne epoxy coatings:

In Type I systems, the curing agent not only crosslinks the epoxy resins in the final film, but in the liquid state often also serves as the emulsifier for the epoxy resin


Old 11-17-2015, 09:55 AM
  #31  
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Originally Posted by GoNavy
So4me: Very nice.
What primer did you use? Did you spray it or brush it? Did you sand it dry or wet? Are these fiberglass cloth over balsa?
Did you add anything to the latex (acrylic) paint, like Floetrol? Did you apply the paint by brush or spray?

I have a request: Take (a small quantity) of the Top Coat, and mix in an equal quantity of acrylic wb (latex) paint. Brush that onto a test piece, and after cure, subject it to glow fuel and tell me if it holds up.
I typically start with rattle can sandable auto primer, the kingfisher is all epoxy glass over balsa, yes., The Zero has a fiberglass fuse but the wings and tail feathers are covered in Monocote, then painted

Both were painted using an airbrush, I've tried all the tricks, but finally came to using straight water for thinning,

I've already tested it with straight 30% nitro car.truck fuel as well as flying it with 20% the last couple seasons, it works. When raw fuel gets on it does change the sheen, but once it evaporates it looks like new again
Old 11-17-2015, 01:10 PM
  #32  
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In the for what it is worth department, I tested a few wb clear coatings to see if they might be fuel proof:
Cabot wb polyurethane, AquaCoat wb hard acrylic lacquer with crosslinker, AquaCoat Table Top acrylic/polyurethane;
Allowing 10 or more days to cure, none could handle 15% nitro 15 minutes lying on the surface, best was Cabot which showed little degradation other than permanent staining, the color of the fuel (pink). The nitro beaded very nicely on the crosslinked lacquer, but was significantly softened in 15 minutes. The acrylic/pu non crosslinked blend softened within 60 seconds.

Just an experiment.
Old 11-19-2015, 09:52 AM
  #33  
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049:

You mentioned that the Nelson's primer dries slowly, and you can apply two coats a day. Are you sanding before the second coat? How long do you wait before sanding? Are any directions/instructions provided with the primer, other than what is posted at the Nelson website?

I believe the primer is now light gray versus the former white. Does this affect how you apply color coats?
Old 11-20-2015, 07:10 AM
  #34  
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Scale, do I understand right that you have used Systems 3 as a clear coat over latex? I'm doing up a little biplane art project and was planning to do it all Systems 3, but if latex works well as a color coat it would be cheaper and easier to do it that way.
Old 11-20-2015, 08:06 AM
  #35  
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Yes, both planes posted above are painted with Behr Latex with Systems 3 satin finish clear w/crosslinker
Old 11-20-2015, 08:45 AM
  #36  
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I have found an acrylic (latex) primer that can be wet sanded: Rust-oleum Painters' Touch Ultra Cover. BUT I could not get it to level, even adding Floetrol. It takes a lot of sanding to remove the brush marks.

From what I read, it seems that many water based coverings require new application techniques and conditions, and a higher humidity level may be required to get brushed wb coatings to level. Right now my shop humidity is running 60%, at 68 degrees, maybe humidity too low, and/or temperature too high, to achieve leveling.

Others may be able to use these wb acrylic (latex) primers, but I am going to try the wb epoxies. These have much longer dry times:
System3 wb-155 (which I think is the primer sold by Nelson's): Tack Free at 77 degrees F: 4 hours, Recoat Time at 77 degrees F: 12-24 hours, Full Cure Time at 77 degrees F: 7 days

System 3 silvertip yacht primer (a two component like wb-155), recoat when dry (about 30 mins), full cure 1 day.

With both products, System3 recommends 3 coats. With both products, you are instructed to let the product fully cure before applying topcoat; So you should wait 7 days from last coat of wb-155, or 1 day with silvertip primer.
Old 11-20-2015, 04:07 PM
  #37  
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I only use the clear,,, its works well
Old 02-05-2016, 07:53 AM
  #38  
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Very interesting thread for me. thanks to everyone for the informative posts. I want to phase out dope, which is what I've used for most of my planes all my life. I don't like the fumes, and now I have a shop attached to the house and I want to be able to finish planes in the winter when I can't take them outdoors.

I'm rebuilding a crashed Big John bipe and trying several experiments with materials that don't make noxious fumes. The thread is here... http://www.rcgroups.com/forums/showthread.php?t=2589155 It is attracting just about zero interest so I will report on finishing here instead.

On balsa-sheeted foam cores, I applied Polycrylic directly to the wood. The wood is bonded to the cores with Gorilla Glue and I am certain it will not warp. I found it takes 3 coats to seal the wood to the point where I can cover with other materials. Pc raised the grain, but no more than dope does. I just sanded lightly with 320.

I used glass on the center section, for strength in the dihedral joint area. I put it on with Polycrylic. No mess, easy to apply. Then I used strips cut from a paper bag to simulate ribs and applied with white glue. Then I put silkspan over each entire wing using Polycrylic. It looks fine so far. The silkspan/Pc surface is far from smooth, but I do not plan on a show finish. If I did, I would mix Polycrylic with talc and put on a few more coats. For this old airplane I'm more concerned with weight than with a fine finish.

I built the ailerons from 1/16th inch balsa sheet and 1/8 sheet ribs. No core, so I was concerned about warping the wood using wb. I sprayed on two coats of shellac from a can, then Polycrylic, and then silkspan like the wings. I have no warps and it all looks good. Maybe the Pc would not have warped it, but I didn't take the chance. Nice thing about shellac is that it is alcohol based, so no dangerous fumes, yet no water either.

My plan was to put down a white primer, either Glidden Gripper or Nelson white primer, haven't decided which. Then I'll take a part of the crashed plane to Home Depot and get a color match in Behr latex, paint the wings and then clear coat with System 3 clear.

I'm not so sure about that last part now, because the fuselage and tail are all doped and I'm concerned that the look might be too different. I will definitely use a wb primer, but I still might go with dope one last time for the final coat, just so it will match the rest of the plane. I figure the dope will not attack the foam underneath because there will be so many coats of material protecting it.

Any thoughts, guys?

Jim

Last edited by buzzard bait; 02-05-2016 at 07:55 AM.
Old 02-05-2016, 05:04 PM
  #39  
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If you are concerned about warpage, you may want to try polyurethane. The oil based poly does not warp balsa, so no sealing is required.

I'm in the process of glassing a 121" Luscombe, using polyurethane and .5 oz glass cloth. This is my second usage of the products and I am pleased with the results.

In the first pic, the fuselage is glassed with polyurethane and .5 oz cloth. The second pic is a completed model that was glassed with polyurethane and cloth>
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Old 02-05-2016, 07:35 PM
  #40  
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Beautiful models! But I think oil base will not solve my problem of keeping fumes out of the house.

Jim
Old 02-05-2016, 07:41 PM
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Jim:

My thoughts:

Warping the balsa. I wouldn't expect the balsa sheeting, held in a death grip to a foam core by Gorilla glue, to warp, but I share your concern about what a product might do if it is first coat applied to balsa built up structures. I applied seven products to 3/32 x 3 x 6 inch balsa sheet and noted the results, summarized on the attached. (AQ x119 SS is sold over the web by AquaCoat, as a waterborne sanding sealer; MWPU is MinWax Polyurethane, solvent based, and I used their wiping version.)

I thought I might see some real distortion to the balsa sheeting, probably some "curling" across the 3 inch width,
but really the only distortion was what I have labeled "curving", meaning the long ends raised up from the surface on which the sheets, or, the opposite, that the middle of sheet raised off the surface while the ends stayed on the surface.

Only the Zpoxy finishing resin and the MWPU did not curve/warp the balsa before drying. Only two of them left the wood curved/warped after they had dried: the AQ waterborne sanding sealer (only after two coats were applied), and the AQ waterborne "lacquer" to use their label terminology.

Every one of them, with only one wiped coat, was sufficient to cause water drops to bead on the surface after the coating had dried.

Here is an upshot. Despite the permanent curving caused by a second coat of the waterborne sanding sealer,
if I used it after sealing the balsa with a single coat of nitrate dope, it caused no problems when I used it on built up balsa structure. I have found that the X-119 product, when applied after a single first coat of nitrate dope, fills the weave of .7 ounce fiberglass cloth in three coats (with a brush), and I like it. I have used WB Polycrylic and found I need 6 or 7 coats to fill the same weave, even if I have added talc to the Polycrilic. The X-119 can be sanded or recoated after 30 minutes to 1 hour so you can fill the weave in one day.

Like you, I want to get away from solvents that can give you a headache or do worse. To the extent that "smell" is an indicator, I subjectively evaluated the odor of the drying product as seen on the chart. As you can see, the fact that a product is waterborne is no guarantee it will not stink.

Waterborne primers. Every "latex" (meaning waterborne acrylic) I tried, except Rust-Oleum "Ultra Cover", would not withstand wet sanding. I could not avoid brush marks with any of them (save an aerosol product) even thinned with water or after adding Floetrol. I could do a little better with a foam brush, but that required I follow up, quickly, by "tipping" with a high quality "tipping" brush to minimize brush marks and bubbles. A waterborne white primer from AquaCoat was highly tolerant of wet sanding, but brush marks and uneven coat thickness meant you wound up sanding off most of what you put on, even on an otherwise very smooth surface. I hold out no hope for this type of primer.

I tried SystemThree Silver Tip Yacht primer, waterborne 2 part epoxy, with mixed results. It wet sands nicely, but once again I had brush mark problems, and overlaps etc using a foam brush. I will probably experiment with this further. It "cures" in about two days. It doesn't have the strong smell of other epoxies I have used, but the instructions emphasize that you must wear gloves to avoid skin contact.



Old 02-05-2016, 07:53 PM
  #42  
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Let me try that attachment again.
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Old 02-06-2016, 08:06 AM
  #43  
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Great tests and information, GN, thank you. I've wondered about Modge Podge, which came out well in your tests too, but have not tried it

Painting a single unbraced sheet is a severe test, which makes it very revealing. I suspect even nitrate dope would show some curling if you used a couple more coats.

Shellac smells a lot when sprayed out of a can, but the smell dissipates quickly. Probably I was smelling the aerosol from the spray and it drops out quickly. Brushed on it should be much less. On my light aileron structure it seemed to me that it sealed quickly, much like nitrate dope, but I didn't do the thorough kind of comparison that you did, so I'm not sure.

Since the solvent is just alcohol it doesn't worry me. A lot of people use Aquanet hair spray to stabilize glass fiber and other materials. I think it is shellac.

The down side to shellac is it has a fairly limited shelf life. If I decide to use it regularly I would buy the solid chips and dissolve it as needed. I think the spray can lasts longer than a regular can, but solid form is probably best.

Noticed Nelson doesn't offer a silver. I tried mixing artists' aluminum powder with Polycrylic and painting it on silkspan and fiberglass adhered to balsa with Pc. I just brushed on two coats and it looks quite promising. I think it would take 4 or 5 coats to look good. Photo shows the trial.

The other photo shows the Big John wings glassed in the center, brown paper bags strips glued on for ribs, and silkspan over the whole thing. Two ailerons are from the original crashed plane and the other two are the new ones made from 3/32 sheet. The original had 2 ailerons on the bottom and I'm adding two more for the top. Everything was done with Polycrylic, except the "rib" strips were attached with white glue.

Jim
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Old 02-06-2016, 01:02 PM
  #44  
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I'm surprised that you can live with the strong odor off shellac, and not the relatively odorless polyurethane.

I manufactured paint for years, and I still can't handle shellac. LOL

Last edited by TomCrump; 02-06-2016 at 01:04 PM.
Old 02-06-2016, 07:30 PM
  #45  
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I have never tried oil based polyurethane on my airplanes because we when we had our floors done with it we had to do it in the summer with a lot of ventilation and we were warned it was not safe to breathe.

I'm surprised you would consider shellac worse, considering the carrier is just alcohol. Yes, it has a strong smell at first, but I found the smell dissipated quickly, as I stated. I think it's safer than oil based polyurethane and I don't think the odor lingers nearly as long.

Jim
Old 02-07-2016, 03:14 AM
  #46  
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Just personal preference, I guess.
Old 02-07-2016, 06:14 AM
  #47  
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You certainly are getting great results!
Old 02-07-2016, 06:24 AM
  #48  
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Originally Posted by buzzard bait
You certainly are getting great results!
Tthanks.

I guess that I have an aversion to water based products, especially latex.

Polycryllic seams to warp balsa, unless it is sealed. Sealing is an extra step that I prefer to avoid. The polyurethane eliminates the sealing and, to me, the odor is minimal.

I like to experiment, and find polyurethane to be fuel resistant, too. The downside is that it takes longer to dry, and, when used as a clear coat, it tends to yellow with time.

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