GoNavy

My Feedback: (15)

I would like to know what waterborne/waterbased primers are available now for those of us who want to
paint our aircraft.

I found a short thread on this topic, from 2012: http://www.rcuniverse.com/forum/ques...-solution.html
But things are changing fast in coating technology.

From my perspective, I would like to use a wb primer, which could be applied by brush, for several reasons.

I would like to hear from you if you have used a wb primer, which one, and how it works for you.
(My current project is fiberglass cloth over balsa, with thermal span over open bays, with the final
sealing coats wb Polycrylic. After priming, I intend to use either Nelson System III wb polyurethane,
or KlasKote epoxy.

049flyer

My Feedback: (18)

Nelson has a nice water based primer. I have used it several times with great results, it's white instead of gray so it is great under light or dark colors. Sands very nice, fills and hides, but takes a few hours to dry so not as fast as laquer based primers.

GoNavy

My Feedback: (15)

Do you spray or brush the Nelson primer? Any problems?

GoNavy

My Feedback: (15)

I had sent an email to John about his primer, and here is his reply:

The primer is an epoxy and it is very pale grey. It is easier to apply as the 220 sanding requirement is not included. It cleans up with water and thins with water. High build and very easy to sand.

(The instructions for his paint say you must sand the surface with 220 grit paper before applying his paint, because it attaches by a mechanical bond)

raptureboy

Good old latex. Gripper primer by Glidden will hold onto any surface and can be tinted for your darker colors by the paint store.

GoNavy

My Feedback: (15)

Do you apply it by brush or by spray?
Have you finished over it with any paint other than latex? How did that work out?
Could you sand the latex primer ok?

049flyer

My Feedback: (18)

I apply all nelson paint with a brush, usually a foam brush with great results. My finishes look sprayed and clean up is a snap, plus minimal masking is required as there is no overspray. For fine trim lines I use a traditional brush.

Nelson paint is fuelproof when used with the crosslinker. Great stuff, easy to use, easy clean up with soap and water, no smell and tap water for the thinner.

Nelson paint is more expensive than latex but a little bit goes a long way. Can't beat it for a nice, easy fuel proof finish.

GoNavy

My Feedback: (15)

I have read your mini review of Nelson's on the other modeler website. I too would like to be able to do more of my finishing work in the shop where I build.
I tried Nelson's many years ago, and just couldn't make it work by brushing. I was working on solid surfaces. I recall a post from someone saying they could brush it ok on covering materials like Koveral, but not on solid surfaces.
You were successful with both conditions as I recall.
Maybe I need to do more experimenting.

GoNavy

My Feedback: (15)

At some point I believed that latex paint contained latex and that this was a rubbery substance that did not sand well.
So when I discovered new interior house paints that were "100% acrylic" I thought I could perhaps use that, that it would be sandable. Then I saw labels for such 100% acrylic paints reading "acrylic latex" and I thought that avenue was closed. Then I found the following answer to the questions about the difference between "latex" and "acrylic latex" paints:
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[TD="class: answercell"] "There actually is no difference between latex and acrylic paints because there is no latex in latex paints. Let me explain. All water based paints today are referred to as "latex", even though there is absolutely no latex rubber in the formula. Latex has become a generic label. The stain, water resistance and covering capabilities are achieved by using acrylic resins or vinyl . Better quality paints have more acrylic resins than vinyl. Paints with a higher percentage of acrylic resin cost more. Vinyl is much cheaper than acrylic and is often used to mix with the acrylic to keep the cost of the paint lower. If you have special needs that may require a superior or better adapted product, the best advise is to go to a professional paint store and discuss your situation with someone that can explain the chemistry and applications of better products."

If the above is true, then there is no rubbery latex in the paint to make sanding difficult. There are a number of these
100% acrylic wb house paints available from big names in US paint manufacturing industry. I don't imagine they will be fuel proof (unless, perhaps, one could add a cross linker) bit that only means one has to apply a fuel proof clear like KlasKote epoxy. I would spray that, but that means only one trip with the airplane to the spray booth.

Has anyone tried the new wb "100% acrylic" house paints on their models?


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049flyer

My Feedback: (18)

GoNavy:

What sort of problems were you having on solid surfaces? Perhaps I can offer some help?

The only real "problem" I am aware of is the poor hiding ability of some lighter colors, especially yellow. Applying a white primer helps this greatly.

Bear in mind that as Nelsons paint is water based it is probably not a good idea to apply it straight on to a non sealed balsa surface. I seal all balsa surfaces with 2 coats of nitrate dope before applying any water based product. After that it's all good!

One HUGE advantage to Nelson paint is that it seems to be able to be applied over anything and it's chemical resistance allows just about anything to be applied over it. Pretty cool!

I have not tried water based house paint for 2 reasons. First, they are not fuel proof and all of my hobby interests involve glow engines. Second, I have read that house paint stays soft for 30 days or more after application. Too long for me to wait to fly a plane just to save a few dollars on paint.

aspeed

Anybody ever try the two part water cleanup epoxies for garage floors? I did a small test for fuel proofing, on a piece of foam flutterboard that I wanted to make into an airboat. It seemed fuelproof, and fairly strong. Kind of heavy, but that is for other reasons. I just had some left over from the garage floor. Some of the paints take a tint. I am really against primers and top coats because of weight.

049flyer

My Feedback: (18)

Hard to beat a butyrate dope finish for light weight, but the harsh chemicals and fumes are a problem in a small shop.

I have been experimenting with using tissue for color and trim and then just water based clear over it all for fuel proofing. Very light weight and looks pretty good too. There is a knack in picking out the right tisue and applying it though. Still developing my technique.

GoNavy

My Feedback: (15)

049: My problem with Nelson's paint (15 years or so ago) was lapmarks, and if I thinned it, it ran all over. I had no spraybooth back then. I see from your review that you found a technique to apply it successfully.

All: Besides the killer fumes (I use a full face respirator now when I apply nitrate dope), the dopes take forever to fully dry. (On guitar finishing websites, they recommend waiting 4 to 6 weeks for lacquer to dry before buffing.) One of the reasons I want to get away from dope is because months after I applied paint, my nice smooth finish started to show wood grain irregularities as the nitrate shrunk.

The wb products I have used and am looking at, cure as opposed to just dry. There is a chemical change. Apply dope thinner to dry dope and it dissolves the dope. Apply the solvents that were in the wb product, to the cured product and nothing happens.

Epoxies cure. Polyurethanes cure. Acrylics cure. By adding crosslinker, wb finishes cure faster. Some are rated 90% cure in 48 hours.

049flyer

My Feedback: (18)

Go Navy:

Are you certain you are using Nitrate dope? The nitrate that I use dries quickly, certainly overnight. I use it all the time as a sealer to protect the wood from water based products.

Butyrate dope on the other hand DOES take a very long time to cure, sometimes years, sometimes never. This is why eventually, butyrate often shrinks and cracks.

TomCrump

Paints don't dry as fast as some think. If you can smell the fumes, when up close, it isn't dry.

I always thought that an agent was added for a curing process, like adding the hardener to epoxy. Nothing needs to be added to polyurethane and latex acrylics.. The solvents (water included) just evaporate. To me, that means that they dry.

If wood grain shows through a finish, it is because of insufficient surface prep, and not the fault of the paint. . A proper stabilization and sealing of the substrate is required..

raptureboy

Sands well, but I still prefer spray can primer, I have not used any other top coats but latex ( acryilc) both spraying and foam brushing works well. You will need to fuel proof with an oil base polyurethane or waterbase with cross link. I have used the latex on both fabric and fiberglassed aircraft.

GoNavy

My Feedback: (15)

Good to hear that.

GoNavy

My Feedback: (15)

I just laid down a coat of Kilz 2 primer on a test section, by brush. I thinned it 10% with water thinking that would help it to level out before drying. Any bubbles released, but you can see every brush stroke.
I was applying it the way I have applied a half dozen water based acrylic and poly clears.
How did you apply it, and did it level out?

GoNavy

My Feedback: (15)

I laid down a coat of Kilz2 primer, unthinned. Leveling was no better.
Even after 48 hours it could not be wet sanded. I will not be using this.

I have an AquaCoat wb primer arriving soon and will try that.

Some of you may be interested in a web page, where the fellow (putting a colored finish on a cabinet), mixed wb acrylic colored paint with wb clear (he calls it "fortified paint"). From that page:

"Waterborne acrylic or polyurethane can be mixed with latex paint for a tough, durable finish that won't go gummy and sticky in humid summer weather like plain latex paint does. The finish will be the same color as the latex paint."

Here is the link:
http://thousanddollarshop.blogspot.c...e-sprayed.html

He includes photos.

Query: Could this be the holy grail for nitro builder/flyers; Paint with 100% acrylic (latex) house paint, mixed with a fuel proof wb clear, by brush if desired, ending up with a low cost glossy color paint job?

Yesterday I mixed some wb enamel, and a wb 100% acrylic exterior house paint, with 1) AquaCoat wb table top clear (self crosslinking) and seperately 2) with Cabots wb polyurethane gloss clear. After those cure for a week, I will spot test the results with 15% nitro and see what happens.

The "fortified" mixtures leveled better than the wb paints straight out of the can.

jester_s1

It's not enough to just see if raw fuel will dissolve them. To be good enough to use on a glow plane, the fuel needs to be able to sit until it evaporates and leaves the oil behind for a week or two, and it needs to be able to handle exhaust residue left on indefinitely. If you blast it with exhaust and leave it for 2-3 days, you should be able to wipe it clean with no change to the finish.

GoNavy

My Feedback: (15)

049: I understand the Nelson primer is wb epoxy. Is it one part, or two part? Is a crosslinker used?

049flyer

My Feedback: (18)

It is a 2 part primer. The activator/crosslinker is different than that used for their color paint. The mix ratio is also much different. I would use it under lighter colors that don't hide very well.

I have had great results covering sheeted areas like fuselages with polyspan applied with Sig Stix-It or Balsarite. Then a coat or two of Nitrate to seal then Nelsons Paint from that point forward. If the finish will be white, yellow or orange, a coat of Nelsons Primer will help hide the grain if applied before the color.

At this time I am applying all Nelson paint without crosslinker except the 2 clear coats at the end which are crosslinked. This gives me much more flexibility in how fast to re-coat and also allows easier fixing of runs and overspray.

Here is my latest build, finished with Nelsons Paint applied with a foam brush. Trim applied with a bristle brush.

GoNavy

My Feedback: (15)

That's a good looking paint job.

I have been testing various approaches and coatings, and at this point favor, for applying fg cloth over solid surfaces,
a single thinned brushed coat of nitrate dope, allow dry overnite, no sanding or maybe a little 320 grit, lay cloth and apply wb sanding sealer 1 coat brushed, dry 1-2 hours, no sanding, 2nd coat brushed, 1-2 hours maybe light sanding 320 or 400, apply third coat by brush. This completely fills the weave of .7oz fg cloth -- better than 6 or 7 coats of wb polycrylic. Sand smooth after the third coat and ready for primer. I.e., can apply the cloth, and fill the weave in one day.

I have experimented with three wb primers, brushed and aerosol. All are acrylic. I am not satisfied with any of the three. The problem I have is wet sanding. In every case, even after overnight drying, I eventually wind up with something causing cuts or scars, as if something came loose and clogged the paper. I don't like the way the acrylic sanded dry. I have one more to test, but it's looking more like I will give up on the "latex" primers, i.e., acrylic.

How did the Nelson's two part epoxy primer apply/dry/sand? Smelly?

TomCrump

Epoxy uses a catalyst, which I believe is different than a crosslinker.

The crosslinker for Nelsons can go bad with age. If it were me, I'd add it every time I used their paint.

049flyer

My Feedback: (18)

GoNavy-
The Nelsons primer has very little smell at all and it thins with water and cleans up with water like the rest of their stuff. As for sanding, I don't wet sand, only dry sanding. I have read of other people having issues wet sanding latex primer so I don't think you are alone. Nelsons Primer is slow drying compared to lacquer based primer so be ready to only paint 1 or 2 coats per day, but you shouldn't need any more than that anyway as it has a very high solid content, it's a primer after all.

I never have been able to master the art of applying fiberglass cloth without making a horrific mess of myself and my shop while adding way too much weight to my planes. I am somewhat adept at applying tissue, silkspan, Koveral and Polyspan so I prefer those coverings.

I am in awe of you and Mr. Crump who I think also uses fiberglass cloth.

TomCrump-

Certainly crosslinker CAN be added for every coat, however by not adding it except for the last coats you gain a tremendous amount of control over the paint.

First of all you have 2 weeks to re-coat, crosslinked paint must be re-coated within a MUCH shorter time, otherwise sanding is required. My job makes it difficult for me to know for sure when I will next be free to apply another coat, having a 2 week window works well for me. Re-coat within 2 weeks and no sanding is required.

Second, NON-crosslinked paint overspray and drips can be easily cleaned up AFTER the paint dries with isopropyl alcohol. Crosslinked paint is impervious to just about anything a modeler is likely to have in the shop, including straight dope thinner.

Third, left over non-crosslinked paint can be returned back to the original container without problems.

Fourth, I have done a quick test of chemical resistance of the NON-crosslinked paint after a full 2 week cure and am astounded. I reported my test in my review in a later update. Basically I took a rag and soaked it with a chemical and briefly scrubbed the paint surface to determine if the paint would easily peel, come off or sustain damage to the gloss. The only chemical I could find that would affect the paint was the isopropyl alcohol, even the 100% Nitro I had wouldn't touch it!

By far the most interesting part of the paint is it seems able to be applied over just about any other paint and just about anything can be applied over it.

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.