lillbill11

hi everyone:

does anyone know what the trick is to painting and smoothing foam airplanes.

thank you very much for any suggestions.

yours truly bill gray

Technito20

There isn't really a trick to painting foam. Most people including myself just use water saluable paint from Walmart or somewhere. Just don't use some of those pressurized spray paints because the vapor may eat away at the foam.

blueberry

bill,

I use Krylon H2o it comes in a regular size spray can and is water soluable and odorless. I don't know what kind of foam you are painting but it works great on depron. Just try a test peice first.
As far as smoothing I've heard of guy's using light spackling compound (dry wall compound).
Again try a test peice!

Pete

TedShredz

Hi Bill,

Painting foam isn't rocket science, but there are a few things to consider if you're going to explore for solutions. I am assuming that you are painting an exposed beaded cell foam- where the foam surface was cut with a wire which left a somewhat rough appearance. Before getting into all this, consider the foam is softer than the filler, so the filler will sometimes flake off if the surface takes a dent. The paint will come off with it. Both the paint and the filler weigh something....is weight an issue?

I agree with the suggeestion using the cheaper hardware-store water based paints. Test the materials first (always do this!) on scrap. I found some water based spray acrylic that worked so well on beaded foam that now I'm looking for as many of the colors that the supplier has. Avoid the ones with toluene and acetones- it will definitely eat the foam....look at the ones with ether/ glycol propellants (at least the ones I have seemed okay), or the odorless types, but I'm not sure what the propellants in those are....

I have used some paints that contained enough of something (which chemicals I'm not sure) to cause the paint to remain tacky for a few days. This paint was okay after it finally dried and suspect that there was a minor amount of the (beaded) foam surface that "melted on contact" but it formed a skin to which the paint bonded very well. Just lucky (that time) I guess.....but sometimes "experimentation" (by deliberate act or by accident), with how you use whatever paint you have, will yield good results. If your paint has something in it designed to make it dry quickly (a flash agent/propellant) sometimes spraying the surface from farther back in lighter coats will allow most of that chemical to evaporate (flash) before it has a chance to "eat" the foam surface to any great degree, providing good surface bonding to foam. Experiment with what you have on some scrap materials- you might surprise yourself.

As for the filler (to deal with surface roughness), take your pick. The points I provided above do not take into consideration a filler media like spackle to which just about any paint will stick to. Considering that in most cases our hobby is trying to find a minimal weight solution to issues such as these, you should never have a layer of filler thick enough to safely use just any paint- stick to the foam safe (or controllable) ones . I looked for a light filler/spackle (one that can be sanded down quite (feathered) thin without cracking- drywall compounds should be fine as mentioned before) and found that they are available in big quantities at places like Home Depot. I'd advise wetting the foam surface you intend to do to get better penetration into the foam and keep the compound you use quite moist to penetrate as deeply as possible. Lay it on thin- it doesn't take much and you can always come back and hit it again later after the first sanding if you have to. Wait until it is completely dry before sanding (I left mine for >2 days in a dry location). When I sanded I used a sanding block made from a piece wood with a fairly dense foam rubber pad and some fine sandpaper. The foam rubber minimized any dents I might have inadvertently added to the project.(I was repairing crash damage on a plane with a non-removable wing. The foam had a radius did very nice wing roots up against the fuse). Tack cloth before painting if you wish.

The surface you are left with absorbs paint in a somewhat unpredictable way- even gloss paint might look flat or mottled after the first coat. Subsequent coats of the same paint will get a smoother appearance, but avoid putting it on too thick- areas that allow the paint to penetrate into the foam under the filler might swell/shrink/react differently and, if your surface is a beaded foam, these chemical reactions will leave your surface rough again. Remember to keep in mind that when your foam surface bends or takes a hit, the spackle and paint might not stay in there......

Before painting, I did something to help get the pressure up in the can- I filled a deep sink with warm water and warmed up the paint in the spray-can. I know there are warnings on the cans about doing this kind of thing, but I found that with this kind of paint it atomized and reacted faster than if I didn't. I'm sure the water temp never exceeded 100 F and I made sure I dried the can off and there was no water droplets on the outside of the can before I started painting.

The results I get are predictable and quite satisfactory- normally my 3D planes are not things of beauty to look at, but my future projects include more refined models that will not take the beating that the 3D planes do so going all out on a surface prep will be more practical. I've been thinking that I might try a water based polyurethane paint next when weight would not be a factor- it fills, it's sandable, durable, and it's closer in composition to the chemistry of the foam so maybe it won't flake off when it gets dinged.....but this is another experiement.



Play with this...have fun. I hope what I've offered helps.

Ted

lillbill11

THANK YOU VERY MUCH TO EVERYONE FOR ANSWERING MY QUESTIONS.

IT SURE HELPS A LOT TO HEAR FROM THE EXPERIENCED PEOPLE IN THIS FORUM.

MY PLANE IS A GWS TRANS-QUAD FOAMIE AND HAVEN'T FLOWN IT YET OR PAINTED IT.


THANKS AGAIN TO EVERYONE.

YOURS TRULY BILL GRAY

woodduck-RCU

Blueberry, thanks for the info on the Krylon!! Have you tried it on EPP foam such as a Wing?

Thanks

Wood Duck

blueberry

Wood Duck,

I have not tried it on anything except depron. My gues is it will be ok but try a test. Another thing that is nice about the H20 is that it will clean up with water. Krylon makes another one that is called Fusion says that it works on plastic I DON'T RECOMEND IT! It didn't eat the foam but it distorted it a little. Also it's not water clean up>

Have fun,
Pete

RickAvery

Just saw the H2O Krylon and picked up a can of red. Tried it on a test piece of EPS. Not a problem! There is a pretty good selection of colors also and at $3.99/can, a huge increase in value over the little weenie cans of Tamaya, $4.99 or Short cuts, $2.50 per can.
Rick

Giohwe

My Feedback: (1)

I've used H2O on FFF and it works nicely. Just remember, thin coats...

avatar71

is there any paint out there that will actually bond to the foam? My stryker uses taped elevons and if i'm not careful, the tape pulls the paint right off. I have used Testors Model Master Acril and Fascolor (terrible, actually washed off with water!)

blueberry

I use the Krylon H20 also. It adheres very well and is water soluable but should not wash off with water when it dries. I have also put decals on it and they did not peel any paint off but they also didn't stick very well to it. So I woul try a test peice with the tape.

Pete

avatar71

thanks!

rwcorleyze

Has anyone tried the Krylon H20 on the Elapor foam; such as Multiplex uses for the Easy Star? Trying to figure out how to change the not-so-hot blue wing color. some have said it's hard to get a good undercoating on the blue, it keeps bleeding thru ...

Thanx,
Rick

oufly2

I just painted a mini katona with rustoleum for plastic that I got at home depot. It goes on heavier than the Tamiya paint and takes longer to try, but it really seems to bond right to the foam and doesn't in any way come off when removing masking tape.

superjlulian38

When You Say EPS Do You mean EPP foam or some other new kind of foam

thojo

To smooth the foam, get the light weight spackle, mix 50/500 with water and brush it on the foam. Let dry and lightly sand. The spackle will fill the foam and give you a smooth surface...

Woody 51

I repainted my GWS A-10. Used Tamiya Acrylic from a spray can. No problems.
However, I did once use their Acrylic"Clear" to overspray and seal, the decals on my Alfa FW-190. The decals did not like the stuff and bubbled. However once dry, the bubbles disappeared. I suspect it was something in the propellant .

stevepollard

Here is one painted with H2O and Short Cuts.

Steve

GWR

My Feedback: (31)

Tamiya spray cans

Thermalrunner

Hi all-

Please hang in there with me, this is the first plane for me, and I'm not sure where to start. (been flying heli's)
First, all the information in this forum is great! I have a problem that I hope you all can help with.
I bought a PBY Catalina water plane, foam, that is already painted. It is blue and yellow. I would like to paint it white and red. I haven't received it yet, so I don't know if the foam needs sanding and filler as you mention. And it is as I mentioned, pre-painted.
What kind of paint should I use for a "water plane?" And should I do a primer coat first, and then my colors, after of course sanding and filler as mentioned? Or just paint over it? Please I'm new to water planes and painting, but I have the time and will find it enjoyable, so a step-by-step on what to do would be MUCH appreciated.
Thank you in advance and I am looking forward to being a part of these RC Forums.

Dean

longbikez

Thermalrunner, I would wash on some light coats of water based polyurethane varnish. After that is dry you can use just about any rattle can you wish to color up.
Otherwise I have a question of my own re: previously unpainted foam:
Has anyone worked with DYES? Seems like a light weight intense color solution to me. There are many types available either water based or alcohol. I have no experience with this but it sounds good. Anyone?

Glacier Girl

My Feedback: (4)

A dye might work, but you also may end up with a mess. The dye will drop into the crevasses and become much darker then the surrounding high spots.

Ok a few things. EPP is the hardest foam to get anything to stick too. And believe me, I've tried everything. Heck the recommended cleaning agent for EPP foam is acetone.
Put a drop on a GWS bird and it will melt right through it, on a Stryker, which is EPP, it won't even leave a mark.

Be careful sanding foam, if you sand too much in one spot it will heat up the foam and cause it to swell, and you're right back where you started.


Lastly, something I didn't see mentioned was glassing foam. Several variants of doing it. Lightweight fiberglass cloth and resin for strength, but it's heavy. Lighter is same cloth, but use water based polyurethane instead. Fairly strong. If you are going for smooth only, and really no additional strength, plain old newspaper and the poly.

Wanna see what it looks like? Check out my Eflite Super Airliner. Yep that's foam. And nothing more then newspaper and Christmas wrapping paper used with poly. Regular Rustoleum rattle can paint. Check out the reflections in the black paint to see how smooth it is.

IfIHadWings

GWR - I noticed the main and tail wheels on your Formosa. I'm building one now and have not intention of installing the GWS wheels, but I might install the ones you used...they look much better. Any weight concerns?

John Sohm

My Feedback: (9)

EPS = Expanded Polystyrene, the regular old beaded foam that's used for foam wing cores that get sheeted with balsa for us builders
EPP = Expanded Polypropylene
EPO = Expanded Polyolefin

tim allen

Ok , so i have a question; how are you guys sticking your tissue paper to the foam ? I have tried minwax first then tissue over it while the minwax is wet and tissue is dry and i keep getting wrinkles! They do sand out (kind of) but not without re-coating , sanding , and re-coating a LOT ! LOL