Painting Foam Board

[jhitesma]

Going to resurrect this thread to share something interesting I just learned this weekend.

Food Coloring. The liquid kind. If you have an airbrush try it!

Jaxx posted this great airbrush basics video earlier this week: http://forum.flitetest.com/showthre...you-re-interested-in-airbrushing&goto=newpost

I was so impressed by it I did a search on the owner of Badger to try and see if there was more from him out there. My first "airbrush" was a badger 250 I got probably about 30 years ago...but it's more of a mini spray gun than a real airbrush. I still have it but it's been sitting uncleaned and clogged for about 28 years because it wasn't much better than rattle cans for accuracy and control ability. To be honest it kind of turned me off on airbrushes in general and badger in particular. Though after doing more research this week I've just added Badger 105 Patriot to my Christmas list. (I currently have a Pasche VL but I'd like to try a gravity feed and there are a couple of things about Badgers design that are really appealing to me.)

Anyway, the point is that search turned up this site: https://sites.google.com/site/donsairbrushtips/home which has a bunch of great airbrush information (though some of it contradicts what the president of Badger says in the video Jaxx posted - even though the author is a huge Badger fan.)

What I found interesting about that site is that the owner uses ink and/or food coloring to spray on paper towels for his tests comparing brushes.

I have some expired food coloring sitting in my cabinet so I figured I'd give it a try and see how it does on foam board.

Turns out it does great! Spraying "normally" (meaning multiple light coats) with straight unthinned food coloring gave me wonderfully vibrant colors that blended well (like transparent paint) and were super easy to spray and cleanup since it's all water based. Even doing really heavy coats trying to see if it would warp the foam I only got minimal warping of the foamboard. Much less warping than windex thinned acrylic gave me.

I haven't tried it on minwaxed board yet, will dig up a few scraps to try it on tonight. And I haven't tried minwaxing over it yet (was going to today but it's crazy windy and dusty out and I can't use minwax in the house so that will have to wait.)

Anyway - if you've got an airbrush and food coloring on hand dig up some foam scraps and give it a try. I'd love to hear if it works well for others as well. It's cheap, gives nice vibrant primary colors, cleans easily, and despite being water based if sprayed gently doesn't seem to warp DTFB.

 

[Jaxx]

Jhitesma,
How does the food color hold up after it has been applied and dried? Does it smudge if it gets wet? I'm really getting into this airbrushing thing. I'm about to go look for some food color (I know we have some around here somewhere). Did it require a lot of thinning? Thanks for the great information.

 

[jhitesma]

Not sure yet how well it will hold up. I'm sure it won't hold up to moisture...but then again neither will untreated DTFB. That's why I really wanted to try coating it with minwax to see if that would protect it. I suspect it would wash off if sprayed on pre-minwaxed DTFB - I'll be painting a piece of pre minwaxed board later tonight to find out.

I just did a little test on the piece of untreated board we painted last night. I wet my finger and dragged across some of the painted sections. The color did run a little but not nearly as much as I had expected.

Here's the test piece my daughter and I did playing around last night:



If you look at the big green splotch above the face you can see where I dragged my wet finger through it.

Mixing the colors straight did not work well. But since they're translucent you can layer them on top of each other and they blend well. The brown bits are where I tried mixing blue and red to make purple...they didn't blend well when mixed before spraying.

It didn't require any thinning since it's as thin as water already. Though I suspect it could be thinned out a bit to modify the color - I'd just be a bit worried about warping the foam then since you'd be spraying mostly water.

I also have some gel food colors and may experiment with thinning them with water and spraying them since they're available in a much wider range of colors than the liquid food coloring.

It's not a perfect media - but for airbrush practice and painting a cheap plane that you don't expect to last a long time it sure seems to have promise.

 

[jhitesma]

One more note...doing a search to see if anyone else has tried this I found a couple of "Things from dollar tree you can use to entertain your kids" lists that mentioned DT carries food coloring as well. I'll have to check for that next time I go.

If they only carried servos, piano wire and RX's....so close to building an all DT plane

 

[Jaxx]

One more note...doing a search to see if anyone else has tried this I found a couple of "Things from dollar tree you can use to entertain your kids" lists that mentioned DT carries food coloring as well. I'll have to check for that next time I go.

If they only carried servos, piano wire and RX's....so close to building an all DT plane

Thanks again for the information. I will have to swing by the DT and check this out.

 

[jhitesma]

Just did a test with food coloring on pre-minwaxed DTFB. As I suspected that does NOT work. It just beads up and blows off in the air from the airbrush. If you get really far away it kind of almost sort of works since most of the water evaporates before it hits...but it never really sets and just wipes right off. Plus the colors look horrible on top of minwax.

The wind has calmed down but it's too dark and cold for me to go outside and try minwax over food coloring tonight. Will try and do that experiment in the next few days.

 

[Jaxx]

Just did a test with food coloring on pre-minwaxed DTFB. As I suspected that does NOT work. It just beads up and blows off in the air from the airbrush. If you get really far away it kind of almost sort of works since most of the water evaporates before it hits...but it never really sets and just wipes right off. Plus the colors look horrible on top of minwax.

The wind has calmed down but it's too dark and cold for me to go outside and try minwax over food coloring tonight. Will try and do that experiment in the next few days.

Cool. Looking forward to hearing the results.

 

[jhitesma]

Was able to do a quick test tonight and confirmed that oil based minwax goes over the top of food color with no problems. Just need to let it dry overnight before I can test how it affects the food colorings permanence. I assume it will seal it in...but we'll see how it works in practice!

 

[Jaxx]

Cool. Let us know how it affects the color.

 

[jhitesma]

The minwax didn't really noticeably affect the color at all. It did give the exposed white areas just a slight yellow tint as it always does - but other than a slight gloss it didn't affect the look of the food coloring at all.

And as I suspected it did seal the food coloring in and water no longer affects it.

 

[viggen]

do you have any pic's?

what is minwax?we dont have that in the uk.

any idea's what else i could use?

 

[gabrielete]

There's people that says alcohol destroys foam, but I paint using 50% Tamiya-Alcohol with airbrush directly to the foam (no minwax) and dries instantly. Also gives a matt texture very nice for military schemes.

 

[insomaniac45]

do you have any pic's?

what is minwax?we dont have that in the uk.

any idea's what else i could use?

Polyurethane based wood varnish.

but if your using WestFoam (as you said UK) then the west foam is already slightly waterproof as it is glossed paper. it will take pretty much any paint, as the paper protects the foam from the harmful propellant from rattle cans.

If you are using rattle cans, spray at least 8" away. that way it gives the propellant time to disperse.


But go to B&Q or homebase, or wickes, and look at their wood varnish. you should be able to find a decent polyurethane based varnish

 

[viggen]

Polyurethane based wood varnish.

but if your using WestFoam (as you said UK) then the west foam is already slightly waterproof as it is glossed paper. it will take pretty much any paint, as the paper protects the foam from the harmful propellant from rattle cans.

If you are using rattle cans, spray at least 8" away. that way it gives the propellant time to disperse.


But go to B&Q or homebase, or wickes, and look at their wood varnish. you should be able to find a decent polyurethane based varnish

thanks for your reply.im using 5mm formboard from ebay.i will have a look to see how water proof it is
im going to airbrush my ft spitfire and slinger using food colouring...does anyone know if it will also stick to the poster board or (plasty card in the uk.)

do i need to add varnish over the top of the paint?
ive very new to all things rc
thanks

 

[insomaniac45]

PVA glue mix

there is a product called foam armor, it is basically pva glue. if you add pva to your paint mix, it will add a small amount of weight, but it will also seal the paint, and allow it to stick to shiny surfaces better.

 

[viggen]

hi please can you help.i airbrushed for the first time and painted my plane the black.came out amazingly.but my green is very blotchy..any one know why.and how i can stop it happening...i used blue and yellow mixed together and then 50% paint and 50% wendex...could it be the paint is to thin?thanks

 

[pistolpete1982]

Posted in another sub forum also... But when using minwax do you guys also apply to the poster board canopy? Or just the foam board?

 

[Art Lane]

I have a question regarding the MinWax..... Can this stuff be thinned for Air Brush use?? I'd sooner airbrush the minwax on than brush...
(or have I missed this answer somewhere in this forum????????????
Art Lane

 

[PeterGregory]

Mineral spirits or paint thinner, according to the minwax website
I did spray my DTFB with thinned minwax. Checking now I see I bought a gallon of Laquer Thinner from Home Depot for more spraying yet to come. The DTFB I did spray is very yellowed now. Also, there was a disclaimer added to the FT "How to paint DTFB" that what they showed in the video was not recommended - spraying the entire sheet first.

 

[RAM]

The only thing you might watch for when thinning is the solvent lifting the paper off.