Painting Foam Core Board? March 03: GREAT PAINT FOUND!

Alex,
I used some foam core board for city streets, spent hours cutting it to fit a boulevard double track crossing. Painted it with Polly scale acrylic concrete paint. Looked fantastic. Went to bed, woke up, came down to check on it and it looked like a pile of potato chips!
Now I use Masonite pressed hard board, great for emulating concrete.
Looking back I should have sprayed the foam board with a primer or sealer.

I have painted the foam core board with latex and it did not damage the surface, but slightly warped the board. Fortunately, it was for a building base and adjacent parking lot, so I was able to glue it down and make it flat.

 

I just learned about a spray paint - ColorTool by Design Master - which I believe is intended for delicate items (flowers) and it is supposed to work well on the foam core board. I wonder if anyone in the forum has used it?

 

Thx!

 

Alex

Alex

I was reading a similar thread yesterday. Seems like a lot of guys use the Masonite. There was one who used 1/4 inch for sidewalks and 1/8 inch for the road. It is suppose to be equivalent to a 6 inch curb from the road to the sidewalk.

Larry

Alex...as you already know, I use foam core for a lot of my projects and generally don't have a problem with it.  The granary I built for you used foam core.  I painted it with oil based spray....not water based acrylic.  Water based even on the edges, if applied too thickly, will expand the cells in the paper coating and then wrinkle.

 

I cover the edges, when needed, with very thin painters tape and then paint over it.  Many times this ends up simulating the thicker reinforced concrete corners of certain concrete buildings.  Take a look at the granary and you will see what I did.

 

There is a tool that will cut a 45 degree angle as you cut foam core which would allow you to joint two wall with no edge showing.  As far as using foamcore for roof sections, you can always cut it to fit within the boundary of the walls on top of the structure rather than over hanging....this may help with eliminating having to paint the edges of the foam....

 

Alan

Alex, if you still want to use the foam core, try painting both sides with the latex paint. The back side doesn't need to be perfect, but when you do that it doesn't "know" which way to warp and should stay pretty flat. A trick I learned long ago.

Thanks for the suggestions.

 

However, as I had said, the building is finished, so foam board it is. The building is 16" wide x 24" deep x 28" high. I have access to the inside to paint it, but it would not be easy. Also, there are 75 window cutouts, and that means 300 edges.

 

I'll report back . . .

 

Thx.

 

Alex

The cutter is made by x-acto. if you go to purchase one from a craft store you will get sticker shock. They were $19.95 at Michaels. When Ted pointed them out to me he provided a link to Walmart.com. They were about $4.00. In fact I bought 5 of them for the $20.00 that Michaels wanted for 1 and the shipping was very reasonable. (Don't ask me why I ordered 5 of them! I have no idea.  

Alex, though slightly off subject in application, but years ago when I used fanfold insulation and pink thick sheets for wings or cutting wing cores on my park flyers, the paint I used was acrylic based tamiya spray and bottles...it seemed anything that was solvent based, no matter how thinly applied, would eat the foam to some extent. That foam board your using should have the cardboard laminate on it and that will soak up paint and swell...light coats and letting them dry completely before the next application{light coats all the way thru to end}, and using foam safe paint, should wind up with a nice building.

I was thinking of trying foam board for buildings...they won't crash on too windy a day...guess I could never find too many calm days to fly!   

I use a rabbet joint on one of the two pieces to be joined. I remove enough foam and leave the outside lamination. Didn't have a 45 cutter. Leaves a similar edge as the 45. Thanks, Strogey, I'll be ordering a couple of those.

Thanks for the painting tips, everyone. Someone's always tried it before

I am very happy to report that the Design Master paints work GREAT!

 

Michael's had some, but not the colors I wanted, so I ordered my paints from Direct Floral, whose prices were about $2 less than Michael's.

 

The Design Master ColorTool paints are incredible for this application. They absolutely do not harm the foam core board. I sprayed it directly on the edge to test, and not any sign of melting or warping. Painted just one side of the board, and absolutely no warping at all.

 

For my project I used the Design Master Primer No. 645 (Grey) and after just one coat, finished it off with the Design Master ColorTEX No. 862 (Quarry).

 

WOW! The ColorTEX, which is a textured finish, covers incredibly well. Just one quick pass (spray) and the surface is thoroughly covered. Quick spray the inside corners, and the ColorTEX builds up a nice fillet.

 

I will be posting pictures of the finished project soon, but in the meantime I have attached a close-up picture that shows the paint finish.

 

I couldn't be happier with a product and the results!

 

Design Master: http://www.dmcolor.com/

 

Direct Floral: http://www.directfloral.com/se...chterm=design+master

 

Alex

 

(Click for full-size) 

Good info, Alex.  I like that finish.  Thanks.

Dennis,

 

The finish does look great - just a bit of roughness. However, when it is sprayed and for about a half hour or so afterwards, the finish is really rough. The first time I tried it, on a test piece of board, I did not think it was going to work because it was so rough. But as it dried, the 'bumps' shrunk until the finish was almost flat; just right for our scale models.

 

Thx!

 

Alex

Hi Alex,

 

Do you think that the finish seals the fomecore enough to paint over it with other colored acrylic craft paints?

Mark,

 

I really do not know, but will test a sample Wednesday and let you know.

 

Alex

That gave a really nice finish to the foamcore Alex

Mark, et al -

 

I painted three 2” x 6” pieces of white foam core board (from Michael’s) with three different paints and a clear finish, all one coat, as follows:

 

Piece 1

1st – Design Master Primer No. 645

Effect: Barely noticeable on the foam core, which may have receded 0.010”

2nd – Rust-Oleum Painter’s Touch Ultra Cover 2X Satin Oregano No. 249069

Effect: Caused the foam core to recede slightly more; about 0.020”

 

Piece 2

1st – Design Master Primer No. 645

Effect: Barely noticeable on the foam core, which may have receded 0.010”

2nd – Design Master ColorTEX (textured) No. 862

Effect: No further than the barely noticeable caused initially by the Primer.

3rd - Rust-Oleum Painter’s Touch Ultra Cover 2X Satin Oregano No. 249069

Effect: No further than noticed before.

 

Piece 3

Rust-Oleum Painter’s Touch Ultra Cover 2X Satin Oregano No. 249069

Effect: Caused the foam core to recede about 0.030”, just barely more than when sprayed over the Design Master Primer as in Piece 1.

 

Then I sprayed one half of each of all three pieces with Rust-Oleum Painter’s Touch Ultra Cover 2X Matte Clear No. 249087.

Effect: Very noticeable on the foam cores of Piece 1 and Piece 3 and caused their cores to recede about 0.110”. However, the effect of the Clear spray was barely noticeable on Piece 2.

 

In conclusion.

• None of the sprays cause any warping of the foam core board.

• The Design Master Primer and TEX paint had none to barely noticeable effect on the foam core.

• The Rust-Oleum Painter’s Touch paint spray had little effect on the foam core.

• The Rust-Oleum Painter’s Touch Clear spray had very noticeable effect on the foam cores except on the board that had been sprayed with the Design Master TEX paint.

 

Any of the Design Master paints work well, and even when sprayed heavily and directly onto the board edge, causes minimal to no effect on the foam core.

 

The Rust-Oleum Painter’s Touch paint I used did not appear to be a problem as long as it is not sprayed too heavily directly at the edge of the board. It works well also when sprayed over the Design Master TEX paint as if a different color texture is desired than those offered by Design Master.

 

The Rust-Oleum Matte Clear spray noticeably affects the foam core unless the board has been sprayed first with the Design Master TEX paint.

 

I suspect that different paints, even if from the same manufacturer, may affect the foam cores differently. Bottom line - try them first, and don't spray the edges too heavily.

 

Alex

Just as a cautionary note, warping often doesn't happen instantaneously. Some paints take weeks, even months before the foamboard begins to warp. If it's not braced it could still happen over time.