Introduction: Foam Sandblasted Sign

Picture of Foam Sandblasted Sign

This instructable will show you how to make a small sandblasted looking sign from simple and easily obtainable materials.

Step 1: The Materials and Tools

Picture of The Materials and Tools

Styrofoam: any type will do, beaded white (thats what I'm using here), or the pink, blue or grey extruded type of polystyrene. urethane foam will not work for this project. The colored foam is usually sold under the name foamular and is found at most building supply yards as foundation insulation, they also carry the white beaded foam and you can find it in some craft stores also.

Stencil material: I'm using sign vinyl that I cut on my Summa plotter using Coreldraw, but, you can use contact shelf paper handcut with an exacto knife. or even cutout stencils using chipboard or other materials, be creative.

Sandblast: For this project you could use a sandblaster (very quickly) but because of the polystyrene we are going to use spray paint any brand will do as long as it's not water based, solvents in a spray can will also do, experiment.

Step 2: Sandblasting With Paint

Picture of Sandblasting With Paint

Once you have applied your stencil it's time to "blast". start lightly spaying the foam and be careful of under cutting (bold designs work better as you will see), the paint or solvents will start melting away the styrofoam. Be sure to evenly coat the panel and keep in mind the chemical reaction will keep working after you stop spraying

Step 3: So Simple a Kid Can Do It

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My son Ian wanted to do one so we cut a small block of foam and put a dragon stencil on it, taped off the edges with packing tape and he went at it.

Step 4: Finishing Up

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when the paint is dry, remove the stencil and tape and coat out with a water based coat of paint or primer then finish paint using the colors of your choice. You can safely use spray paint after priming at least two times with a water based paint to protect the foam, but any little pinhole in the primer coat will let solvents get to the foam so at least two coats need to be applied. I use acrylic latex house paints and/or artist acrylic colors to paint my foam signs.

Step 5: Fixing Mistakes

Picture of Fixing Mistakes

The Fedosky sign had an issue with the stencil lines being too fine, so I cut the parts from chipboard (leftover from my bookmaking) with my scrollsaw and coated them a couple of times with krylon paint to make them more durable, if the sign were going out in the weather I would use acrylic, pvc, or wood. I will then glue them to the sign after painting. You could also add other decorative elements as appropriate the style of sign

Step 6: Finished Signs

Picture of Finished Signs

I'll add the signs later

Finally uploaded the finished pics (1-12-09)


Chirpy Chirp (author)2015-09-19

I just found this yesterday and have had it up showing the family, this is an awesome idea for house number plates using lost foam casting, expecially lost foam casting with brass.

How deep does the foam get eaten in from the paint and what paint would you reccomend for getting fairly decent engravings?

peterman921 (author)Chirpy Chirp2015-09-20

it wont go far without eating under the stencil so beefy graphics are best. as it goes down it spreads out, keep this in mind

dont get too heavy too fast let the solvents work

I use Krylon but most any aerosol should work. look for xylene and petroleum products in the list of chemicals

just lay out some paper or cardboard on some foam and experiment

in fact if your going to make many address plates make the numbers out of cardboard to keep from re-cutting each time you make a plate

Chirpy Chirp (author)peterman9212015-09-21

thanks for replying and I understand about it eating under the stencil, the plates would be just one offs so just bury the foam and everything in the sand to cast it. Thanks again for the great instructable.

reinlar (author)2010-06-07

What reasonably cheap (and readily available) liquid type finish could you dip or spray onto your sign, to make it HARD and more durable and long-lasting than painted foam. I guess clear fiber glass resin & hardener would eat the foam wouldn't it???

I used to know a commercial sign maker who cut letters out of pink construction insulation type foam (from Home Depot) and he dipped them into something which hard-coated them for durability against the outdoor elements, but can't remember what it was. It would be perfect for making this sign technique durable enough to use outdoors. Anybody know what he used.????

peterman921 (author)reinlar2010-06-07

I doubt it was cheap. you can use epoxy resins without melting the foam, polyester resins are too hot. there are two part urethane coatings available, try set design websites, foam coatings, hardcoat, props, etc.

reinlar (author)peterman9212010-06-07

Thanks for the links, but I think the stuff I'm talking about was (1) component, non-toxic, 24 hr cure, and cleaned up with water. The guy didn't even wear gloves when he dipped his signage into it. I'll track him down in the next few weeks and post his links. He may have even had a formula for self-mixing the stuff. It looked like white latex paint but thicker, dry to touch in an hour and in 5 days it was pretty dogone hard. Felt like plastic, but flexed enough so it didn't crack if you hit it. I know it was only guaranteed to remain intact for 3 years. He got repeat business, because his signs were good, and cheap. I also remember he attached plain roofing nails to the back of his signs and pushed them into holes with blue anchor plugs for mounting. Very simple, cheap and quick. His signs never got damaged, except during hurricanes of course. He made a ton of money traveling around Florida in April-August.

peterman921 (author)reinlar2011-02-09

it occurred to me a few weeks ago it might be snow seal roof coating. it's white and I believe waterbased, I'll have to go get some for my roof anyway, I'll try it out

adel_sebaey1 (author)2010-06-15

v. good man; any other works pics.

peterman921 (author)adel_sebaey12010-06-15

yeah, check out my website and my facebook!/pages/Grants-Pass-OR/JP-Graphics-Artistry-and-Design/230729986988

Mig Welder (author)2010-03-23

cool! that's tiny drill press!

penumbra_ (author)2009-10-04

So you can paint over the initial spray paint coat with acrylic paint? Not acrylic primer? I wasn't sure how well acrylic paint would adhere to the enamel, but if you could skip a primer coat that would be nice.

uguy (author)2009-01-09

You could use some of the 2 part Faux Stone paint and make it really look like sand blasted stone. We did this at a vinyl sign shop I worked at. Looks Great, Great ible, thanks for sharing.

scavanger (author)2009-01-08

Great idea I always knew paint did this to foam, but never thought to use it to my advantage!

peterman921 (author)2009-01-07

And some more at my flickr photostream the coolcat job was just done 2 months ago.

peterman921 (author)2009-01-07

more of my work here some is foamular and some is urethane foam

Weissensteinburg (author)2009-01-07

Cool! I've never thought that this property of Styrofoam could be anything but a nuisance.

PS118 (author)2009-01-07

I'm with the others. Very cool idea melting the foam on purpose to make designs. I bet you could use this to create molds for concrete or other materials. Also, wonder how far a person could take this. CNC / Reverse stereo lith machine, anybody?

peterman921 (author)PS1182009-01-07

well there is also lost foam casting that I have done using my cnc mill to make the parts in foam bury them in dry sand with a foam runner coming up to the surface and pore in your molten aluminum, let cool and out comes your aluminum part ready for finishing. I'll make my web page into an instructable

jeff-o (author)2009-01-07

Wow, that looks really good! I like how you've turned a nuisance (melting foam) into something useful.

webman3802 (author)2009-01-07

This also works great for making tombstones for Halloween. You can apply a stencil that will only etch the "RIP" or other letting, and use this technique once or twice (allowing to "dry" between sprays) to carve out the letters. Then, remove the stencil and apply a light dusting of spray to the entire tombstone to give it an overall grainy texture. For added details, you can chip out cracks and "crumbles" with the tip of a knife before or after spraying (this probably wouldn't work as well with the beaded white foam). When painting, after the main color, a dark wash of thinned-out black or brown will show off the details nicely.

webman3802 (author)2009-01-07

I accidentally discovered this technique while making a blue foam King Tut mask for a sarcophagus I made for Halloween one year. I knew it would melt the foam, so I used one coat of water-based latex (brush-on) primer. Not enough, obviously, but instead of pitting the the foam, only a little of the solvents leaked through the primer, giving it a wavy, dented look in some areas. It worked well for aging the mask, even though I wasn't expecting the effect. You can also use a hobby knife to slice shallow cuts into the foam before spraying. More of the solvents will leech into the cuts than the surrounding area, and you will end up with slight grooves in the etched surface.

craig3 (author)2009-01-07

if you use blue spray paint will the melted foam turn blue?

peterman921 (author)craig32009-01-07

yes, you can use any color you like but you still have to prime and paint especially if its going outdoors, so it doesn't matter what color you use to blast with.

rimar2000 (author)2009-01-07

Very smart, good work.

courtney (author)2009-01-07

nice! I used a similar technique to faux finish some Styrofoam volcanic rocks for an art project, but never thought of making a sign that way. cool!

gmjhowe (author)2009-01-07

Nice work, alot simpler than i first thought!

ChrysN (author)2009-01-06

That looks really nice!

CameronSS (author)2009-01-06

Very nice! It looks great!

foobear (author)2009-01-06

interesting idea!

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