Make Foam Look Like Carved Granite!

I like to make signs, so when I saw an excellent instructable on making foam "sandblasted" signs, my ears perked up! I make them too, but have what I think is a simpler method. Check it out.

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Step 1: Cut out your letters

In this step, you make the letters to be used for the resist. The letters prevent the foam from dissolving, much the same as in sandblasting. I use my word processing program to print out the message I want to use. The letters are easily cut out with scissors as seen in the picture.

foobear says: Apr 13, 2013. 8:10 AM

Does this technique work on craft foam sheets? (I just tried it with no luck.... maybe I should try using straight acetone). Thanks!

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Creativeman (author) in reply to foobearApr 13, 2013. 9:37 AM

No, only use eps foam or styrofoam!

ClayOgre says: Jan 19, 2009. 7:15 AM

Do you realize what you've got here? I have seen stuff on the net where people have gone to great lengths to build CNC milling machines to cut foam.

Why? so they can do lost foam casting with metal. I can see where you could perhaps use this technique to make the mold.

Have you tried it with other types of foam? I.e. like the pink or blue tight cell foam used for insulation?

What if you just used a squirt bottle to mist the foam with straight acetone?

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Creativeman (author) in reply to ClayOgreJan 20, 2009. 6:29 AM

Hey Clay: My experiments show that this method does not have enough control for making molds...maybe you can do better...I tried the blue and it seems pretty much the same. So either or. Acetone would be too strong, you could dilute it, but why bother? Thanks. Cman

stringstretcher in reply to CreativemanOct 5, 2011. 12:38 PM

pieces that are cast are usually over dimensioned and worked up later using milling machines and the like. This may well work for certain applications! Cool!

ClayOgre in reply to CreativemanJan 20, 2009. 10:37 AM

hmmm, enough control. Well, then if one were to use it for metal casting, then each object cast would be one of a kind, which would have it's own possibilities.

maruawe in reply to ClayOgreJan 19, 2009. 8:45 AM

You can use acetone,but it melts foam really fast , I use it to melt foam to make led rocks( button battery and led taped together ,then covered in the melted foam,and rolled into shape desired). Don't know what to mix acetone with to dilute the mixture (a little help on that one if you please) but that would help.

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Creativeman (author) in reply to ClayOgreJan 19, 2009. 7:53 AM

Thanks for the info...I have seen other processes of course, but what I do is try to duplicate those processes with what I have on hand. Isn't that what art is? Some of those machines are 50-100K! Mymehods are free (almost) I've heard of lost wax molding....but I like "Lost foam"...cool. I'm going to try the blue...should be the same, but may be more controlable...we'll see. Acetone? that might work as well...I will ponder that, don't have any acetone right now. Thanks again, let me know what you think. Cman

ClayOgre in reply to CreativemanJan 19, 2009. 5:08 PM

If you look on youtube, there are vids of people doing lost foam. In fact, one of them is a guy who has several vids of taking one of those foam skulls they sell at Halloween time and using it to cast a funky aluminum trailer hitch decoration for a pickup truck.

Koevoet92 says: Aug 24, 2010. 12:46 PM

I know I'm a bit out of date here but I simply wanted to thank Creativeman for this great idea, my second Instructable I've started (1st, 3'd, 4'th still in progress :S ) that is now officially finished.Wife and I have a little cake shop and I used this idea to make a 1m x 1m board with all the cake fillings we offer.
Again, thank you Mr. Creativeman

P.S. I wish your work shop was mine!

Hernando in reply to Koevoet92Jan 20, 2011. 7:00 AM

I love your sign!
If you are going to put it outside, what coating materials will you use?

Koevoet92 in reply to HernandoJan 20, 2011. 2:15 PM

Thx for the compliment! but no, its inside our shop.

I have though since discovered a material -here they call it "alto impacto" (if I got it right through the wiki in English its called HIPS or High Impact Polystyrene) - which should be able to do the job outside in not to high temp regions. Here you get them from 0,5mm onwards which cuts very easily and is 1/5 the price of Plexiglas...

somebody demon says: Jan 2, 2010. 6:49 AM

great i will try it thanks a lot

SarahBellum says: Dec 31, 2009. 7:54 PM

Thanks for the great ideas! Using my standard printer, I printed my text from a word document on to adhesive shelf liner (Con-tact Paper). First I cut a piece of the paper to standard 8 1/2 by 11. So that the letters maintained accurate spacing I cut out everything using scissors and an exacto, but left a tiny line connecting each letter at the bottom. I easily clipped that off after it was layed out on the foam.

Since I used acetone rather than spraypaint, the paper's color was removed, but it still removed very easily, and created clear letters.

Creaturiste says: May 31, 2009. 4:58 PM

Hey, this is very cool! A combination of concepts I knew separately, brought together by you, for an efficient effect! Thanks! Now, how do we protect our foam sign from wear and tear? Foam is easy to bump and chip off. I'm a paper mache specialist, so I know two layers of paper towels and diluted glue will hold on quite well, but that would hage the texture quite a bit. Any good idea with common materials? I know about Rosco Foamcoat, and even Sculpt or Coat, but I'd prefer a finish that isn't palstic-like...

robsrad in reply to CreaturisteDec 2, 2009. 8:36 AM

i saw this instructable and automatically thought of creativemans other instructable about making letters in concrete. So to make it more durable i was thinking of putting the letters on backwards then useing that as a form to pour colored concrete over. I will definitly be trying this out as a christmas present. Nice job creativeman.

kcli says: Nov 13, 2009. 4:23 AM

Glad to see this in the Halloween entries...good luck in the contest!

piaferre says: Aug 16, 2009. 4:19 PM

this is SO usefull!! so simple and great results, thanks for sharing =)

Quiff says: Apr 14, 2009. 6:59 AM

Very nice. Is there an easy method of removal of the masking so the underneath (masked) part stays smooth? Have you tried 77 spray glue on the masking rather than white glue and if so, did it remove cleanly?

jontjack in reply to QuiffJul 9, 2009. 9:42 AM

77 spray glue will desolve the foam as well, that has been my experience. I bought 'special foam glue' once and it was just white glue. White glue worked very well for a project of mine that stacked 10 layers of foam to form a block.

lawdog323 says: Apr 21, 2009. 9:47 AM

what is resist paper Creativeman?? I love this idea. Very simple yet an awesome outcome..

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Creativeman (author) in reply to lawdog323Apr 21, 2009. 1:07 PM

Thanks LD323: Resist is a material used in sandblasting to prevent the process from removing material under the design....I use it loosely to describe the paper I use (which is simply cardstock) to do the same thing with the spray paint. Cman

natethegreat88 says: Mar 25, 2009. 2:01 AM

I remember when I was like 7years old and was in cub scouts and we had to make a rocket that would travel along a clothesline kind of like a pinewood derby. the block i got was foam and when i was done sanding I spray painted it with spray paint that had cetone in it and it ate away my whole ship and so it looked like a black crumpled up peice of trash.

LindaLW666 in reply to natethegreat88Apr 4, 2009. 8:10 AM

...and you still worry about it. now that you're 17. Look, I'll buy you another, okay? Love, LW

neubaten in reply to natethegreat88Mar 25, 2009. 8:02 AM

that made me feel all sad and wistful, like a scene from gummo or something. le sigh....

Lori Ell says: Mar 11, 2009. 3:16 AM

How clever. I love to see how creative and clever people are. Really beautiful. People who do skits and plays will love this. The stone discs are awesome. Thanks for sharing!!

MrPumpernickel says: Jan 24, 2009. 7:16 PM

1. Ensure for good ventilation, 2. Wear a mask. The fumes that comes from chemically burning foam is bloody nasty and may over time cause respiratory problems.

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Creativeman (author) in reply to MrPumpernickelJan 25, 2009. 6:37 AM

My Muse always told me: "If you don't have anything constructive to say...." Cman.

MrPumpernickel in reply to CreativemanJan 25, 2009. 5:38 PM

My muse always told me "That's a worthless way to look at things, if you can't take and give criticism you might as well stay at home under the sheets and never do anything with your life." But that's a sideline and really has nothing to do with this. Either way, I don't see how what I wrote is not "constructive", it's basic safety tips which I hope anyone that tries what you wrote about takes seriously. I like the instructable, just wish you'd make an addendum so people understand to do this at the very least where it's well ventilated. I'm sure you don't want to cause anyone to do undue harm to themselves, right? We had a guy here at university who did something similar in the workshop a couple of months ago, he ended up passing out and spent three days in the poisoning unit at the hospital, hence it deserves to be taken seriously.

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Creativeman (author) in reply to MrPumpernickelJan 25, 2009. 9:48 PM

Safety is always a concern, is basic common sense. I think your issue is like telling people to be aware that the wheels on a car will roll if the car is put in gear. May be dangerous to your health. Hence my Muse's input! Have a nice day. Cman

MrPumpernickel in reply to CreativemanJan 26, 2009. 12:16 AM

I don't know, if sense was in any way common we wouldn't have warning labels on chainsaws that read "Don't attempt to stop chain with hands" and so forth.

amywho in reply to MrPumpernickelFeb 26, 2009. 12:37 PM

MrPumpernickel. Thank you for pointing out the obvious. I too hold this thing we call 'common sense,' but not everyone has it. The older I get the more I've learned that the greater population aren't really born with common sense. If everyone had it, there would be no such thing as the Darwin Awards. Unsure of the reference? Google it. And the children, creativeman. Thing about the children....just because they're not SUPPOSED to try something like this alone, doesn't mean they wont....

dianakob2 in reply to amywhoMar 11, 2009. 3:11 AM

Thanks for the heads up. I have to agree...if people used common sense, they wouldn't have need to put "contents are hot" on the McDonald's coffee cups to let people know that if you put it between your legs and it spill...you're probably going to get burnt! BTW, the Darwin Awards are a riot!

cloudhidden says: Feb 6, 2009. 8:04 AM

I really liked the idea. How does this hold up for exterior use?

hammer9876 says: Jan 22, 2009. 3:03 PM

Excellent. A lot easier than sitting around carving "R. I. P." in a block of foam. The eating away part reminds me of the neighborhood kid that just wanted a little bit of gasoline for use in our summer project. He wasn't too bright, however, because he used the garden hose and sucked some gas out of tank of his car. (Kids, don't try this at home!) When the gas started coming out, he directed the liquid to a Styrofoam cup - which instantly dissolved. Made quite an impression on me. He went on to major in Chemistry in college. Better life through chemistry.

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Creativeman (author) in reply to hammer9876Jan 23, 2009. 6:13 AM

Thanks. Cman

mogimbu says: Jan 22, 2009. 11:31 AM

I made Mayan Stone Disk prop with a simalia rmethod a few years ago. The insulation foam I used has a layer of plastic cling on it. I cut out the design, then pulled off the area to be etched. I was able to use an inexpensive plant sprayer to apply acetone to the piece. I like your method as you can skip one step of painting. Well done.