Introduction: Make Foam Look Like Carved Granite!

Picture of 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.

Step 1: Cut Out Your Letters

Picture of 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.

Step 2: Glue Letters to Foam

Picture of Glue Letters to Foam

In this step, the letters are placed where you want them and glued in place. I use regular white glue in generous amounts to insure complete adherence. Don't overdo it though, or you will be waiting a long time for the glue to dry.

Step 3: Ready to Spray

Picture of Ready to Spray

Pick a spray paint that contains acetone, the key to dissolving the foam. This will be listed on the ingredients label as "Ketones". Test the paint to make sure it works.

Step 4: Spray Your Sign

Picture of Spray Your Sign

Start spraying as you would any project...not too thick, not too thin. The correct amount is determined by experimentation, but it's hard to over spray. If the paint pools, it will eat all the way through.

Step 5: Complete Your Sign

Picture of Complete Your Sign

After spraying as many times as you think necessary, sign is ready to finish. Choices include leaving the resist paper on and painting perhaps, or removing the paper for a more "chiseled" look. Take your pick. See samples for various results. The possibilities for making signs is endless: think tombstones, house numbers/plaques, garden markers,direction signs, and so on.


ClayOgre (author)2009-01-19

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?

maruawe (author)ClayOgre2009-01-19

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.

Tangski (author)maruawe2015-06-17

you can thin or reduce acetone with water. It is the only one that you can do that with! Read the label and for best results test your pieces. I found however, I would rather use a paint with very light spray to get results that I wanted in a sculpture, as you not only save time, but now you have a foundation already started. However, if you just want to melt and get the depth you want a bit at a time. When you are ready to paint be sure to use a water based paint or you will keep going deeper into the material! I use a latex primer/paint. Spray it on larger panels, or brush on with smaller pieces. Depends of course on the project. I also top coat some areas with a mat or semi gloss water based clear coat. That helps to make them stronger and more wear ability for kids. There is also a great product out there that you can also solid coat a sculpture to make it weather proof and last a very long is especially made for foam creations of all kinds. What is nice is that it is also very affordable too. I have done a soil room with larger sculpted Spring tails and other soil critters doing this method. Turned out just great for a nature display exhibit~!

have fun creating!


Creativeman (author)ClayOgre2009-01-20

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

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 (author)Creativeman2009-01-20

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.

Creativeman (author)ClayOgre2009-01-19

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" 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 (author)Creativeman2009-01-19

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.

beststriker (author)2014-12-16

Beautifull letters in granite, is possible to make it granite setts also?

Erchan (author)2014-02-08

Hi, this really great project. I wonder what kind of foamboard must use? Do you know the technical specifications of your foamboard used in this project?

There are EPS (EXPANDABLE POLYSTYRENE) and XPS (EXTRUDE POLYSTYRENE) at the marketplace. XPS is harder material than EPS includes some kind of chemicals. EPS is usually white color and softer material than XPS. Moreover, these products are produced in various densities of between 10kg/m3 - 30kg/m3. The higher the degree If density material is getting so hard. It also increases flexibility density decreases. Please tell me which one did you use, or which do you recommend?

And did you ever mean to use a different dissolving chemical? May be spraying only acetone or liquid gas etc.?

Thank u

vampysleuth (author)2013-06-01

Hi Cman, if I glue my resist letters to the foam, then want to remove them, how will they come off?

Creativeman (author)vampysleuth2013-06-01

They will just peel off. If there is any resistance, soak with water then remove.

foobear (author)2013-04-13

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

Creativeman (author)foobear2013-04-13

No, only use eps foam or styrofoam!

Koevoet92 (author)2010-08-24

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 (author)Koevoet922011-01-20

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

Koevoet92 (author)Hernando2011-01-20

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 (author)2010-01-02

great   i will try it   thanks a lot

SarahBellum (author)2009-12-31

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 (author)2009-05-31

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 (author)Creaturiste2009-12-02

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 (author)2009-11-13

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

piaferre (author)2009-08-16

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

Quiff (author)2009-04-14

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 (author)Quiff2009-07-09

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 (author)2009-04-21

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

Creativeman (author)lawdog3232009-04-21

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 (author)2009-03-25

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.

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

neubaten (author)natethegreat882009-03-25

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

Lori Ell (author)2009-03-11

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!!

Switch and Lever (author)2009-01-24

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.

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

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.

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

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 (author)Switch and Lever2009-02-26

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 (author)amywho2009-03-11

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're probably going to get burnt! BTW, the Darwin Awards are a riot!

cloudhidden (author)2009-02-06

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

hammer9876 (author)2009-01-22

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.

Creativeman (author)hammer98762009-01-23

Thanks. Cman

mogimbu (author)2009-01-22

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.

Creativeman (author)mogimbu2009-01-22

Thanks mogimbu...your piece is very impressive! Lots of cutting huh? Cman

duck-lemon (author)2009-01-21

This is great, wonderful use of supplies and resources. That's some very creative work there creative man! **subscribed**

Creativeman (author)duck-lemon2009-01-21

Thank you very much DL. Cman

KEUrban (author)2009-01-21

Great idea... A good combination of technique and creativity!

Creativeman (author)KEUrban2009-01-21

Thanks KE. Cman

Gonazar (author)2009-01-20

shouldn't it be the other way around? Text carved out of the stone? its alright if you leave the paper, then it gives a metal text look, but if it's carved text then you should use a stencil

jackcday (author)2009-01-20

I'm not very font-wise. Which font did you use for the gothic "Stone" text? Great instructable btw, I'm gonna make a massive gothic "carved" J for my room. :D

Creativeman (author)jackcday2009-01-20

Thanks...not sure about the font...maybe times new roman, bolded? Cman

About This Instructable




Bio: Retired, doing art work now. Great. Have the time and the money to spend doing what I want to do.
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