Make Foam Look Like Carved Granite!





Introduction: Make Foam Look Like Carved Granite!

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

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

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

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

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

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

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.

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    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?

    7 replies

    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.

    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!


    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!

    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.

    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

    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.

    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

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

    1 reply

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

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

    1 reply

    No, only use eps foam or styrofoam!

    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!

    2 replies

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

    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...

    great   i will try it   thanks a lot

    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.

    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...