About my love to expanding foam
    Published on Oct 3, 2010

    In the last time there were a lot of people who asked me how I create my expanding form figures and and it is just amazing that these people came from all over the world! It’s great to hear that you guys like my technique so much and want to try it by yourself. So I want to make it easy for you and try to explain something about my work with this awesome material.

    At first: I use expanding foam from cans and I always choose the cheapest ones. My home depot is “Obi”, but expanding foam is a base material for home building so you’ll find it in every other home depot.

    Better buy too much than too less cans. I mostly buy something between 5 and 10 cans and hope that it will be enough for the next days, he he. Shake it well before you start to work with and cover your ground with a sheeting or something else. You will be not happy when you get this stuff on your clothes, your carpet or your floor.
    Then, you have to know that it can be difficult to find the right form in the carving progress. It’s easier if you have a help. I draw my form on card board, cut it out and then I cover it with expanding foam.

    You have to wait some hours until the foam gets dry and you are able to carve it. If you spray a bit water at the foam then this process will be accelerate.
    When it’s finally dry you can go to work. For carving I use normal cutter like this:

    It’s better to buy cheap ones and a lot of them. Sometimes I need about 10 or 20 cutter for a project, because I cut in foam when is still not dry inside and the cutter gets dirty and sticky. I clean them after half an hour or change them because they are not sharp anymore after too much carving.

    When you start with carving try to carve a clean surface at first. Try to find your final form and search for the grey board inside. I cut some time as deap as I can inside of the foam and then I cut everything I not need away. It’s better to split a complicated form in more work steps. As you can see I also carved at first only the head of my staff.

    Then I added further foam to carve the horns and the spikes on it’s back. Here my fault was, that I was just too lazy to add some card board inside of the new foam. So it was a bit hard to find the right way to carve it. Later I noticed, that I also need card board for stabilisation. The foam itself is very breakable and for smaller parts a finishing layer of newspaper and paper maché wouldn’t be enough to save it from damage.

    Here you see the finished carved foam. I guess I needed about 10 cans for this result. Mostly only 30 % of your sprayed foam is for your prop itself. The rest is dirt. A lot of dirt!

    He he, I don’t like trash bags so much. :)

    Here is a other example for the right use of card board inside:

    You’ll find card board inside of the eagle head and the spikes. By carving such little details it’s almost impossible to disclaim for help.

    If you’re done with the carving step we have to speak about the 3 final layers to save the foam inside: Masking (or painters) tape, pieces of newspaper and paper mache.

    Here you see all 3 layers. But why do you need them?
    Masking tape (or crepe tape or painters tape… oh, I hope I finally found the right english meaning!) covers the holes in the expanding foam and gives you a surface to work with. Layers of news paper parts give it a strong, solid and protecting coat. And paper mache makes your surface smooth or give you the chance to carve details or to model something. But try to find your final form while the carving process of the exanding foam. The better your base is, the less you need to model with paper mache and the less is the weight of your prop!

    Don’t save time for the news paper layer and be sure that it’s the most important one!

    And be sure, that the paper mache layer will need also a lot of time. I use a hot air gun to accelerate the dry process, but you have to take care if you use it, too. Too much heat and you’ll get ulgy air holes inside of your paper mache. So blow-dry a bit until the paper mache gets white (it’s grey when it’s still wet), then wait until the water inside make it’s grey again and keep on drying again. When your prop is finally covered complete with paper mache you can sand it and search for mistakes you have to correct. I use for sanding sand paper and a Delta sander. Then sand and sand and sand and add some details if you want to:

    And after some time and patience you can finally paint your prop! Have fun! :)

    I hope you understood everything and if you still have questions feel free to ask!

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    Written by Benni

    | Writer, Full-Time Costume Maker

    We are self-employed artists, writers and costume makers currently living in Germany. We love to help the crafting community by creating YouTube videos, writing books and by sharing the current progress of our projects on social media. In our shop you can also find crafting patterns to help you with your own projects!

    64 Comments

    1. Hello thank you for this tutorial. I am helping my daughter with her satyr costume and thought we’d try this foam to cover the wire we have over the shoes for the hooves. Planning to carve the shape then paint. Do you think it will be strong enough without the paper mache? I’m scared it may chip throughout the day walking around. If so would you recommend a primer first before the paint?

      Reply
      • I wouldn’t recommend skipping the paper mache. It really gives it a nice smooth finish and makes it easier to paint. I personally am going to use a primer, just wood glue, on top of my paper mache, then paint, then a finish/sealant. Good luck!

        Reply
    2. thankyou so very much for this tutorial it was perfect for my college final major project as I was making a full Krampus costume and used this method for the horns!!! thankyou so very much again

      Reply
    3. My son needs to wear a donkey latex mask in a play but the director is afraid it will muffle his voice. I thought of cutting the mask at the mouth, but then the lower part would flop. Do you think I could spray foam inside the donkey nose, let it dry, and then carve it to fit his face? My hope is this would give some movement to the mask when he talks. Your thoughts? Thanks!

      Reply
    4. Might want to also play with using the uro foam to glue PS foam together for a more stable medium. Hot wire cutters for basic carving followed by normal tools.

      Reply
    5. Hallo Kamui! Mein Name ist X’ena wie “Xena the Warrior Princess”. Mein Deutsch ist ein bisschen schlecht, aber ich war nur drei Jahre gelernt. Ich komm von Youtube. Danke für die schöne Tutorial.

      Reply
    6. thanks to your amazing tutorial i got the courage to make my own expandable foam prop. its valor from (quinns bird from league of legions) The only issue i have is i have large holes that are not able to cover up with tape. do i just fill them in with more foam and then cover it with tape? I also was wondering how do you attattach thing like a dowl rod in the foam after the fact? Do you use glue? if so what kind?

      Reply
      • You should sharpen the dowl rod to a very sharp point . After push it in to where you need it . Then take it out and glue the inside of the whole and the rod after glue around and add tape and paper mache

        Reply
    7. where can I find this expanding foam and I love the work you do is really cool I love congratulations

      Reply
    8. I’m currently working on Dante’s rebellion sword and I have the carved expanding foam structure done. But I’ am really confused about the layers? Which order do the layers go and what do I need for each layer? I have paper mache all ready to go but I don’t want to put that over the expanding foam prop and then realise I’ve done it wrong! haha.

      Reply
    9. Can you paint onto the foam itself and skip the paper mache? Its texture is perfect for a prop I am working on.

      Reply
      • I have spray painted the foam. No problems.

        Reply
    10. Is there another substance you can recommend if I can’t get my hands on paper mache powder?

      Reply
      • All you need is glue and water or flour and water…save the money on actual pm powder

        Reply
    11. Hello Kamui.

      Thank you very much for your tutorials. I am working on a test project with your methods after watching many of your videos and if it works well I will be using it for a cosplay I want to do this year. It is a small sword and so far I have had very few problems except for the foam pushing the core, deforming it a little. It was not too hard to fix, I just cut the foam, re aligned it and put more foam in.

      I have a question regarding size, is this many layers strong for roughly 180cms tall scythe? I imagine it is a little taller than your staff but the blade for the scythe extends really far out.

      Sorry if it was stated earlier, I might have missed it, but is you paper powder mache pre mixed or do you get powder, wallpaper powder and mix it manually with water?

      Last question, when using wallpaper glue mix (I could only find it in powder form) I got lots of chunky powder bits, did you ever have problems like this?

      Thank you again, I shall look more at your tutorials for more ideas :D

      Reply
      • I haven’t used the wallpaper powder but I’m definitely going to try. I’d recommend getting a cheap hand held mixer, or even try sifting your powder first. I find cold water also usually helps with not forming clumps, not sure why, but warm water just makes everything want to stick together. If you’re still worried about clumps, I would mix the stuff and then strain it through a sieve (very small holed strainer, almost like a screen, but not as fine as cheesecloth, that would clog up)

        Reply
    12. HI Kamui,
      What great tutorial/site. I saw yourr stuff on YouTube after Googling for “expanding foam models.” I am building a scarecrow for a local competition and decided to try Foam Modeling. I decided to make a Croc, but my 4 and 6 year old girls want me to make a Dragon! So I am using chickenwire as a frame firstly adding papier mache (paper strips dipped in a Craft Glue and water 1:1 mix) over the wire, leaving to dry. I’ll add 3 layers, but wanted to use foam to get a dragon’s chest and belly. I wondered whether you had any advice or recommendations?

      Reply
      • Well, you can keep on working like this. Use the chicken wire as a base, cover it then with expanding foam, carve it and cover it then with paper mache. Just like in my video. You maybe need to experiment a bit, but thia was also the way how I made my Druid Tier 6 head piece. :)

        Reply
    13. Hallo Kamui! Hello Kamui!
      I wanted to ask how much cans you need for a whole armor?
      If you used 10 cans for a single staff, then it will be rly expansive, won’t it? Oo
      I went to Obi and found cans with 22 L – which cost 16 Euro per can!! o.o Thats rly expensive! It was a foam of a known brand, maybe thats why the price is so exaggerated. But i didnt found this “Montage Schaum” that your picture is showing. How much does it cost? Where can i find it?

      You’re doing a great job!
      Would be nice if you could give me some information :>

      Reply
      • Oh, well, that pretty much depends on what you want to build. I can tell you that one can is able to fill about one bucked full with expanding foam. I usually don’t use more than three cans for a staff and one can costs 5 Euros in Germany. It’s from the brand Lugato and I buy it at the German home depot called Obi. So I don’t really have any problem with the costs of this material.

        Reply
    14. Awesome inspiring work here! Just a few questions though:

      – What paper powder do you use and where do you find it? A craft store? Home depot? I’m very unfamiliar with it, so I don’t know where to get it or how to use it lol.

      -Do you just mix it with wallpaper glue and water? Or something else? Maybe I misunderstood.

      -Is it more moldable than actual paper mache? I read somewhere it almost becomes like clay. Any specific tools or methods you use to apply it to the newspaper layer?

      Reply
      • Thanks a lot!
        I find paper powder at the home depot and my craft store, but since I live in Germany names won’t help you. I’m sorry!
        No, I mix it only with water. There is already glue mixed in.
        Hm… I never worked with any other paper maché, just this powder stuff. I apply it only by hand and with some water on my fingers.

        Reply
        • Not sure if this helps now but I just found out that the paper mache you refer to is called paper cay in the UK.
          Great tutorial cant wait to do my first cosplay.

    15. hi! i really love your things, i scanned on your blog, facebook, and youtube, and i really want your style sooo much.. by the way, you look really gorgeous in cosplaying. well, im not really an artist. =D
      i have some couple of questions.
      1 – is it necessary to use more expanding foam? (i mean to cover it more? since its expands bigger.)
      2 – i wanted to ask what type of paint you use on painting?
      thanks for the informations!

      Reply
    16. Thank you for posting this! I’ve been looking for an easy and cheap way to make Draenei horns from World of Warcraft. Latex seemed too complicated and premade ones were expensive. This is perfect!
      That cardboard form helps so much too.
      Oh, and your English is better than many Americans I know! Keep posting!

      Reply
    17. Is there any effect when putting expanding foam in a styrofoam?

      Reply
      • Hm… I don’t think so.

        Reply
    18. I’m having the same problem as Erik Watts is with the foam degassing/deflating. I’m also curious if I’m not waiting long enough before carving. I waited a full 12 hours before I carved it out and it degassed/deflated.

      Reply
      • I start carving when it’s also dry inside and never had this problem. Many people I know also work with expanding foam. Maybe it’s better to try a different brand?

        Reply
    19. I keep carving my foam but the next day it is caved in around the cardboard. like the foam deflates. Am I just carving it too soon? I have been leaving it on my porch overnight. would that matter?

      Reply
      • Hm… never had this problem. Maybe you should try a different brand of expanding foam.

        Reply
    20. Wow this is so amazing!! :D Just curious when you mix the paper powder and the wallpaper paste powder with water, how much do you mix in of each? Like how much paper powder, wallpaper paste powder, and how much water do you mix together?

      Reply
      • Hm… I just follow the instructions on the packaging. All I need to do is just adding some water.

        Reply
    21. I’m thinking about using spray foam to make some simple UFO costumes for a children’s play. Do you think I could spray spray foam inside a rubber swimming ring to give me the basic shape? Would the spray expand inside a rubber shape, do you think? And would it dry? I also need to make two astronaut helmets. Could I get a basic shape by spraying foam over an inflated balloon and then carving/sanding smooth? Any advice would be very welcome!

      Reply
      • Hm… I really don’t know. I always thought that it needs to dry and so it needs some air. You need to try if it will work or not.

        Reply
    22. Hello, I don’t know if you have been asked this yet, i scanned through your comments before deciding to ask. I’m going to be making shoulder shields from Final fantasy 8 from the characters Raijin and Fujin, and i was wondering what you would use for the base, under the expanding foam. Cardboard? and if so how do you get it to form around your arm, like in a U shape, like the picture about of the arm armor? Thank you! I love your work!! :)

      Reply
      • i was wondering the same thing

        Reply
      • I use for my pauldrons mostly a base out of a styrofoam globe. But surely you can also use cardboard, Wonderflex or any other material which will fit to your shoulder. Since you will cover it with expanding foam, you don’t really need to take care for the material. Just try to form a good bacis for your pauldron.

        Reply
    23. I’m sort of confused….. Sorry, but if I made a huge…. like roughly 4 to 5 feet weapon, what would I do? Other than the expanding form, do I use all three layers, or which layer…?

      Reply
      • not kamui , but maybe u check it and i helped u:

        as one of the above posters said, you could get the special foam glue and or you use all three layers kamui described: I am working at a shoulder pad atm, and the results of all three layers is quite acceptable – durable and paintable

        Reply
      • The bigger the prop the more important it is to make it solid and strong. So better take care to use a thick layer of news paper pieces to avoid that your weapon will break.

        Reply
    24. would this work with making cosplay armor?

      Reply
    25. You are a wonder, my dear! So much creativity and adventuresome experimentation! Thank you so much for sharing what you know. I am certain that you have inspired many people to try things that would have seemed too intimidating without you acting as a guide! Well done!

      I wanted to share a bit with you in return. I am a props designer and costumer for theater and opera here in Oregon in the US. I do a fair amount of work with foam myself! Something I learned from another wonderful props maker was a light and flexible way to cover foam and create a base layer for whatever needs to be put on it. There’s a product often called Flexglue. It’s a water-based white glue–fairly non-toxic stuff–that gets painted on all over the surface of a foam shape, and then cheesecloth (or plain muslin) is applied to the glue to cover over pits and holes and to provide a more even surface. Then another layer of glue is applied over the cheesecloth to ensure even adhesion and to help fill in the weave of the fabric. When completely dry, the surface can be examined for any imperfections or too much visible weave, and more glue can be applied to help fill that in. It makes for a flexible, forgiving, durable surface that can then be painted or have other design elements glued to it. If pigment is added to the glue, some very nice color effects can be achieved.

      If you’re wanting a tough, durable surface, Foam Coat is fantastic stuff. I’ve seen props made with Foam Coat survive national tours. It would certainly survive any rough-and-tumble at conventions if used on armor or weapons. The resulting surface is not flexible at all, but sometimes that’s just what is needed.

      Another option is a product called Sculpt-or-Coat. It can be used as a sculpting medium on a surface, a foam coating or an adhesive (or all three at once!). This stuff is magnificent for creating textured surfaces and does not get as hard as Foam Coat.

      These are all commonly available from theatrical supply businesses in the US. I imagine they are also available from similar suppliers in Europe or products very like them.

      I hope these might provide some fun for you and perhaps lighten the overall final weight of your projects. These products have saved my hide as a props maker many times. I hope you may find them just as useful!

      Again, thanks for being so awesome! :D

      Reply
      • Thanks, Kamui, for the tutorials! And thanks, Andra, for the extra tips!

        To Andra, you mentioned Foam Coat. I will be making a prop out of expanding foam. If I were to use Foam Coat over the foam, is there anything else I need to do? Is it as easy as coating the expanding foam (once sculpted of course) in Foam Coat? I just want to make sure I’m not missing any steps.

        Reply
    26. What? How could it magically turn plaster-white? I’m so confused! But it really does look good.

      Reply
    27. looka like sheet

      Reply
    28. Wait…
      This is absolutely wonderful but can you give me a list of the materials you’ve used here?

      Reply
    29. Yeah, I use wood as core for my weapon, Rhia and I never tried something else, but I’m sure there are more possible materials. However at coventions in Germany it’s just not allowed to carry these kind of weapons not for the convention halls itself. It’s allowed to wear them outside and so I never worried about it. If it’s the same in your country it would just recommend not to carry any weapons inside. There is less space for photos and you need your hands for something better than for your weapons! :)

      I’m really glad that I was able to help you, Clayton! Thanks for the great feedback! :)

      Reply
    30. This is awesome, thanks for the tutorial! I’ve been busting my ass working on a costume in time for AB (Zoma from Dragon Quest 3, you can see the reference here: http://momoja.blog61.fc2.com/blog-entry-463.html), and this has been really good for the helmet, and probably will be for the shoulders and other bits as well. Thanks again!

      Reply
    31. I absolutely LOVE your work. I am trying to redo my cosplay weapon from last year. I started with a large piece of styrofoam and it ended up breaking into so many pieces that not even duct tape could fix it. Now I would like to try your way of making weapons. However it seems like the core of your weapons seem to be some kind of hard wooden material, however at the convention I am going to, they do not allow hard wood cores. Do you have any suggestions as to what to use as a base for my sword that will keep it strong enough but will not be to hard? Thanks.

      Reply
    32. No no, paper mache consist of paper powder and wallpaper paste powder. And then I mix it with water. I guess you can buy paper mache or paper clay in every hobby store.

      Reply
    33. When you say that you mix the wallpaper paste with paper powder. Where do you get this paper powder to mix it with?

      Reply
    34. Thank you! Great to hear, that you like it! :)

      Reply
    35. Thanks, very informative, Il be frequenting you blog from now on :)

      Reply
    36. He he, now you see the problem of the language barrier. I try to explain everthing as good as I’m able to, but then there are stupid words like this…
      Like you noticed right layer 2 is only newspaper stripes dipped into wallpaper paste.
      But layer 3 is a mixture of paper powder with wallpaper glue. If you mix it with some water it became a tough, sticky clay, which you can model a bit. It this stuff: http://img512.imageshack.us/img512/4593/t8ranke5.jpg
      The problem is, that the newspaper doesn’t glue on expanding foam. So you can work only with the last layer, the paper mache. But then your expanding foam inside will break easily. Or you use all 3 of them. And if you have large props, be sure that with only one expanding foam layer your prop can be have more weight, because the paper mache will also fill the holes of the expanding foam.
      And no, I’m very satiesfied with wallpaper paste and I guess it’s also the standart way to work with newspaper, so I never used something else.
      I hope everything is all right now! :)

      Reply
    37. Since there was no edit button, Il just make a new post for the other question I had :P

      The first layer (tape) seems kinda superflous, wont the newspaper cover it on its own?

      Also, have you ever tried using wood glue mixed with water as a substitute for wallpaper paste?

      Reply
    38. Hi! First of all, very awesome work :)

      Now, I wonder what you use for layer 3? You mention using Papier mache, but in my experience thats your layer 2, newspaper bits dipped in wallpaper glue.

      Your step 3 seems very similar to latex filler. But since this requires several layers and is kinda expensive, I am very intersted in the exact recepie for layer 3 :)

      Reply
    39. Oh, I just using wallpaper paste for this step. ^^

      Reply
    40. So for the newspaper layer are you gluing it on over the tape layer? If not, how are you attaching the newspaper layer?

      Reply
    41. Great to hear that! Thank you! ^^
      Spraying water on the foam will make it dry faster I meant! But I often forget this, so it’s not so important! ^^

      Reply
    42. Thanks so much for the tutorial! >o< It's very helpful~~!
      Just wanted to clarify something…
      Where you said “If you spray a bit water at the foam then this process will be accelerate.”

      Is that saying that spraying water on the foam will make it dry faster, or that spraying water will make it carve easier/faster?
      Just making sure :3 It’s right in the middle of the two steps so I’m not sure which it applies to.

      Reply

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