I have been hearing and reading a lot about foam

Discussion in 'FAQs' started by who_dat73, Jan 25, 2005.

  1. who_dat73

    who_dat73 Member

    Just wondering before I get to far into this what kind,thicknes and where do I get it. From what I have read it seems like its a good idea since I want to put streams and stuff into the layout so I would carve them out.

    Thanks for the help and all the info you guys provide to everybody:)
  2. Bikerdad

    Bikerdad Member

    KIND: You want extruded polystyrene, not expanded polystyrene. The former was originally created under the brand Styrofoam by Dow Chemical, is blue, and is joined by the pink extruded foam from Owens-Corning. Expanded polystyrene is the same stuff as the beer cooler you took to the lake last summer. It does not have as much structural strength, nor does it machine and shape as well for our purposes, as does the extruded polystyrene.

    THICKNESS: Extruded is available in thicknesses ranging from 1/2" up to 4", perhaps more. It can be had in a wide variety of structural characteristics, depending on the application. For MRR purposes, the "garden variety" foam is sufficient. You can use any thickness you want, it simply a trade off of how much you have to "build it up" (using only 1/2") vs. how much you have to cut away, depending on your needs. Most folks go with 1".

    WHERE: If you happen to live in the Frost Belt, you can usually find it at most lumber centers, building supply centers, and home stores (aka Lowe's, Home Depot, etc). In the Sun Belt you have to look a little harder. If the above strike out, a definite possibility (call around), contact commercial insulation suppliers. Real Styrofoam is widely used in commercial refrigeration installations.

    BONUS: If you live in Southern California or the NYC area, you can also go for theatrical Styrofoam products. Styrofoam is widely used for sets and props, being easy to work, lightweight, breaks nicely without hurting folks, etc. Availability of this type of foam outside of those two areas is unknown to moi.

    Enjoy working with foam. Make sure you have a shopvac handy.
  3. who_dat73

    who_dat73 Member

    thanks for the advice biker

    I think I like this whole idea I was thinking that I was gonna have to build all the terraine by hand this sounds much more easer to work with :thumb:
    By the way what kind of bike you ride?
  4. railwaybob

    railwaybob Member

    If you want to see how to build your layout using styrofoam (this is the stuff that is either blue, pink, or light green in colour - never use the white stuff) visit my website, click on DCC and then select how to build a module.

    While styrofoam has been around for quite a few years now, it has not been readily accepted as a medium for making scenery. The standard still seems to be that old standy - plaster. Which is okay if you're not trucking your layout around all the time.

    Since I belong to a "module" railroad club http://www.hotrak.ca
    it's very important that my modules are as light as possible. This is where styrofoam fits the bill. I use styrofoam for the deck and for making the hills and mountains. It comes in sheets that are usually 2' x 8' and from 1" to 4" thick. You can stack it and glue it together using either wood glue or a polyurethane glue (polyurethane glue is real neat!)

    The old ways of carving the styrofoam told you to get one of those "surf-form" files. Don't!! This creates tons of electrically-charged crumbs of styrofoam that stick to everything. Which is probably why the use of styrofoam has never really caught on. There are, however, other ways of cutting the stuff from a simple hacksaw blade, a utility knife, a butcher knife (the "de-boning" knife is probably the best type), to "hot-wires".

    If you're using knives to carve the styrofoam, be very careful! You can quickly cut yourself.

    I like to use styrofoam because, like a sculptor, I can stand back and see what the carving looks like against my layout, cut off a slice here, a chunk there, glue a bit more there. And, if I don't like the results, it's very easy to start all over again.

    Once I have my piece carved to my satisfaction, I glue it to the layout and blend the piece into the surrounding scenery with some ultra-light spachling compound. Once the compound has dried and I've built it up to match the surrounding contours, I take a very wet J-cloth and rub the spachling compound down to blend the new piece even more into the surrounding area (like plaster, spachling compound tends to dry in lumps and bumps).

    I then paint the piece I've added with some flat brown latex paint (the kind you get from your building supply store) (my colour is "underbrush brown"). A couple more coats and all of the pink (or blue or light green) has disappeared. If I want to add a few more nooks and crannies to the whole thing, I simply pull out my carving knife, or other tools and carve away. And then cover up the pink with the flat brown latex paint.

    From here on, I use the standard scenery techniques for the ground cover, ballast, trees, etc, etc.

    My only suggestion (in addition to sharp carving tools) is to have a large garbage pail close by as you carve each slice. Clean up the mess as you carve.

    And take your time to create your masterpieces.

    PS - To use polyurethane glue, spread a bead or two on the bottom of the piece of styrofoam and spread it as thin as you can with a 1" putty knife. Spray the base of your deck where you're going to add this new creation with water (use one of those spray bottles). Press the carved piece onto the deck and hold it in place for about 15 minutes. If necessary, add some weights (a couple of 1lb sand bags, a hammer, or whatever is handy). In about an hour, the glue has set and it's ready for the spachling compound.
  5. SteamerFan

    SteamerFan Member

    extruded foam is the way, 2" is good enough for a base, Linn H. Wescott's book "How to build Model railroad Benchwork, 2nd ed" has a section in the back explaining how to build a setup for foam, suggest you pick it up and check it out.
  6. Connor

    Connor Member

    I've not built my bench work yet. I was looking at doing a 4x8 layout using a 1x4's for the frame and using 2 2" Thick foam sheets from Home Depot. Was going to put 1 IN the frame so that it's surrounded by the 1x4's and then put the other on top for my valley/mountain scenery. Or I'm going to just use a plywood with 1 sheet on top.. I'm looking to be having to move this thing a few times so I was thinking the all foam would be easy to move... But, I like the plywood as it makes the frame more ridged... I wonder how much heavier the plywood is vs the foam..
  7. Doc Holliday

    Doc Holliday Member

    A published estimate is that plywood is approximately 25 lbs. per 1/4 in. of thickness, thus a 4'x8' sheet of 1/2" would be about 50 lbs. While this seems a little heavy, (i've never weighed a sheet) it is way more than foam which is approximately 5 lbs / inch thickness for a 4' x 8' sheet (if my math is correct).
  8. railwaybob

    railwaybob Member

    If you're planning to move a lot, styrofoam is the way to go. If you're planning to make a sandwich of the plywood and the foam, if you use 1/2" plywood, you'll be defeating the purpose.

    The key is to make a frame using 1" x 4" or 1" x 6" knotty pine with crosss members every 2 feet to support the bottom of the styfooam. The cross members are 1" x 2" knotty pine. Use a 2" sheet of styrofoam and glue it into the frame (check out my website for construction techniques). You can glue the styrofoam to the frame using some wood glue, or polyurethane glue.

    You will end up with a frame for your layout that is light but very rigid. As a comparison, the next time you're into your favourite building supply store, try lifting a sheet of 1/2" plywood by yourself. That's how much your layout will weight and then some more when you add roadbed, track, etc. Then, for comparison, get 4 pieces of 1" x 6" x 8' knotty pine and two pieces of 2' x 8' x 2" styrofoam and compare the difference in weight.

    When you lift the plywood, make sure you don't get a hernia.
  9. Connor

    Connor Member

    I went to Home Depot today and looked at martials. They have something there called Lauan.. A very thing sheet of plywood looking martial (moisture resistant).. It looked rather light...
  10. Connor

    Connor Member

    Railwaybob, Your site doesn't want to come up.. Your hosting provide having issues?
  11. SAL Comet

    SAL Comet Member

    Ha Conner, Lauan plywood is used mostly as underlayment for vinyl flooring. As underlayment it only needs to be flat not strong. The 2" foam board is much stiffer than 1/4" lauan or even 3/8".
  12. Connor

    Connor Member

    I think I've decided on doing 2 2" foam. Just need to build the frame so that it won't crush the foam that's inside the frame.
  13. railwaybob

    railwaybob Member

    Just found out my website is down. It will be up in the next couple of days.
  14. Bikerdad

    Bikerdad Member


    I ride a Honda ST1300, Triumph SprintRS, Santana Elan, Diamonback Apex, and Schwinn 503?? roadbike. The last three haven't gotten much use in the last few years. :(

    There is one good non-structural reason for going with a plywood underlay. It simplifies mounting switch machines and various other doohickeys that go on the underside of the layout. :thumb: If you do this, you don't need anymore than 1/4" ply, and yes, you can use 1/8" luan, as nothing being mounted should ever be subjected to much stress.

    If you want to play around just a bit with shaping Styrofoam, you can go to a craft or floral supply place and get some of the green stuff they carry. The craft foams are also available in white. As long as its extruded, color doesn't matter.
  15. Connor

    Connor Member

    Don't think I'm going to be using under-the-table switch machines as I'll have that 2" thick foam to go through.. Also, another question... What's the best or pros/cons on using cork vs Mastic tape vs that other black foam looking stuff for road bed??

    Thanks, Connor
  16. spitfire

    spitfire Active Member

    Connor, there are 2 reasons for using roadbed.

    1) to give the track a prototype height (which they did for drainage) especially on the mainline
    2) to dampen sound from resonating due to the plywood

    If you use foam for your base, you won't need to worry about sound, as it deadens it quite well - another reason for its popularity. So, the only concern is looks and price. I believe the Woodland Scenics roadbed is a lot cheaper than cork. There also instant roadbed. I've never used it but I've read many times that it's not recommended.

    Another thing is that not all roadbed was the same height. A lot of HO modellers use N-scale roadbed, because it's not as high. Also, a lot of industrial areas, and yards, didn't have much ballast at all and don't need any roadbed.

    One thing about N-scale roadbed in HO - it has to be spilt apart to get the right width, and the space filled in with cut strips.

    Hope this helps.

  17. railwaybob

    railwaybob Member

    Just to let you know that my website is back up in case you want to visit it and get some ideas on the use of foam for the deck.

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