With the exorbitant cost of extruded sheet styrofoam, it seems possible that modelers could realize the benefits of styrofoam, (weight, ease of carving, ease of tearout) while avoiding some of the high cost, by using the expanding spray styrofoam now becoming popular for use in the building trades.
Anyone ever tried this?
How long does the sprayed foam remain pliable enough to shape before hardening?
How messy is the process?
How well does the dried insulation carve?
Is the expansion unmanageable, or can it be controlled well enough to create finished terrain? Rough terrain that can be finished with ground goop? Terrain blocks that can be carved into the desired shape?
It seems to me the process would be similar to creating a mountain out of shaving cream, that eventually dries to shape, able to be shaped to at least some degree before hardening, and the main problems might be poor carvability, liquid mess before curing, or uncontrollable expansion.
If no-one has tried this yet, I have a lift out section of terrain under construction I will volunteer for the process, but if it's already been tried and failed for whatever reasons, no sense in wasting time.
What does the MR collective have to say on the subject?
I saw this within the last year on someone elses layout. It was messy, and hard to control the expansion....by the time it could be molded into various contours, it had to be cut (defeating the original purpose of trying it...easier sculpting)
Only suggestion I can give is keep a dropcloth handy...:)
Bob Berger, C.O.O. N-ovation & Northwestern R.R. My patio layout....SEE IT HERE
There's no place like ~/ ;)
Hi,
I just searched this and came up with this link:
http://www.trains.com/trccs/forums/90467/ShowPost.aspx
hope it helps
Frank
"If you need a helping hand, you'll find one at the end of your arm."
All future terrain on our layout has to be removable to access staging, and the technique we used so far is carved extruded foam, with overlapped plaster cloth and lightweight spackling compound to hide the joints.
In one area, I'm using luan plywood suspended on drilled dowels friction fit into the main benchwork, and styrofoam scraps for rough terrain structure, which will be covered in additional plaster cloth and goop. Since the entire module is removable, a rough pile of spray styrofoam could be used in place of cut sheet foam,and applied outdoors to get around the mess.
I've never used the stuff before, so the obvious questions involve how runny it is before hardening, whether or not it will hold a rough mountain shape when dried, how well it carves after drying, and how the costs stack up per unit volume relative to sheet foam.
I know the stuff expands forcefully and can crush "formwork" if this is not allowed for, but if it will hold general shape enough to achieve a 45 degree slope angle, one or two sides could be "sectioned" with simple cardboard or even fascia if you were willing to make the fascia permanent there.
I've held off buying more sheet foam because I either have to cut it, or risk breakage while transporting it long distances on the roof carrier of my truck. If I can find a spray can of the stuff for not too much expense, I might try it just to see what happens, unless of course, someone raises additional problems that would make it a waste of time. Nothing to lose except for time and the cost of one can, if it doesn't work, I'll just cut it loose and re-do it with stacked sheet foam.
Used it in my prior life as a contractor, and tried to use it ONCE on the layout!!
1. You get a very small amount for the buck
2. It sets up too fast to do anything with it
3. It has to wear off anything it gets on - got it on a new pair of jeans - threw them out a couple of years later with the goop still on it
While working at Dunham Studios building large display layouts we used the same type of foam as is used by the building trades. I think the smallest quantity that could be ordered was 50 gallons (2x25). The professional product expands immediatly and can be carved in about 45 minutes. We used a low expanding product, about 2-4 inches - you still have to have some kind of substructure. The higher expanding is less dense (larger air pockets - harder to carve).
It's great stuff to use, but not very economically practical for small to medium sized layouts.
BTW with any type of spray foam, it has to fully expand and harden before it can be worked (carved). It acts like a suffle and collapses if you try to shape it before it's fully cured. It will stick to anything in it's semi-liquid/soft state and it's very difficult to remove.
On my home layout, I have used foam-in-a-can, (like Great Stuff), mostly to blend the pink and blue extruded styrofoam layers or build up some smaller areas. A can can cover an area about 2x3' 3 or 4" thick. To carve rock formations, the extruded foam carves better than the foam-in-a-can. Any carved areas of spray foam still has to be coated with something to close up the exposed air cells, (I use thinned vinyl spackeling compound).
I'll add some pics.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
Jeffers wrote-With the exorbitant cost of extruded sheet styrofoam,
Home Depot, last week-4x8x1"-$10, 4x8x2" $22. That works out to 32 cents and 68 cents/sq/ft.
I've used can foam for insulation. Bought 3 cans. 2 of them plugged up before they were half used. They don't seem to like it when you use them, let them sit, use them, let them sit. Seemed like the kind of thing that once you open it, you should use it all. IIRC, the cans were $7 each.
I tried the stuff and it wasn't worth the time and money.Personally I have had better luck with foam( the white kind"Yes") And better luck with plaster cloth.The spray foam stuff is everything that everyone has already stated...Very Messy, hard to control, and the work time is not worth the effort in my opinion.
C.c
Last time I priced extruded foam here, it was $35 per 2" sheet. I've got about 50 square feet of new layout, three quarters of which will be mountainous, call it 40 square feet. Call the ridgelines two feet high, divide by half because they are triangular in cross section, 40 cubic feet of foam, times 1.5 for waste, 60 cubic feet needed, 4 feet by 8 feet by 1/6th foot thick per sheet, 60 cuft total divided by 5.3 cuft per sheet, 11 sheets needed, times $35 per sheet, $380 give or take, plus tax, a round four hundred bucks.
Not a problem for a labor of love, however...
Each of 11 sheets has to be sliced lengthwise to fit in the truck, then spliced back together, most assuredly in the least convenient way to reassemble as mountains, plus the styro-grommets all over the house, hey, the spray foam SEEMED like a good idea, at least worth looking into.
Okay, so it's gooey, bubbly, sticky, messy, hard to carve, and WAY more expensive than sheet foam, exploration over, extruded foam wins by a landslide, nothing to see here, move along please.
How solid does Fix-a-Flat get inside a spare tire?
Readi-whip?
Cheese Whiz?
(Mmmm, mistakes can be EATEN...)
I've been experimenting with "Great Stuff" window insulation foam, and it's cheaper knock-offs (Red Devil). The benefits of this "polyfoam" is that it is more durable and flexible than extruded foam insulation, which I'm also using. That's the fundamental difference, it's polyfoam, with polyurethane.
My experiments - right now, it's just that, I'm playing with a small "diorama" section before committing it to my layout - have revealed a couple of things about Great Stuff-
1) You have to carve it. It's not mountains from a can, unless you want you mountains to look like whipped cream. And it expands considerably and unpredictably, so you really can't control it into shape. But if you lay it on lightly, in rows and layers, you can learn to control it in depth. Lay it in a depth of about 4 inches, and then carve to suit. It does not carve well into final rock shapes, for there are serious air pockets; hence it needs sealing. It does, however, make a nice scenery base, especially for access hatches and tunnel coverings because of its flexibility and durability. It sprays in place and stays and flexes in place.
2) You need a good structure base underneath it...window screening works, and I'm also using cardboard strips with shelf liner covering that. Because the stuff, you don't want it to get on any track underneath the tunnel, and it will fall and seep through anything with large netting...so keep the sub structure something with tight netting that prevents it from seeping through.
2) I will then glue foam rock formations on it, as I am concentrating on the Great Stuff for removable access hatches where the merits of the polyfoam's durability and flexibility will be made use of. I don't want to use hydrocal cast rocks there because of the abuse the area will inevitable get. I think the foam rocks and polyfoam base will stand up better.
3) It is extremely messy and sticks to everything...except slick plastic. Well, its adherence is also one of it's advantages. Wear gloves, use disposable tools (I've been using a wood shim to help it spread about). It contains pretty well though, so you don't need massive drop cloths. just some thing for the general area surrounding where you are using it.
4) it cuts well and cleanly with a fine tooth saw or paring knife. No little beadboards falling about. Cuts better than extruded foam, I think. You can seal and fill it with diluted wallboard compound. Great Stuff is very flexible when it cures, you can bend it.
5) If you put a can of Great Stuff in the refrigerator for like 45 minutes, it comes out expanding less. Only expands to like 3 times its initial size. A good tip from the Bragdon site.
It has its uses. I wouldn't use it for a whole layout, but for special situations, like access hatches and areas where you need a firm, durable and flexible structure.
I've looked at Bragdon and Mountains-in-Minutes (Isle Labs). That is the same polyfoam, I think, but a two-step process with an activating agent, like using an epoxy, that makes the expansion more controllable. But that two step process seems quite a bit busier and messier than using the Great Stuff out of the can. Plus, they make "mold release compound" which enables you to use the polyfoam to make foam rock castings, which is nice. But bottom line, the two-step stuff is expensive, like 50 bucks for a kit. It doesn't look like a kit is going to get you any farther than 3 cans of Red Devil at 3-4 bucks each.
Just what I"ve found out so far. Hope it is of some modest interest.
I have used Great Stuff in our club layout as a foam glue, between two or more sheets of styrafoam. It doesn't expand vertically in this manner, but rather horizontially and so a little bit can go a long way. I also use it as a crack filler between the plywood and the stryfoam sheets. As mentioned it is flexible so it very forgiving in moves.
The only type of rock that I can think of that spray foam could easily represent is pahoy-pahoy lava. But I don't know of a lot of North American railroads that are built on or around that stuff.
It has it's uses, just not in moutain building.
jeffers_mz wrote: With the exorbitant cost of extruded sheet styrofoam, it seems possible that modelers could realize the benefits of styrofoam, (weight, ease of carving, ease of tearout) while avoiding some of the high cost, by using the expanding spray styrofoam now becoming popular for use in the building trades.(1) Anyone ever tried this?(2) How long does the sprayed foam remain pliable enough to shape before hardening?(3) How messy is the process?(4) How well does the dried insulation carve? (5) Is the expansion unmanageable, (6) or can it be controlled well enough to create finished terrain? (7) Rough terrain that can be finished with ground goop? (8) Terrain blocks that can be carved into the desired shape? (9) It seems to me the process would be similar to creating a mountain out of shaving cream, that eventually dries to shape, able to be shaped to at least some degree before hardening, and the main problems might be poor carvability, liquid mess before curing, or uncontrollable expansion.If no-one has tried this yet, I have a lift out section of terrain under construction I will volunteer for the process, but if it's already been tried and failed for whatever reasons, no sense in wasting time.What does the MR collective have to say on the subject?
(1) Anyone ever tried this?
(2) How long does the sprayed foam remain pliable enough to shape before hardening?
(3) How messy is the process?
(4) How well does the dried insulation carve?
(5) Is the expansion unmanageable, (6) or can it be controlled well enough to create finished terrain? (7) Rough terrain that can be finished with ground goop? (8) Terrain blocks that can be carved into the desired shape?
(9) It seems to me the process would be similar to creating a mountain out of shaving cream, that eventually dries to shape, able to be shaped to at least some degree before hardening, and the main problems might be poor carvability, liquid mess before curing, or uncontrollable expansion.
(1) Yes, about 10 years ago and again recently to see if it is still as hopeless... it is...
(2) About 20 seconds or an unknown period headed toward infinity if the stuff decides not to do what it's supposed to... in this case the soggy mess is a disaster to try to scrape off... and it gets on everything... to which it then sticks permanently and cures rock solid...
(3) If you contain the stuff (like in spraying it into a wall cavity) not at all... but you need something like a wall cavity to contain it... any gaps in your wall and it will come straight back out... this should give you a clue what you are playing with...
(4) Don't know about the stuff once it's in a wall... some of it you seem to be able to screw things into pretty securely???... out of a wall it forms a smooth hard skin of varying thickness (mostly less than 1mm) ... inside that it is a honeycomb... again this varies considerably in texture... from tiny pores to great big holes.
I found that it could be easily cut with a fine toothed hand saw... cutting it into chunks... but anything else was pretty hopeless. Cutting with a knife (Stanley) needed a very sharp blade and was seriously dangerous.
(5) Yes.
(6) No.
(7) 1st experiment took paint... I made the mistake of painting it "earth brown"... guess what it looked like...
(8) Yes... sort of...
It cannot be used to infill shell scenery ... without making the scenery so massively strong that it wouldn't need infilling.
It can be sprayed into a box to make a block BUT there is no garuantee that any large piece will decide to ever cure... and (apart from the fact that you have to unstick it from the box... and I have had trouble with this with cardboard boxes that have a waxed inside finish)... you don't know whether the stuff has cured right through until you start to extract it from the box. Guess what happens with any uncured stuff when it gets out?
If that hasn't put you off the blocks can also form with large (like huge) cacities and no structural strength at all.
(9) Go back to (4) for cutting...
If I wanted to make a mountain like the one in "Close Encounters" I would not use this stuff.
SOMETHING TO NOTE...
All the variants of this stuff I've tried have an exothermic element in their process... i.e. they get HOT. Some of them get very hot... in a housewall this is presumiably no problem if the cavity is between bricks or brisck and plasterboard. Out of a wall, at an early stage, I have known it get hot enough for me to drop the box I was testing in pretty fast.
Just as explanation... I sometimes work at a place that warehouses the stuff so I've tried the stuff from undamaged cans in packs that have been spoilt and are being scrapped.
Sadly, although it seems like a brilliant idea... it doesn't work... at present.
loathar wrote:Jeffers wrote-With the exorbitant cost of extruded sheet styrofoam,Home Depot, last week-4x8x1"-$10, 4x8x2" $22. That works out to 32 cents and 68 cents/sq/ft.I've used can foam for insulation. Bought 3 cans. 2 of them plugged up before they were half used. They don't seem to like it when you use them, let them sit, use them, let them sit. Seemed like the kind of thing that once you open it, you should use it all. IIRC, the cans were $7 each.
But we're paying for the cubic foot - the sheets at least here that I've seen are sold as 48"x96"xn" (where n is the thickness). So a 1" thick sheet is (assuming my math is correct) roughly 2.67 cubic feet, and a 2" thick sheet is (again assuming my math is correct) roughly 5.33 cubic feet.
That means they cost $3.75 (rounding up) and $4.13 (rounding up) per cubic foot... assuming yet again that I remember how to do math.
-Dan
Builder of Bowser steam! Railimages Site
jeffers_mz wrote: With the exorbitant cost of extruded sheet styrofoam
Exorbitant? Have you priced quality 3/4" plywood recently? 2" foam seems like a bargain in comparison!
it seems possible that modelers could realize the benefits of styrofoam while avoiding some of the high cost, by using expanding spray styrofoamAnyone ever tried this?
Yes, I have. Keep FAR away from this construction method.
Never. In other words, you can't work the material, beyond the initial application. It's extremely tacky, and will aggressively stick to any tool you try to use to shape the goop.
Adding the spray foam isn't all that messy, so long as you get it exactly where you want it. Don't try to touch it while it's wet, and don't get any where you don't want it. If you do, you have to wait until it's dry and carve/sand the material away.
Horribly. You can CUT it, but you essentially can't effectively carve or sand it. Imaging a giant block of kitchen sponge.
Spray foam expands to 2-4 times it's initial size when sprayed out of the can, and it expands in pretty puffballs which look absolutely nothing like real terrain. The bottom edge will have an inward curve to it, which is again completely unnatural. And once you start carving the stuff, you quickly realize that the interior of the puffballs looks like Swiss cheese. Again, completely unrealistic.
Unfortunately, spray foam, like spray mount adhesive, is one of those products that SEEMS to be ready-made for the modeling community. Unfortunately, neither has any real use in building model railroads. I do use spray foam, but only as a way to fill largish gaps in chunks of foam.
Ounce for ounce, sheet foam is a much better way to build than spray foam. If you don't need the structural strength of the extruded pink or blue polystyrene foam, go with beadboard foam, which is cheaper still.
Ray Breyer
Modeling the NKP's Peoria Division, circa 1943
That's true and more accurate...you and CUT it, but not CARVE it. That's a good point of distinction I didn't articulate well.
I do think it has its uses though...when you need a durable, flexible sub structure for scenery, in limited stretches. It is not a final scenery layer, however, and should not be thought of as such.
I've used spray insulation foam as a jetty. It works well, but as someone said, it can get plugged up easily. I learned this the hard way and having to go and buy another can from Ace. As soon as you are done with spraying, immediately clean it out with a acitone (nail polish remover) or stick a wire or pipe cleaner up it and work it around.
As far as carving it goes, it is very simple and is like carving out foam insulation board. Obviously don't use the foam for the whole mountain, but stick a bunch of recycled foam boards underneath to form the basic shape and contours of the mountain and then later spray on the foam. Then carve out the foam. As far as messiness goes, I didn't have any trouble with it. Just treat it like spray paint, the harder you push on the nozzle, the more it comes out and the faster. I don't know too much because my project was relatively simple, but this might help.
lvanhen wrote: Used it in my prior life as a contractor, and tried to use it ONCE on the layout!!1. You get a very small amount for the buck2. It sets up too fast to do anything with it 3. It has to wear off anything it gets on - got it on a new pair of jeans - threw them out a couple of years later with the goop still on it
I agree with Ivanhen, I just got through using a can of this stuff to seal around some new construction. You must carefully feed a small amount of this stuff at a time because it expands many times it original spray amount. And don't get it on your hands or anyhting else where it doesn't belong!!!!! Talk about a sticky, hard to get off mess
When you consider the size of your home layout, the cost of a sheet of 2" thick, 2'x8' foam insulation board is not that expensive. $13?? What do pay for a locomotive? For 6 pieces of flex track? The cost of foam board is negligeable really.