Gluing foam to foam and cork to foam and track to cork... UPDATE

Model Railroader Layouts and layout building
1

I’m building a N Scale layout and will use extruded polystyrene foam to form the layout’s “earth.” The first layer of 2" thick foam will be glued to the plywood benchwork using the Liquid Nail product specifically designed for foam. However, I was surprised to find small print on the back of the Liquid Nails tube that said that it should not be used to glue foam to foam.

I’m guessing this might have to do with drying time. Any suggestions for what I should use instead? I’m thinking simple yellow glue.

2

I believe that the “foam to foam” application is not recommended because neither surface is porous. Yellow glue is what we use at the local modular club for gluing wood to foam, and foam to foam.

I have also heard that some spray adhesives work well, but you must test first to ensure that your chosen brand is “foam-friendly”. The advantage is that there is almost no drying time required. The yellow glue can take quite a while to dry between layers of foam…

Andrew

3

I’ve used two methods.

The first is wood glue. While it worked, it did give me problems in that it forms a very hard layer at the barrier. If you need to cut through this layer while doing final shaping, it can be difficult.

I’ve had better luck using latex caulk. The stuff that comes in tubes and uses a caulking gun. I’ve built an entire out of it with no problems. It forms a flexible layer that can be cut through with no problem. The only downside is that it can take a couple of days to fully cure. If you try to use a surform on it during that time, it will gunk it up pretty bad. It can be cut while curing without trouble and surformed once fully cured.

Dan

4

One thing that I have not seen suggested is to put a layer of cardboard between the layers of foam. That gives the porous material needed to provide reasonable drying times, but doubles the adhesive…

5

Iv’e used the liquid nails for foam on my layout with great results. Iv’e glued 2" foam to 2" foam of varying dimensions (up to 2’ by 4’) and have gotten very strong bonds. It just takes a very long time to dry. I’m so impressed by this glue that I also use it to gue the roadbed to the subterrain foam & I even glue my track to the roadbed with it. If your not sure about the liquid nails glue then use the woodland scenics faom tacky glue. I’ve used both and the woodland scenics glue also does a fine job of gluing foam to foam. However, this glue is expessive compared to the the liquid nails glue. It does dry clear which is a good feature as the liquid nails dries an off white. Another nice thing about these glues is they have no odor that I can detect. Make sure you run a putty knife on the bead of glue from the liquid nails as it’s too thick to spread itself.

6

fisherdm - What is a surform?
masonjar - can you think of the names of the spray adhesives?
MACKINACMAC - What do you mean by “a very long time to dry?” 2 days? 2 weeks? 2 months?

7

Good question. Stanley makes a few Surform tools including a shaver tool, a couple of files & a couple of planes called Surform. I suspect it is the plastic handled shaver that seems to be popular for working with foam. I’ll check it out tomorrow when I go get the foam for my new layout.

This is the link to Stanley’s Surform tools:

http://www.stanleytools.com

Click on products, then finishing tools then Surform tools.
(Tried to post the final URL but wouldn’t fit on one line.)

Wayne

8

3M makes a spray called 222 or 77 or something like that. Elmer’s (white glue) also makes a spray adhesive.

They generally can be put together in two ways - one is to spray one surface and slap 'em together while the glue is relatively wet. In some applications this makes a “temporary” bond sort of like a Post-it note, but stronger.

The other way is to use it like a contact cement - spray both surfaces, and then wait until they are relatively dry. Put them together for a permanent bond. Warning - you only get one shot at this, so make sure they are lined up!

Again - if you are going to usapproach, test the spray for foam-friendliness, and read the directions to determine how to make it bond the way you want.

If I can offer some info on the other questions too -

A surform is like a rasp or file - a little hand-held shaping device found at hardward stores in the handtools section.

The yellow glue we use at the modular club can take up to a week to dry in the foam-to-foam applications.

Andrew

9

I’ve built two of my own home layouts using foam, about a dozen Ntrak modules, and helped three friends build their home layouts using foam. Here’s my take on adhesives:

Use wood glue for all foam to foam, wood to foam, and general adhesive work. Wood glue works just fine to bond “stuff” to foam, it’s available by the gallon (and five gallon jugs too), and it’s a whole lot cheaper than any other adhesive in bulk. It’s also sandable and carveable. It’s pretty simple to remove if you need to as well (dry, you can just peel it off the foam surface).

Liquid nails/PL300: don’t bother. The bond is weak, the stuff’s expensive, and it actually melts part of the surface of the foam to achieve the bond (and yes, I’m talking about the foam safe stuff). It’s really hard to cut through, and almost impossible to carve or sand.

Spray adhesives: STAY AWAY!!!
This stuff is designed as a low tack sprayable rubber cement, and was specifically invented for magazine photo mounting use. The bond is TEMPORARY, and will fail on you in about a year. I thought it was the perfect adhesive for laying track until humidity swelled the wood in the layout, and I ended up with a Hotwheels track.

All adhesives but one (see below) have the same problem when used on foam: they take forever to dry. Foam isn’t porous, so there’s no air movement across the foam, and nowhere for the water in adhesives to evaporate to. Figure a week to three weeks for ANY adhesive to fully dry, depending on how humid it is. Fortunately, the bond is generally strong enough after 24-48 hours that you’ll be able to work the foam without it wiggling around much.

The only adhesive that doesn’t have this problem is foam-safe rubber cement (not the sprayable stuff!). Apply it per the instructions (add glue to one surface, apply the pieces together, remove the pieces, let sit for 10-45 minutes, and reapply) and you’ll have a dry, permanent bond in le

10

It sounds like wood glue (the yellow stuff) is the way to go from a cost effectiveness standpoint. Would I also use this to bond the cork roadbed to the foam? I was considering a hot glue gun to speed things up.

I plan to nail the track onto the cork until I can lock in the ballast and track with a diluted white glue mixture. Any comments?

11

You can use wood glue for everything, including gluing the track to the cork. I used wood glue on my track before I discovered the joys of caulk (from advice given on this list!)

And you’ll HAVE to use some sort of adhesive to lay the track. Nails won’t hold at ALL in foam, and the cork won’t give you a secure enough hold on the nails to keep the track from lifting and shifting. Besides, testing the heck out of your track well before you ballast is always a good idea. You should be fine with smearing a thin layer of wood glue onto the sanded cork surface (don’t glue down the switches!), laying the track onto the wood glue, and holding the track down overnight with push pins.

12

I used a little yellow wood glue on my layout but didn’t like because it dries too hard, like fisherdm said, and it’s hard to cut through with a hot wire. Although it is expensive, WS Foam Tack Glue is by far the best foam-to-foam adhesive I’ve found. Another idea you might want to try, if you are stacking flat pieces of foam, is carpet tape. It holds well and, of course, requires no time to dry. However, it’s also very hard to cut through with a blade or hot wire, so don’t apply it to areas you are going to want to shape later. I also laid track on carpet tape in my mini-staging yard, and it holds very well.

13

When you folks talk about “silicone caulk adhesive”, are you talking about the tub & tile stuff?

14

Yup. Use the clear stuff, and lay a small bead along the track centerline. Smear it around with a trowel (I also use it to fill in small gaps in the foam), slap down the track (making sure not to get any around switch moving parts!), and hold down the track with push pins. The stuff is great. It holds really well, gives you almost 45 minutes of working time to make fine adjustments, and is dry within 2 hours. It’s a nice, flexible glue bond, so it acts as a sound deadener. I use the cheapest stuff I can find.

15

FYI…

I sent an e-mail to Liquid Nails inquiring about using their product for gluing foam to foam. Below is their response;

Thank you for your e-mail.

No we do not have a Liquid Nails product that can be used to adhere
polystyrene foam panels to each other, the adhesive in the middle of the
panel will not be able to dry properly because the solvents will not be
able to evaporate.

It works for foam to plywood application because the plywood is porous.

If you have any other questions or concerns about a Liquid Nails product,
don’t hesitate to e-mail us back or talk to one of our customer service
representatives by calling 1-800-634-0015 option 4 Monday thru Friday
8:00am to 5:00pm EST.
Sincerely,

Michele
Customer Service

16

I’m still convinced that the liquid nails is the way to go. As far as dry time, it depends on the size of pieces your gluing. track & roadbed have strong bonds after about 1 or 2 hours, and Iv’e noticed the larger pieces take about a week to get a good bond but get stronger as time goes on. I was working a month ago on a dock scene where I had to cut about a 1’ x 1’ area from a 1" thick foam piece glued to a 2" thick piece to get at the water level. The lamination of sheets dried for about a month. Not that I waited that long, it just took this long to get back to the scene. The bond was so strong that I had to cut small pieces out of the area and actually pulled foam chunks out of the of the 2" lower foam sheet. Now I’ have to fill these holes (som as big as 3" x 3" x 1/2" deep). My wife and kids could hear the “POP” of the foam breaking off the glue upstairs. IT DOES NOT MELT ANY FOAM to bond. Ive’ also used it to build hills of foam 1" foam pieces about three or four layers thick. I started carving with a surform tool after about a week with good results. The only thing I noticed about the glue is that it has an elasticity to it that makes it stretch before it cuts. However this has not been a problem at all when carving the hills. I have built many layouts for myself & friends, (probably ten or so) and have used many techniques and like the Liquid nails the best. Ive’ used wood glue and its good but takes longer than the liquid nails to dry. I haven’t tried caulk yet. as far as price, I buy the liquid nails for about $2.19 a tube and so far on my 4’ x 12’ layout iv’e used about five tubes. But Iv’e glued just about everthing with it. A 1" sheet to a 2" sheet 4’ x 12’, roadbed, track, hills. A little goes a long way. My advice to you if your not sure. Buy a few glues and try each one to see what you like. Every one is different and has their own likes and dislikes. What I like probably will not be what you like , but who cares, It’s the end result we’re after not what methods you or any

17

Aleene’s Tacky Glue available in the crafts section at Wal-Mart and other places is very similar, if not identical to Woodland Scenics Tacky Glue at a fraction of the price.

18

Regardless of what glue I use (probably either Liquid Nails or yellow wood glue for the foam and caulk for the roadbed) my biggest challenge will be drying time.

My brother, an experience RR hobbiest, will be visiting me for 4 days to help me build my first real layout. Not being the types to do things the easy way, we designed an 8’ x 12’ U shape layout with about 150 feet of track. Our goal is to have trains running on three seperate loops before he leaves. We’re looking at some late nights.

Kind of like the show “Extreme Make Over” but for N Scale layout building.

Other than the benchwork and the first 2" of foam, everything else will be built as we go. As we construct cuts and fills, and lay roadbed and track, I need some assurances things won’t shift while the glue dries. There will be several areas with 2’x3’ sections of 1" foam and other areas with stacks of 1" layers.

I planed to use pins and weights to hold things in place. Any better ideas?

19

Thom,
Bamboo or wood skewers.
Bob
NMRA Life 0543

20

Thanks for everyone’s help.

Three days ago I began gluing down my foam. I tried both the liquid nail product and Elmer’s Wood Glue. They both worked fine. My preference however is with the wood glue because the edges dried quicker which helped to hold the lower sections of foam in place as I added height. I also liked that I didn’t have to use a putty knife to spread the wood glue.