Fastening foam to benchwork

[rrinker]

Well, all the benchwork is built, now it's time to fasten on the 2" foamboard tops. Everywhere I've seen, the preferred product seems to be Liquid Nails for Foamboards. I previously has 2 sections of 2x8' foam side by side with 4 crosspieces of wood to help maintain stability as a basic for my test oval. I used Liquid Nails and weighted the whole thing down with stacks of MR's (I have a pretty extensive collection of back issues) and left it sitting for 24 hours, then flipped the whole thing over and put it on top of a large table. When I went to take it all apart to make room to start building again, I found that the foam lifted clean off the wood with no effort, like it was never stuck fast. There is Liquid Nails strongly adhered to the foam (can't pick it off without gouging the foam), and there is Liquid Nails strongly adhered to the pieces of wood (ditto). So obviously is sticks to both materials, but seems to not stick to istself very well? What did I do wrong here, not leave it dry long enough? I am concernced here because those boards were some old pieces of shelving that I has, each board was 8" wide so there was a large contact surface. Now I will be trying to fasten a sheet of foam to a grid made from 1x4's, so the contact surface is only 3/4" wide around the perimeter with a crosspiece ever 16" on center. If not Liquid Nails, what shold I be using here?

--Randy

[Anonymous]

I fastened my foam using 1/2 screws (my foam is 1" thick) counter-sinking screws 1/8th inch into foam. screws are 1' apart in every direction. my cork roadbed is secured by liquid nails, which bonded very well.

[BR60103]

I used GREEN contact cement -- not the solvent stuff that dissolves foam. I think it's Lepages. Apply to both surfaces, wait until it goes dull, press together.

[Javern]

I use wood glue called Titebond II

[DonaldAgne]

You might try Woodland Scenics Foam Tack Glue. It sticks to almost anything and doesn't contract much as it dries. It's my favorite layout glue, although it's a little expensive. There might be something similar in the local hardware store that you could substitute. Maybe some of the other forum members have an idea. Also, silicone caulk sticks to foam and wood very well.

[orsonroy]

Since foam doesn't allow air to circulate through it, it takes several days for almost any adhesive to completely dry and form a good bond. Basically the only adhesive that's relatively fast is foam-safe rubber cement, but that gets expensive to use in the quantities needed for model railroad use.

I use plain old wood glue to glue foam to anything, weigh it down, and leave it alone for a couple of days. You can start carving the foam in 24 hours, but it's generally best to just work on something else for awhile. That's why I have several projects in process at once on my layout.

[rrinker]

QUOTE: Originally posted by orsonroy

Since foam doesn't allow air to circulate through it, it takes several days for almost any adhesive to completely dry and form a good bond. Basically the only adhesive that's relatively fast is foam-safe rubber cement, but that gets expensive to use in the quantities needed for model railroad use.

I use plain old wood glue to glue foam to anything, weigh it down, and leave it alone for a couple of days. You can start carving the foam in 24 hours, but it's generally best to just work on something else for awhile. That's why I have several projects in process at once on my layout.

Actually, shortly before I read this, discovered it by accident. I used some foam to make a backdrop, and where two pieces joined together, I reinforeced the joint with a scrap piece glued across the gap (on the back side, of course [:D]). I used tome plain old Elmer's Wood Glue. I went down to the basement this morning to check on it and it was stuck REAL solid, so I figured I'd try it for the flat tabletop as well. I glued about a foot in each direction from one corner and weighted it down with a couple of my plastic containers with magazines. About 2 hours later I went to check it out - it wouldn't move! It took a LOT of force to pu***he foam off the wood. The center was definitely not yet dry, but just the part around the edges that did already dry was holding with incredible power. So I applied glue tot he entre thing and put it back in place, brought over a bunch more magazines, and there it sits. By tomorrow this should be well attached.
Now I wonder if Homer D. Po will take back the 5 unopened tubes of Liquid Nails I bought.... I need more Elmer's and another light fixture.

--Randy

[robengland]

Liquid nails worked OK for me. I spread it THIN, and let it get quite tacky before pressing the foam down. As mentioned already, white PVA is good too.

[Anonymous]

I tried both Liquid Nails and Yellow (wood) glue. Both worked fine. I went with wood glue for the rest of the layout and saved quite a bit of money. As part of my testing phase, I noted how long it took the glue to dry. Under identical conditions, the wood glue dried in 8-9 days. The Liquid Nails product took more than 14 days.

[rrinker]

Wow, big difference! Well, the first piece was down with weight for about 36 hours, it is stuck on so tight that the only way it's coming off is to actually bust up the foam. So I glued down the second section and moved the weights (a chunk of my Model Railroader collection) to the new piece. Now it's off for some more glue so I can put down another section tomorrow. By the weekend, it should be ready to sand off the imperfections at the section joints. For a machine-made substance, the Owens-Corning foam isn't very uniform.

[bogp40]

Try using ceramic tile adhesive, came upon it by accident one time. I has very good initial tack, is cheap and water clean up. Apply or spread w/ a notched trowel the air gaps give suction and allow air for drying. Weighted down over night and its never coming apart.

Bob K.

[Anonymous]

QUOTE: Originally posted by rrinker

Well, all the benchwork is built, now it's time to fasten on the 2" foamboard tops. Everywhere I've seen, the preferred product seems to be Liquid Nails for Foamboards. I previously has 2 sections of 2x8' foam side by side with 4 crosspieces of wood to help maintain stability as a basic for my test oval. I used Liquid Nails and weighted the whole thing down with stacks of MR's (I have a pretty extensive collection of back issues) and left it sitting for 24 hours, then flipped the whole thing over and put it on top of a large table. When I went to take it all apart to make room to start building again, I found that the foam lifted clean off the wood with no effort, like it was never stuck fast. There is Liquid Nails strongly adhered to the foam (can't pick it off without gouging the foam), and there is Liquid Nails strongly adhered to the pieces of wood (ditto). So obviously is sticks to both materials, but seems to not stick to istself very well? What did I do wrong here, not leave it dry long enough? I am concernced here because those boards were some old pieces of shelving that I has, each board was 8" wide so there was a large contact surface. Now I will be trying to fasten a sheet of foam to a grid made from 1x4's, so the contact surface is only 3/4" wide around the perimeter with a crosspiece ever 16" on center. If not Liquid Nails, what shold I be using here?

--Randy

Latex Liquid Nails will be fine. However I have personally found 24 hrs to be to short a time span. I did the same basic thing you did with a mountain and a hill after 24 they came right off. I finally said the heck with it and left it for 3 days. Now to pull it off I'd have to break the foam

[Anonymous]

I used Liquid Nails Latex Adhesive For Foamboard & Projects, Product Number LN-604, to fasten foam down to an unpainted plywood base for a 6' x 9' layout about 2 years ago. I let it dry with weight on the surface for about 3 days and everything seemed to be good and tight. I then applied foam Track-Bed on top of the foam and laid flex-track on top of that. Everything worked fairly well for almost two years, but last Saturday I noticed that the foam board was separating from the plywood in a big way.
To heck with foam board. I'm going back to the old fashioned open grid with wooden sub-roadbed on wooden risers with screws and wood glue !!!

[rrinker]

I just glued on the last of 4 foam sheets tonight. I've been giving each one 36 hours under weight before goign onto the next one, using Elmer's yellow carpenter's glue to fasten the foam to the 1x4 grid benchwork. The ones that are dry, are NOT coming off unless I break it, I've tried. My test was to glue about a 1 foot long strip - well, I nearly broke the foam prying that off so I could get glue under the rest of it, and that was with less than 24 hours drying time. Like I said, the Liquid Nails is going back! By the weekend it will be time to lay cork. If I had any, but that's another story.

[darday]

In September 2001, I was building a 4x6' layout for my son. I wanted it to be light weight for portability, so I used 1/4" plywood on top of a small wood frame, and laminated 3/4" extruded styrofoam insulation on top of that for the scenic base. I used (latex) Liquid Nails for Projects to attach the foam to the plywood, placing a bead 1" in from the outside edge and then filling in the middle with beads spaced irregularly 2-4" apart. I weighted the foam down for about 48 hrs. and got what appeared to be a good bond.

However, though we have A/C plus a dehumidifier in the basement, by December the plywood had shrunk enough that there were areas of separation between the foam and the plywood. (Note: I had conditioned the plywood in the basement for nearly a year before construction.) There were about a half-dozen "pops" scattered around the 24 sq-ft. of table area, though overall, the foam remained firmly attached to the plywood. For areas of separation that were near the edge, I squirted in regular Elmer's glue and then added a 1" drywall screw, top down, using a homemade cardboard washer under the screw head to distribute the pressure over a larger area of foam and prevent the screw from pulling through the foam. For areas near the center that were popping, I just added the screw through a cardboard washer, since I couldn't get any glue underneath. The Elmer's has worked well, though one spot near an edge has become separated again.

If I had it to do over, I would probably use a wood glue or something that spreads more evenly than the Liquid Nails product, so as to provide a more even bond across the entire contact surface. I also would probably sacrifice some of the light weight objective and try 3/8" plywood.

[rrinker]

I don't expect much shrinkage, as we painted all exposed surfaces of the 1x4's, legs, and braces. The previous owners of the house left several cans of paint behind, included a gallon and a half of black (beats me what they painted black), so the benchwork was painted except on the top edge where the glue goes. Looks pretty good having all the legs and stuff black, makes it dissapear.

--Randy

[Anonymous]

Randy, actually, the rougher the surface, the more surface is available to hold the glue. The foam will hold to the glue much better than to the 1x's. One look at the foam and the wood will show you the difference in texture. I intend to rough my wood up to give it some more holding power. These glues are a mechanical bond, not chemical. I also remember seeing metal washers that are large, like a fender washer that have a countersunk center which might make the job even more secure, but I'll be darned if I can remember where I saw them. Bob T

[Anonymous]

fender washers can be found at any good hardware stoor and sometimes at auto stors. also stores like home depot and lows should have them

[Anonymous]

QUOTE: Originally posted by rt2907

Randy, actually, the rougher the surface, the more surface is available to hold the glue. The foam will hold to the glue much better than to the 1x's. One look at the foam and the wood will show you the difference in texture. I intend to rough my wood up to give it some more holding power. These glues are a mechanical bond, not chemical. I also remember seeing metal washers that are large, like a fender washer that have a countersunk center which might make the job even more secure, but I'll be darned if I can remember where I saw them. Bob T

[Anonymous]

QUOTE: Originally posted by rt2907

Randy, actually, the rougher the surface, the more surface is available to hold the glue. The foam will hold to the glue much better than to the 1x's. One look at the foam and the wood will show you the difference in texture. I intend to rough my wood up to give it some more holding power. These glues are a mechanical bond, not chemical. I also remember seeing metal washers that are large, like a fender washer that have a countersunk center which might make the job even more secure, but I'll be darned if I can remember where I saw them. Bob T

Washers like that are used to anchor flat roofing materials.

Dave W.