Hello, In the process of making a few hills and a larger mountain from pink 2" foam board and need advice on what glue to use. I'm stacking the foam in layers and have tried a tube of the PL300 foam board adhesive but found it is just way to thick and I can't get the pieces to fit tightly on top of each other even when I spread the adhesive out to a thin layer. Any suggestions on a thinner type of glue that would work? Thank you!
I use plain old Elmer's White Glue spread thin. Not necessary but for larger pieces I spread with a notched piece of plastic or cardboard used as a glue trowel works good. Spreading with the notches leaves strips without glue and gives the glue more surface exposure to air, even though it is sandwiched between layers. Just like gluing down floor tile. I hold pieces in place with weights or pin it down with long tee pins or finish nails.. Down side is it takes overnight to dry.
I've used both Elmar's Glue and DAP caulk with good results. My preference between the two was the DAP.
Liquid Nails latex indoor adhesive holds well. I am not sure about the thickness though. Perhaps test some.
I have had good success with Liquid Nails for larger pieces (and use a piece of stiff cardboard or disposable spatula to spread), DAP caulk for smaller pieces.
For smaller hills and such I use a slightly different method. While building hills I use 'bamboo skeweres' for holding the pieces in place till I have what I want. Then I spread Elmers with a long skewer and / or I ease the each skewer out apply Elmers to the skewer and down the hole. I use rocks for weights. In general I use 4" and 6" skewers.
I used No More Nails (Liquid Nails competitor). Sets fast and it's tough. A good portion of my layout holds together with that stuff. Foam base to MDF boards, foam hills to foam base, grass rolls to foam base, tracks to foam base... etc.
I stopped at the store on the way home to pick up some white glue which was my first choice and was quite shock at the price of just basic Elmers white glue. So proceed to the hardware store and picked up some Dap latex caulking instead which was way cheaper than white glue. When did white glue become so expensive mind you I live in Canada where we pay way to much for everything here.
I like the long shelf life of white glue and the fact ballast and ground cover glued down with white glue can be removed by soaking with alcohol and scrapping.
Notched trowels/spreaders are designed to ensure the correct amount of mortar or adhesive is applied per unit of area for wall and floor covering materials. The applied volume of mortar/adhesive will level out to the correct film thickness if the size of the notch specified in the mortar/adhesive instructions is used. When no such instructions are provided, the choice of notch size may be experimental. Then angle between the notched applicator and surface also affects the volume applied, and therefore the film thickness between bonded materials. In closed areas (e.g. between foam sheets or floor covering and floor, etc.) there is relatively little air exposure, so moisture is slow to evaporate, but may be absorbed by the material(s) being bonded. Foam safe adhesives, usually applied from caulk tubes/guns, are designed to cure without needing much air exposure, but are often more permanent than we modelers might prefer. White/yellow glues will work, but are much slower to cure between closed cell foam sheets (most foam insulation boards). Some (usually thin) sheets of foam insulation board come with a plastic film on one or both sides to increase the material strength when handling/moving the material. This film should be removed (simply peeled off) before installation if glue/adhesive is used.
I've been using Loctite PL375. It's what I had, and seems to work fine. I use weights and pins and such to hold the pieces together, and wait 12 hours.
Has anyone tried tile cement , the kind used to glue down floor tiles or linoleum flooring . I installed a floor a while back and got some left over . I might give it a try when the time comes.
Hmmmm.... I guess I am a bit weird in my technique. I use a hot glue gun, and on the high setting at that, with the extruded foam insulation (pink, blue, green, whatever color the big-box hardware has). Yes the glue does melt the foam a bit, but that is a feature as the solidified glue blob will ooze down into the foam a little bit. I cut each piece of foam to the desired shape with a hot wire cutter, quickly put blobs of glue 6 or 8 inches apart on the lower piece, put the next layer on top, squeeze it down and slide it a bit into position if necessary, and it's done. Glue solidifies in a few seconds and it's on to the next piece without waiting.