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After complaining repeatedly about not being able to find extruded foam in California, I finally found some. It's the blue variety. So now I'm working with this stuff for almost the first time. (Iwas able to get a few scraps earlier.) I have some questions for seasoned extruded foam users.

1) What do you use to glue slabs of foam together in order to form hills? I tried white glue, which holds the two pieces together well enough, but I don't think it will dry anywhere but the edges. The center won't get enough air to dry out and set up. I also tried a hot glue gun. This works, but it tends to melt into the foam. That's not a deal-breaker, since it does set up quickly and holds well. In the past, I've used double-sided tape. That grabs instantly, and forever, which makes it unforgiving if you don't have the pieces lined up exactly. It's also expensive, and the tape can get in the way when you shape your hill.

2) What do you use to bond foam to wood, or plastic? Will the same adhesive used to bond foam to foam, also work with wood or plastic?

All suggestions welcome, thanks in advance;

Traction Fan 馃檪
 

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I used mod podge to glue sheets together. Make sure you remove the plastic film from it. I don't know if it dried all the way in, but I do know it's a good solid bond.

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I've always used liquid nails construction adhesive. Some states foam specific but I've never had any that wouldn't hold.
 

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Sometimes I use hot melt glue (on the low heat setting). Sometimes I use Loctite Powergrab. Sometimes I use them both at once. The hot melt glue give an almost instant bond and the Powergrab makes sure it's permanent.
 

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I have always used Liquid Nails construction adhesive. It is compatible with the foam whether it is blue, pink or green. I just run a bead all over one piece and spread with a wide putty knife. Kind of like spreading drywall filler. Then I will weight it with several train magazines or adjustable bar clamps and wood strips for 24 hours. Just depends upon how big a piece I'm gluing.

Kenny
 

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Try Liquid Nails "For projects" its for foam, while regular Liquid Nails is not. Note that if you make a ring around the foam, them put some dabs in the middle, they may not dry, a star pattern might be better.
 

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I use LePage's PL300 (variety safe for use on extruded foams). I have read many times that people can use almost anything and find that it works. Just not something that will 'melt' or soften the foam itself, so I think the DAP-with- silicone caulks are a no-go. But straight cheapo acrylic caulking would work, and a little goes a long way if you force the two slabs tight to each other by placing scraps of board/plywood atop them with weights, paint tins, soup cans, driver batteries...

BTW, when I go to erect tunnel portals by standing them in place on the plywood roadbed, I use a dab of PL300 under their two feet. PL300 isn't quick to cure, but it does stiffen inside of about 24 hours if you haven't placed half an ounce per dollop. As in all applications of adhesive, it is easy to use far more than enough.
 

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What I use to bond foam to foam is not really an adhesive per se, but a paint. It is PPG's Gripper Primer paint. It used to be made by Glidden, but PPG bought out Glidden. You can get it at Home Depot. I paid about $26 for a gallon. That sound expensive, but it will glue a LOT of foam, and the cost of Liquid Nails for projects to do the same amount of foam would be astronomical! You can also buy it by the quart for about $12.
Of course, it also depends on how much foam you have to glue. If you only have 1 sheet of foam to glue, the Liquid Nails might be the way to go.
I paint one side of the foam, put the other piece on and weight it down. After 24 hours you will not get the two pieces apart without destroying the foam. It also works well to glue foam to wood and Homasote. It's good stuff, Maynard!
 

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Well, you're right -- any water or solvent based glue won't ever cure in the middle if you surround it with other glue. Use an S shaped bead to allow curing.

A few dabs of Liquid Nails holds my foam to the benchwork, and I use hot melt glue for foam to foam bonds (as well as attaching servos for turnout control).
 

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Can't you simply open one of your own preset push-button 'how to's' that you always post, and simply go by that ? You mean it Isn't it in your roster; 'How to glue foam pieces', or titled 'Types of glues for types of materials ? I find it hard to believe you wouldn't have this particular instruction, what with the abundance of gluing done in MRRing..
 

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Discussion Starter #12
Can't you simply open one of your own preset push-button 'how to's' that you always post, and simply go by that ? You mean it Isn't it in your roster; 'How to glue foam pieces', or titled 'Types of glues for types of materials ? I find it hard to believe you wouldn't have this particular instruction, what with the abundance of gluing done in MRRing..
Cute!

Traction Fan
 

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about the only difference between the blue, green and pink extruded foams, is that the colour designates the manufacturer .. that's all ... and yes, you can mix them ..
 

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The pink that I have is much denser and heavier than the green. Probably 3x.
Then they're not the same product. The green that you have is likely florists foam (which is also an extruded foam product, and also makes good terrain), not insulating foam. I have used all three colors of insulating boards, and they're very similar, almost jndistinguishable (except by color, of course).
 

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Those are the common products, yes. I have used both, and there is no noticeable difference in the stuff I get.
 

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i have used foam quite a bit in my layout, the foam is bonded with pl300 to the flat laid 3/8 plywood ... at different points i have up to nine inches of foam stacked up, the track is glued to the foam with dap alex caulk ..
the layout size is about 16 feet by 15 feet, and depicts an up north logging / mining area in era 1890..
also attaching some photos of the layout, been up for seven years now .. the photos are somewhat misleading, as the foam is only under where the track is laid, other places are covered in dap soaked heavy duty paper towels only, and are hollow underneath
 

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Here鈥檚 another example. I made a mountain with pink rigid foam. I made it in pieces so it could be removed in case of a derailment. Most of it was covered with Structolite, Mold-A-Scene or Sculptamold. Some was just shaped and covered with turf.

BTW, if you are just going to cover it with turf or paint, you can use Woodland Scenics Foam Putty to hide the seams.

547318

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