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Discussion Starter · #1 ·
I am to finish building a yard on the club layout using a construction method unfamiliar to me. The yard area is 1/2" plywood with an (as yet unfastened) 1" blue foam layer over it. I need to go to Home Depot or Loews to get the stuff to finish it. A few questions:

1) Readily available adhesive to glue the foam to the plywood?

2) Filler to use in the cracks where pieces of foam join (up to 1/4" gap)?

3) Paint for the foam surface to seal it and provide base for fastening track?

4) Adhesive to use with Atlas Flex-track?

The yard is in a separate room from the main layout and will be used as storage for complete trains, i.e. not a staging yard (although that could change, as all modellers know ...). There is background on the wall behind the yard, but scenicing the yard is not planned.

Thanks for your help!
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Super-C
Tucson, Arizona
cell (505)228-3137
 

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PL300 is a good bet for foam to foam or plywood. It's what I have used for 15 years, but some other members will possibly have other suggestions. Some swear by white glue, but I would be hesitant. Come to think of it, though, Aleene's Tacky Glue might work. Find it at Wally's crafts.

Filler should be anywhere from spackle to drywall mud, or sculptamold (Walthers), or mix sawdust with white/yellow glue to form a putty and shove that in between. My choice is spackle.

You don't need to seal/paint/prime the foam. It takes paints and glues readily any time you wish to apply it. Personally, DAP Alex Plus 'clear' does a good job adhering track elements to just 'bout any surface you're likely to put it on. If you are unfamiliar with it, it squeezes out of a glue gun white (don't panic!), but it dries slightly yellow and clear.
 

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I would think many glues would work. I glued foam together with gorilla glue. It expands a little. It makes a hard seam though between the pieces. It fastens well but it can be possible to pop the pieces apart with a little luck and lot of muscle. I've done it. But you want foam to plywood. I'd be very tempted to try something else. Maybe a white glue or carpenters glue before getting into gorilla or even more industrial strength stuff. It's just easier to work with. Maybe someone else has some thoughts on it.

Gap or filler. I've tried vinyl based spackle which might be ok. It can take awhile to dry if it's thick. Grout or faster drying drywall mud might work.

Paint. I used acrylic based hobby paint. (Not Vallejo, check the craft section of for example hobby lobby) Some green to sandy or light brown colors. Not sure about latex paint. With the paint wet I sprinkled the ground cover I wanted on that as a first coat. Worked ok.

Track to foam. I'd go with some kind of caulk. In fact I did track to cork to foam mostly with caulk. However the is probably not necessary. I had the cork from another effort. Anyway I used a gray window caulk. Dap brand. But there's a lot of caulk out there I didn't want a silicone based one. Too shiny and unsure paint or gravel would stick. Anyway squirt a bead, spread it thinly as needed. Put the track section down on it. Clean up excess if any or adjust. Take care in regard to switches... They have to swing. Weight it down to dry with soup cans for example.

That's my take.
 

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i used alex plus, for adhering foam to base plywood, and track to foam... it's lasted a half dozen years sofar ... takes 12 - 24 hours to cure, should be held down during the cure time ..
minor gaps can easily filled with ground foam, nothing else required
and one other major advantage, cost is only 3 bucks for a 10 ounce big tube!
 

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1. Liquid nails for projects
2. Liquid nails for projects.
3. Don't need to seal it. You can glue the roadbed or track directly to the foam. If you just want to cover the blue foam get a latex primer like Kilz and have them tint it dirt color.
4. Liquid nails for projects.
 

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Considering that wooden benchwork and any sub-sub roadbed plywood will expand and contract if climate is not perfect, I see no reason to attach foam to ply wood beyond slightly counter sinking a few trim head screws thoughtfully applied here and there around the area.
Think as, one surface bound to move more than the other. Allow surface 'slippage' between the two.
That said:
I like the idea of just using which ever loose ground cover in the foam to foam seams idea. Especially since I would, and have glued foam to foam sections together, which would fill most of the gap to begin with.
Tinted Kilz primer. Hmm, now there's a great idea! Ive been hip to that product for decades. Never thought to use it as a tinted base on scenery. (not that Im big on scenery anyway-lol).
 

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Considering that wooden benchwork and any sub-sub roadbed plywood will expand and contract if climate is not perfect, I see no reason to attach foam to ply wood beyond slightly counter sinking a few trim head screws thoughtfully applied here and there around the area.
This is not necessary. Plywood is pretty dimensionally stable, and using PL300, Liquid Nails for Projects (make sure it's the "for projects" variety, the basic stuff attacks foam) or latex caulk provide enough flexibility when cured to handle it. Sealing the raw wood also helps. Since this is an expansion of a club layout, and they specified this technique, they can be assumed to have used it elsewhere without issues. Apply your adhesive in an S pattern so that it can cure, because the foam doesn't breathe.

As far as the rest of the comments, I think the rest of the advice is pretty good: fill with whatever works (I use drywall mud or foam putty), although Sculptamold (not a Walthers product, but made by AMACO -- THE American Art Clay Company), while great for terrain modeling, might be a little heavy to fill gaps with.

Good luck!
 

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Foam-to-plywood: Liquid Nails for projects, get the caulk tube quantity. Also buy a few cheap plastic putty knives. I got a set at Home Despot of three knives for like $2.

One piece of foam I laid did not adhere over the beads from the caulk gun. Had to rip- it up. Second time I used the plastic putty knife to spread the LNforP and much happier with results. Easy to clean the knives with warm water and a bit of scrubbing. If you have a few flats of water bottle from Costco or someplace like that, they make great weights while the LNfP cures.

I used the spackle stuff that I had on hand for filling in wallboard nail holes. Worked just fine!

No roadbed? I'm using Woodland scenics foam roadbed (sheet form) for my yard and have bought their tacky foam glue, or some-such name. For track to the foam roadbed, I have heard LATEX caulk does just fine. Using a gray colour will blend with ballast.
 

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I forgot sculptamold as a possible filler -- I have a box of it and have now used it and like it. So that's an option as mentioned above as well.
 

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I use wood glue for foam to foam and foam to wood. Works great.

Fire track to foam in using a low temp hot glue. Heavy duty glue guns will melt the foam, but the low temp will not. I'm using unitrack, so that's a little different, might be harder to hide the glue with flex or sectional.

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I used just standard white silicone to glue my foam to the plywood. I used it to glue the road bed down as well. And with track I have used school glue because once I have all the ballast glued down and laid then it gets pretty stout and I think it’s more or less personal opinion. They all seem to work well
 
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