What kind of glue?

I’m at least going to hose it off. I don’t want to tuch it, let alone cut it to shape.

If I remember correctly, what he was being advised to do was to lay the diluted glue thick on the surface to get good spread coverage and void filling, then let it largely dry as if it were contact cement. That if it works would greatly reduce his drying time…

I’d argue that if you’re flooding the surface of dirty foam, you’re making the dirt particles into the equivalent of aggregate in a composite, and losing little if any actual joint strength if the glue penetrates ‘under’ the dirt. I’d be tempted to have him brush the dirty surface after applying the glue to ensure penetration to the actual foam-plastic face.

Except white glue won’t work like contact cement. Once it dries, it’s dry. ANd not so sticky any more.

Now, there ARE foam-safe contact cements that won’t eat into EPS foam. That’s another option. But it does require careful placement since you get exactly one shot at it. I probably could ahve done that since the way I built the framing for my old layout, I used 1x4 rails with 1x3 crossmembers so the foam sat down slightly inside the frame rails, which would have lined it up nicely for that one shot at getting it stuck in the right position. But I also still had my entire collection of old MRs at the time, so plenty of things to lay on top of the foam to weight it down and, since I am slow, waiting until the next weekend to use the section I built wasn’t a big deal. But I did literally lay stacks of magazines evenly covering the ENTIRE surface of the foam to weight it down, not jsut, say, the corners and the center.

I think if I were doing it again, laminating foam to foam for benchwork purposes, I’d go for the contact cement. FOr stacking foam for scenery purposes, I’m thinking hot glue is perfectly fine. Especially after the scenery demo clinic I saw. Although once again, the guy made it look so super simple, which it never is for me. But he’s an artist and costume maker (cosplay, halloween, scifi type things - neat stuff) and I most definitely am not. But like I need those artist types to do my scenery, those artist types need me to do their wiring, so we’re even. [(-D]

–Randy

When did anyone say anything about fully drying? The methods I was reading say you let it go to the point it’s become very viscous but is still tacky. (And truth to tell, that’s the way I use solvent contact cements, too; I see them as decidedly not the same thing as using rubber cement for pasteup!)

In theory, at least some of these glues soften when wet, and this might make enough interfacial activity to give you a renewed bond. I have also read (although I can’t remember where) that heating a glue layer once it is ‘dry’ can bring up its surface activity for good renewed bonding; doesn’t Walthers Goo have this property?

Something that is tickling my thinking, derived from veneering: would it be better to prepare the joint between foam and benchwork by applying some filling material to the foam that can be dutched to a good contact surface, and a corresponding filler to the benchwork wood, and then make the actual interfacial adhesive joint using a material between those two prepared “flat” surfaces? I know it’s more steps, but at times the better result is worth it.

This dancing around solutions is becoming tedious: there are foam-compatible adhesives readily available that will affix foam to wood, concrete, other foam, the bottom of your shoes or the back of your head - get some!

LePage PL 300 adhesive for foam board is one brand, and I’m sure that there are others available. Follow the instructions on the tube.

If you hose-off the dirt and let the foam dry, it should be ready-to-use.

Wayne

I’ve had bad luck with those types of adhesives - I originally was going to biuld a test 4x8 by attaching two pieces of foam (around here, we used to only get the pink stuff in 2x8 sheets - Lowe’s now has 4x8 sheets of the green version) with some wood. Based on all the recommendations of the use for the Liquid Nails for Project (foam safe) product, I used this to adhere the foam to some wood to link it all together,. Weighted it down and left it for a week. A week later, I picked it up - and the foam popped right off! THe adhesive was dried, hard as a rock.

I also used some of the regular liquid nails to glue on a toilet paper roll holder after redoing the bathroom. You know, what the stuff is supposed to be used for - ceramic to ceramic. Never did get it to stay on. Just one of those product brands I’ve had nothign but bad experiences with and will never ever buy again. Some of the work on my basement remodeling, the contractor used some other brand of construction adhesive to attach wood to the cemenet - trying to pry that off, the wood will shatter before the adhesive lets go. For anything needing a construction adhesive - I will use that brand.

–Randy

Woodland scenic foam tack glue is white glue (PVA) and works well as both regular adhesive like a wood glue and as a contact cement if you follow those directions. PVA glues foam. Foam tack just glues foam better because it has something added. Ordinary white glue (PVA) is definitely NOT waterproof and water will dissolve cured adhesive. Yellow glue is generally waterproof nowadays. There are roof white glues but why anyone would use them for a train table is beyond me. If you insist on wooden benchwork then stick to carpenters yellow glue it’s perfect for purpose. White glue works for just about anything else you might need by way of layout foundation work. I use low strength acrylic caulk for trackwork in case I want to move it. Or I use track nails unless into foam.

Construction adhesives are not very strong generally for some good reasons.

Reference to laminating veneers (or Formica type products) is relevant. The end result desired is very similar. The main differences are foam and plywood aren’t going to develop air bubble distortions and a continuous adhesive film is totally unnecessary.

In fact, a perimeter bead with a few dots here and there inside the perimeter is going hold that foam no problem.

Of course if you delete the wood entirely you solve all your problems in one go.

One of these days railroad modellers are going to stop thinking they need benchwork strong enough to stand on. You just don’t if you design your layout so you never have to put your weight on it. That is not difficult. Design for a 24" maximum reach and you’re done. Use just foam.

[ Rant ] I effectively have four levels connected by a 2.25 percent grade. Sure I could have built it with foam, but it would be a lot more time consuming.

I just cookie-cut them and set them up for a 3% grade. Turns out I thought 3% looked off. So, I took out the the veritcal supports and 2 1/2 hours later, I had a 2.25% grade.

I’m probably going to use a lot of foam. I may use carboard and plaster cloth, too.

I used to pound nails for a living. I’m very comfortable with wood. But I understand that there are plenty of people out there that would benefit from forgetting the plywood and using the foam directly on the frame. These people would be building a mostly flat layout.

My layout is mostly a mountain, with a town at the base. Tunnels are open from the sides. Up the mountain are a silver mine and a logging camp. Making everything out of foam for me would be a project.

[ /Rant ]

And the debate continues.

It’s pretty much a moot point now anyway. I glued it down with straight white glue, screwed it down with drywall screws–relax. Just for shear forces–and I have my wife’s panty weighting it down. I gave the whole family a tour so they could see where their food was if they decided to make something.

Thanks everyone. It’s been an education.

[-)][%-)][-)]

I’ve said it before and I’ll say it again. It was quite an effort to change stuff glued with Poly-Seam-Seal.

If you want something permanent with any kind of foam, it’s 2 in 1 Poly-Seam-Seal. The stuff is like Super Elastic Bubble Plastic!

If you want to be able to change something someday, it’s Alex plus, which is easily reversible. Done here many of times.

BUT

If you want to eventually carve two pieces of adjoining foam and don’t want any problems doing so and never want to see the seam, … Great Stuff Window and Door foam. A little messy at first but you learn to get the hang of it real quick!

Less is More

PS Don’t ever try to wipe away the excess of expansion foam. The results are not good and you don’t want to do that. Just leave it for later and it will be fine

TF