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What adhesive to join layers of the pink foam board?

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What adhesive to join layers of the pink foam board?
Posted by crossthedog on Monday, May 13, 2024 12:35 PM

I bought a 2x2 square of pink insulation board at Home Depot (I think it may be Homasote, not sure, but it's pink and it cuts with a utility knife), and I want to experiment with stacking four layers together, then carving their face to form a vertical rock wall.

Besides the DAP caulk, which I always use too little of at any one time to make it cost-effective (the rest of the tube hardens no matter what I do), what are my glue options? I have barge cement and Elmer's white glue. Either of those do the job? If not, what?

Thanks,

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

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Posted by BATMAN on Monday, May 13, 2024 6:54 PM

I have used low temp hot glue from a glue gun when in a hurry, but mostly use dap caulk. I like caulk because if the mountain gets bumped there is give in it and it doesn't get damaged. 

Whatever you use, keep the adhesive away from the edge you are carving as it can really put a damper on the carving when hitting glue. Figure out how much you are going to gouge out and add a cm or two as a margin.

 

Brent

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Posted by cowman on Monday, May 13, 2024 7:13 PM

How thick is your board?  Never heard of 2x2, but then most of my foam has come from construction sights.

I use inexpensive laytex caulk for foam to foam, foam to wood, foam to cork, track to cork.  I do not put adhesive under turnouts.

What I do to keep my caulk from hardening is to put a screw big enough to be screwed in, not pushed in the tip, then wrap the tip in several layers of cling wrap and secure it with a rubber band.  I've had some stored over 6 months still useable.

Good luck,

Richard

 

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Posted by crossthedog on Monday, May 13, 2024 7:27 PM

BATMAN
Figure out how much you are going to gouge out and add a cm or two as a margin.

Great tip, Brent, thanks for that. I would not have considered that. Your second photo is very instructive because I can see that you even used a peice of what looks like the same material I'm using standing on its edge. The area I want to carve is a sheer drop (which is why I want it to be rock, not a greensward) and there is very little room for the material, horizontal depthwise. I'm now thinking that I might consider mounting a piece of the foam standing upright.
cowman
How thick is your board? Never heard of 2x2... What I do to keep my caulk from hardening is to put a screw big enough to be screwed in, not pushed in the tip, then wrap the tip in several layers of cling wrap and secure it with a rubber band. I've had some stored over 6 months still useable.
Board is 1 inch thick. I have also used a similar method to try to keep the DAP from hardening, but I may use only one or two squirts once and then not need any again for a year, I work so slow. That's why I was hoping to stay away from the caulk gun.

I've bought two tubes. The first one I bought I put a fat nail in and wrapped it with tape, which worked fine when I used it again 3 months later, but 6 months after that it was so hard in the tip that when I forced it using the trigger/ratchet mechanism the back of the tube exploded and I had DAP all over myself and the gun and everything.

 

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Posted by kasskaboose on Monday, May 13, 2024 7:47 PM

I use liquid nails to secure layers.  Whatever you use, put a long screw or unfolded paper clip to prevent the tube from drying out.  This is speaking from experience of letting the tube dry out (yes, I covered it too).

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Posted by BATMAN on Monday, May 13, 2024 7:47 PM

crossthedog
there is very little room for the material, horizontal depthwise. I'm now thinking that I might consider mounting a piece of the foam standing upright.

I had a couple of spots where I had very little space to put a rock face. What I did was carve out the foam on the flat side to look like a rock face and then slice it off like a piece of bread to about 10cm thick and glued it in place.

Brent

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Posted by MidlandMike on Monday, May 13, 2024 8:16 PM

Whatever you use, make sure it is foamboard-compatible.  Some caulks/adheasives will chemically react with foam.

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Posted by NScale4x8 on Monday, May 13, 2024 8:39 PM

I use ordinary yellow wood glue.

You can score the foam to give the glue more grip. I've tried it with and without scoring and have not noticed any difference.

Spread the glue thin and even. Leave glue exposed to air for at least ten minutes. Press the parts together. Adjust. Pile weights on top until glue is dry which may take two days if it is a large surface with no air contact.

Do not use glue that expands like traditional Gorila Glue.

Do not use products like liquid nails or sillicone caulk on foam. They may either dissolve the foam or be catalyzed by the foam into drying too quickly and unevenly.

Be sure to remove any plastic vapor barriers on the foam. The glue will stick to the barrier just fine, but then the foam will separate from the barrier.

https://nscale4by8.github.io/nscale4x8/

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Posted by tstage on Tuesday, May 14, 2024 7:19 AM

DAP Alex Plus Acrylic Latex Caulk with Silicone

It holds very well, dries flexible, and is only $4 for a large tube.  I've used it on foam-to-foam, foam-to-cork, cork-to-cork, and cork-to-work.  It also doesn't contain any nasty chemicals so it's safe to use indoors.

Tom

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Posted by crossthedog on Tuesday, May 14, 2024 7:55 PM

Guys, thanks again for the follow ups.

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

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Posted by maxman on Tuesday, May 14, 2024 11:13 PM

Homasote is not pink.  It is a gray color.

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Posted by FRRYKid on Wednesday, May 15, 2024 2:58 AM

NScale4x8

Do not use products like liquid nails or sillicone caulk on foam. They may either dissolve the foam or be catalyzed by the foam into drying too quickly and unevenly.

That's interesting. I use Liquid Nails (exterior grade) all the time for my bead board and I've never had a problem with it. As already mentioned, make sure it's foam board compatible.

As to the hardening problem, Liquid Nails and such say on the tube that it should be used within a year of opening. For keeping it fresh, I have used caps specifically designed for that purpose and I have also put a piece of Duck Tape to seal the nozzle as well. All seem to work to keep everything fresh.

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Posted by rrebell on Wednesday, May 15, 2024 6:47 AM

crossthedog

 

 
BATMAN
Figure out how much you are going to gouge out and add a cm or two as a margin.

 

Great tip, Brent, thanks for that. I would not have considered that. Your second photo is very instructive because I can see that you even used a peice of what looks like the same material I'm using standing on its edge. The area I want to carve is a sheer drop (which is why I want it to be rock, not a greensward) and there is very little room for the material, horizontal depthwise. I'm now thinking that I might consider mounting a piece of the foam standing upright.

 
cowman
How thick is your board? Never heard of 2x2... What I do to keep my caulk from hardening is to put a screw big enough to be screwed in, not pushed in the tip, then wrap the tip in several layers of cling wrap and secure it with a rubber band. I've had some stored over 6 months still useable.

Board is 1 inch thick. I have also used a similar method to try to keep the DAP from hardening, but I may use only one or two squirts once and then not need any again for a year, I work so slow. That's why I was hoping to stay away from the caulk gun.

 

I've bought two tubes. The first one I bought I put a fat nail in and wrapped it with tape, which worked fine when I used it again 3 months later, but 6 months after that it was so hard in the tip that when I forced it using the trigger/ratchet mechanism the back of the tube exploded and I had DAP all over myself and the gun and everything.

 

 

Sometimes you have to dig out the caulk but first which Dap caulk do you use, their are many and alot have different properties. What you wand is white acylic caulk that is silonconized, about $3 a tube at Walmart. Just forming an end cap of caulk is good enough of a seal for a year.

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Posted by Professor_Train on Wednesday, May 15, 2024 6:07 PM

How well does the Dap caulk respond to using hot wire to carve the foam?

 

chuck

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Posted by hon30critter on Friday, May 17, 2024 9:42 PM

crossthedog
I bought a 2x2 square of pink insulation board at Home Depot (I think it may be Homasote, not sure, but it's pink and it cuts with a utility knife)

Hi Matt,

I think what you bought is not Homasote. Homasote is light brown with a fiberous surface and core. You bought pink foam insulation which is exactly what you want for what you are doing. Some people still use Homasote as sub-roadbed because it holds track nails well, but cutting it can generate a lot of fine sawdust which can make a real mess.

Cheers!!

Dave

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Posted by maxman on Friday, May 17, 2024 10:49 PM

Humm.  Thought I said that about 4 posts above.  And the stuff the local Home Despot sells is a grey color.  Sometimes they call it sound board.

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Posted by azrail on Thursday, June 13, 2024 3:53 PM

Styrofoam brand foam board (now made by Dupont) is now gray colored.

Also Power-Loc adhesive is a good choice for gluing foam and works quicker.

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Posted by crossthedog on Saturday, June 15, 2024 9:53 AM

You all are correct. What I have is not Homasote, it's the Owen's Corning pink foam (extruded polystyrene, I think). My Home Depot sells it either in 4'x8' sheets that are 2" thick and cost more than 50 clams a sheet or else in 2'x2' sheets that are only 1" thick and cost less than a sawbuck each. I went with the small square because I just wanted to try foam out as a scenery base. I would rather have the thicker but I have neither the financial leverage nor the storage to be buying $56 sheets of foam just for experimentation.

The "caulk" I used turned out to be one of the Alex adhesive products. I don't know which one offhand and I have "cat-lap" right now so I am unable to go and look. It worked well.

 

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Posted by crossthedog on Saturday, June 15, 2024 10:01 AM

The DAP product I used -- both tubes -- turns out to be the Alex Plus that Tom shows above. This time I have put a long nail in the top and wrapped it very well. Also, now that I have started doing scenery, it's likely I will use more of it more often, so I may not have to waste the rest of this tube.

Thanks again, guys.

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

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Posted by BATMAN on Saturday, June 15, 2024 10:06 AM

I have been using these tube covers for caulk and other things for years. They are cheap and work great.

 

Brent

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Posted by MisterBeasley on Saturday, June 15, 2024 3:41 PM

I don’t do carving of the sides of my foam rocks.  I will stack them to get more elevation and then coat them with a Gypsolite slurry and other scenic material, including plaster cloth, depending on the effect I want.  Because once it's glued down it has no mechanical stresses, I find that white glue works well enough.  I do give it several days to harden because the foam sheets seal together tightly and it takes a while for the glue to get enough air to dry.

I have a lot of hydrocal castings I use for vertical cliffs, and I really like Bragdon Foam castings for up-front scenes I want to highlight.

It takes an iron man to play with a toy iron horse. 

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Posted by crossthedog on Saturday, June 15, 2024 7:21 PM

@Brent, where did you get those? They look like corn-on-the-cob holders. I bet they work well.

@Beas, do you have any photos of some of those Bragdon castings? I tried a few castings but I haven't found a method that works for me yet.

 

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Posted by Capt. Grimek on Sunday, June 23, 2024 12:14 PM

The Bragdon castings (and his method) are fantastic. I chose them because I was building a layout that required me to work alone and climb up on the benchwork and his method/products allowed me to put up 2'X2' castings that weighed only a few ounces!  

The molds themselves are high quality latex like Hollywood uses for masks, etc. and Bragdon was a geologist so his molds are very realistic and regionally specific (granite, sandstone, whatever).

I don't have photo sharing abilities here but there should be examples online. I personally think they're the most realistic molds around.

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Posted by hardcoalcase on Wednesday, June 26, 2024 11:04 PM

crossthedog

Besides the DAP caulk, which I always use too little of at any one time to make it cost-effective (the rest of the tube hardens no matter what I do), what are my glue options?    -Matt  

[quote user="crossthedog"]

I've found that as long as I don't leave an "air hole" in the tip of the nozzle, the caulk tube will remain useable for a seemingly endless period of time.  When done with the project-at-hand, I'll give the caulk gun handle a few light pumps, until the caulk in the nozzle doesn't get sucked back into the tube.  At the end, I'll use my finger to smear the last blob of caulk across the nozzle tip, making an air-tight seal.  When the caulk is needed again, some forceful pulls on the trigger will push the hardened blob out.  If not, cut a small amount off the nozzle (1/4") and try again.

Jim 

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Posted by rrebell on Thursday, June 27, 2024 7:58 AM

I used to leave a small lump of caulk on the end after doing my work, pull that off and it was still good six months later, after about a year you would have to dig it out some or cut off more of the tip. I always use the stuff pictured, used to use by the case in the old days.

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Posted by BATMAN on Thursday, June 27, 2024 10:45 AM

crossthedog

@Brent, where did you get those? They look like corn-on-the-cob holders. I bet they work well.

They are available at most big box stores for a couple of bucks

Caulk Cap Caulk Saving Cap Caulk Sealer Saver Open Caulking Tube for Sealing  And - Walmart.ca

These were $1.98@ HD.

 

Brent

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Posted by richhotrain on Thursday, June 27, 2024 4:34 PM

To seal a partially used tube of caulk, I stick a 16 penny nail into the tip of the caulk tube all the way down to the head of the nail. Then, I twist a small piece of Saran Wrap around the tip of the caulk tube and secure it with a rubber band. The remaining caulk will remain usable forever.

Rich

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