Gaps between foam boards

[topcopdoc]

I have finished laying my track. I also laid the various pieces of 1inch Pink foam board to put my structures on. The foam does not fit together exactly. I would like to seal the cracks between the foam boards. I need a good level seal because roadways and other scenery will be placed upon it. I have heard that glue might not hold or may leave little valleys when it dries. I was planning on using clear packing tape to cover the gaps. What is the best way?

Doc

[rrinker]

Woodland Scenics has a 'foam putty' that should work. Tape would work but you'd have to use something to feather the edges or it will be VERY obvious, even after painting, where the edge of the tape is. Sculptamold would probably work too, it's not as hard as plaster so it shouldn't crack unless the foam joints are flexed in some way.

--Randy

[ARTHILL]

I use Lightwieght Drywall mud, not as good as WS but much cheaper.

[dano99a]

I packed mine with small chunks of foam or used the clear packing tape method. After putting scenery on the area you'd never know there was a piece of tape there.

[Medina1128]

I bought some WS plaster cloth. It's not the cheapest stuff around, but it's a joy to work with. I found that instead of dunking it in water, then trying to keep something that has the consistency of a squid in your hands while trying to put it on your layout. I cut it into strips and lay it into place, then soak it with a spray bottle of water. Then for added strength, I brush a thin layer of plaster over that. Man, and it's a lot messier too. No plaster dripping everywhere; don't have to worry about getting plaster around the moving parts of a turnout, etc. I found a company online called *** Blick Art Supply, http://www.dickblick.com/ that you can buy the same amount of coverage in plaster cloth for just over half the cost of the WS cloth. AND you can buy it in bulk at an even bigger discount.
Another nice thing about foam cracks and crevices is that if you paint it with tan acrylic paint, then sprinkle ground foam over the wet paint, you have what appears in nature "naturally". I found a gallon of it for $5.00 in the discounted section of my local Ace hardware store. "We're not cheap... we're THRIFTY!!"

[randyaj]

If you are not wanting to go the plaster route( which I love btw) how about using expanding foam in the can? Spray it in the spaces and then file the excess to shape.
Good luck
Randy Johnson

[Bre2tSco2t]

Doc,

We used sculptamold over all our foam and cracks. It looks much nicer painted than the very flat foam board. More natural looking. Then we cut it out where a building will sit to get back to a flat, smooth, level base.

Sculptamold is very easy to work with and very for giving. I highly recommend it.

Bre2tSco2t
MGB - Where Life is nothing but FUN!

[MisterBeasley]

I filled my bigger gaps with some Liquid Nails for Projects, the same latex caulk I use to glue the foam to the benchwork. It sagged a bit when it dried, but I plan to cover it with plaster anyway, and this give me a solid base that the soupy plaster won't drip through.

[Anonymous]

For some tips and examples of how I've been using the plaster cloth, feel free to visit:

http://www.ironpeng.com/mrr/srr_Nscale.htm

Mike Tennent

[orsonroy]

For large gaps, I use "Great Stuff" foam in a can. Once it dries, it can be carved down into shape (but it doesn't like to be sanded).

For small cracks, I use latex or silicone caulk. I generally reserve caulk application for after the area has been contoured, since caulk can't be sanded or carved.

Finally, DO NOT USE TAPE ON FOAM. I've tried at least a dozen types of tapes on foam, and NONE will stay put permanently. The best I've found so far is Duct Tape, and that only SOMETIMES lasts for a few months. Even the Owens-Corning pink foam tape doesn't hold for more than a couple of months (considering all foam products are designed to be used behind drywall and never seen again, that's not surprising).

[cmrproducts]

orsonroy

I have been using Drywall paper tape for quite a while to cover cracks. I use the same paint that I normally use as the first layer prior to putting on the ground cover.

I paint the area with a thick layer of paint and then paint the back side of the paper tape. I then put the painted tape over the crack. I then paint the paper tape on top and then the rest of the foam in that area.

Once this dries it is effectively glued to the foam.

I have also used this method on my masonite backdrop to cover the seams between sections and once the paint is dry use the drywall mud to smooth out the surface and then paint the backdrop normally.

Haven't had any cracks in the backdrop yet and it is going on 3 plus years.

BOB H - Clarion, PA

[selector]

Every one of the above-described methods is excellent...and well worth doing somewhere on your layout just for practice. Personally, I have used the foam chips, gobs of latex caulk, thin purposed-carved wedges and strips, plaster cloth, and even a wire brush using strokes from the high side outward, and avoiding allowing the bristles to contact the lower foam surface.

Do 'em all. They're skill-building, easy, mostly cheap in the grand scheme of the total costs, and work!

[claycts]

QUOTE: Originally posted by randyaj

If you are not wanting to go the plaster route( which I love btw) how about using expanding foam in the can? Spray it in the spaces and then file the excess to shape.
Good luck
Randy Johnson

YES YES, it also glues the parts in place and can be cut to add rocks and such around a base. Get the MIN expanding not the 10 times like I did, WHAT A MESS!!!!
Take Care
george P.

[orsonroy]

QUOTE: Originally posted by cmrproducts

orsonroy

I have been using Drywall paper tape for quite a while to cover cracks. I use the same paint that I normally use as the first layer prior to putting on the ground cover.

I paint the area with a thick layer of paint and then paint the back side of the paper tape. I then put the painted tape over the crack. I then paint the paper tape on top and then the rest of the foam in that area.

Once this dries it is effectively glued to the foam.

I have also used this method on my masonite backdrop to cover the seams between sections and once the paint is dry use the drywall mud to smooth out the surface and then paint the backdrop normally.

Haven't had any cracks in the backdrop yet and it is going on 3 plus years.

BOB H - Clarion, PA

Ah, but drywall tape isn't what we normall consider to be "tape". We're talking about the self-adhesive sticky tape stuff here, which doesn't really stick, because the adhesive will eventually fail. What you essentially did was to take strips of paper and "glue" them to the foam with lots of paint, which will work (heck, I use paint to glue all sorts of stuff to foam).

[olequa]

QUOTE: Originally posted by orsonroy



Finally, DO NOT USE TAPE ON FOAM. I've tried at least a dozen types of tapes on foam, and NONE will stay put permanently. The best I've found so far is Duct Tape, and that only SOMETIMES lasts for a few months. Even the Owens-Corning pink foam tape doesn't hold for more than a couple of months (considering all foam products are designed to be used behind drywall and never seen again, that's not surprising).

I'll bet 3M blue masking tape would work. I'll bet it would stick forever. It's essentially waterproof and won't stretch. It has an adhesive that sticks well, but not too well, ie the tape can be removed. I use it all the time for a quick clamp, both in model work and general carpentry.

[orsonroy]

QUOTE: Originally posted by ghofmann
I'll bet 3M blue masking tape would work. I'll bet it would stick forever. It's essentially waterproof and won't stretch. It has an adhesive that sticks well, but not too well, ie the tape can be removed. I use it all the time for a quick clamp, both in model work and general carpentry.

Wait...you mean the blue painter's tape? The only thing I can get that stuff to stick to permanently is a newly-applied paint surface!

There ARE tapes out there that WILL stick permanent;y, but they're not common. 3M makes a double sided foam tape for the aircraft industry, to laminate skin sides to the frame. That stuff IS permanent, but only comes in 5000 foot rolls, and is pretty expensive...

[topcopdoc]

Hay guys thanks for all your help also “nice job” Ironpenquin your photos are a great reference. I am going to do some experimenting with some of the ideas all of you gave me. It is nice to know there are so many people out there to help you.

Thanks again,
Doc

[dgwinup]

QUOTE: Originally posted by MisterBeasley

I filled my bigger gaps with some Liquid Nails for Projects, the same latex caulk I use to glue the foam to the benchwork. It sagged a bit when it dried, but I plan to cover it with plaster anyway, and this give me a solid base that the soupy plaster won't drip through.

Just a quick [2c] worth on MisterBeasley's comment: I over-fill the gaps and let the caulk/adhesive dry completely. To trim the adhesive, I use a cheap, disposable razor knife that has a very flexible blade (I buy them at a dollar store - it's the one with break-off pieces). After trimming, you can add any scenery you want and it takes paint well. This method also has the advantage of glueing your foam pieces together, but can be trimmed out later if you make changes.

I prefer the adhesive over caulk because eventually (usually overnight) the adhesive dries.

Darrell, stickily quiet...for now

[Medina1128]

Mr. Penguin, Great pics! I guess it's about time to ask the wife for a decent digital cam and start documenting MY work, as well. I found it easier and less messy to cut the plaster cloth into strips, lay them in place, then soak them with a spray bottle with the old standby wet water (water with a few drops of detergent). I too noticed the holes in the plaster cloth, but found that while it's still wet, you can run your finger across it, starting from the center and working out towards the edges, it fills in the holes. If you're not going to add another layer of Sculptamold or plaster, that should be enough to "scenic". And it's still thin enough that it's easy to poke a small hole in it to put in signals, poles, etc. Because of my work schedule, I like not having to spend as much time cleaning up after a scenery session as I do actually working on the scenery, and plaster cloth IS that easy and clean to work with.
I add a thin layer of plaster to my plaster cloth scenery, and while it's still wet, I put some dry plaster into a flour sifter (my own, not the wife's) and sift some over it. It gives the plaster a texture that takes on the appearance of small rocks and dirt clumps. Nothing, other than glass, is really smooth in the real world.
Another tip I picked up, was that those small chunks of foam that you have from cutting it, or digging it out for texture, get left right where they are, and get plaster clothed over. Make nice little hills and mounds. I live in western Missouri, and even in small towns, there are rolling hills everywhere (not like Nebraska or Kansas). JUST KIDDING!! I don't need a bunch of hate mail from Cornhuskers and Jayhawkers!! [:)]

[Anonymous]

Marlon,

I'll have to try your method of laying the cloth and then spraying it next time. It does sound a lot less messier.

Mike T.

[bogp40]

Has anyone ever given any thought to using ceramic tile adhesive for bonding foam?
My son had used this for a school project, when all I had at the time was origional liquid nail- destroys foam for sure. He had bonded a couple of 1" layers, cut and shaped a 2" foam for the project. I was very surprised how well this worked and began to experiment with it. I tested glueing foam to foam, foam to wood, and plaster castings to foam with unbelievable results. Yes, liquid nails for projects is easier to use being in a caulking gun, but the variety of use and strength of bond from the tile cement can't be beat. I now have been using it for about 4 years on my club layout with no ill effects.
Laminating layers: use a cut shingle or paint stirrer as a spatula, then spread the glue with a notched trowel. You will find that the air trapped in the joint acts as a suction for initial hold and aids in drying. A large weighted section of laminated foam will be dry overnight.
Glueing castings (rock, portals etc) to wood, foam or plaster.
Have also used the adhesive like putty or joint compound to fill cracks or level out imperfections.
I feel that if this product was formulated to hold ceramic tile on a shower wall and withstand as much as 30 years of some severe conditions, it was worth a shot at trying it out for our purposes. I hear so much about so many glues and methods, I really found one that works for me. Note, I don't think this could ever replace caulking for glueing track to roadbed though. Give it a try, hardware stores carry small pint/ quarts if you are inclined to experiment.
Bob K.

[olequa]

QUOTE: Originally posted by orsonroy

Wait...you mean the blue painter's tape? The only thing I can get that stuff to stick to permanently is a newly-applied paint surface!

Umm....did you remember to put the sticky side down?

[nbrodar]

I use regular drywall mud, applied with my fingers. A couple things though, it dries slowly, and can crack when applied too thick. On the other hand, it's cheap and doesn't set rock hard like plaster, so it takes paint well. One more thing, it is slightly water soluble when dried. This makes it easy to alter the final texture, be it a smooth road, rippled pond or rock strewn ground.

nbrodar

[Anonymous]

QUOTE: After putting scenery on the area you'd never know there was a piece of tape there.

I would worry that when the adhesive on the tape dries up it will pop up. Unless ther's alot of scenery material on top.