Expanding / spray foam for mountains

I took the new cloth dowstairs this morning, and was greeted by this:

The foam I had piled up, continued to expand and dry over the past two days, and it pulled it off the lattice and bulged upwards.  The tower in the picture was actually leaning about 15 degrees or so to the right! (In my haste to fix what happened, I failed to get a picture.) Luckily there was enough foam that I was able to cut off the top to create another flat area for the tower. I used a "Japanese flush cut saw" (used for cutting trim around door frames when installing hardwood or tile.) I also trimmed off the "round" that was directly over the tunnel portals. 

Issue number two: either the shrank or the plaster cloth swelled! ��

You might also be able to see on the picture above, that it's worse on the left side. I don't know if I can re-wet it, to get it to conform to the current shape or not?

I again would recommend letting the foam dry for a good 72 hours before adding anything else, covering with anything, etc. 

With my schedule this week, and daughters birthday on Saturday, I won't be able to get back down to it till Sunday, and honestly I think the additional drying time couldn't hurt. 

Chris, I am sure you can fix it, You have shown in the past what great work you do. I know you will make it great!

I tried this approach for a tunnel base and mountain on top to hide my electric service and FIOS gear.

I use 3 contours out of luan and tied them together with 1/2" x 1/2" supports to provide the vertical height and general shape. Then, I stapled on aluminum window screen to create landform shapes by pinching and to provide something for foam to grasp.

It looked about the same when I was finished and it needed days to harden because of the thick application.

The cutting and shaping became tedious. I visited a few 2nd hand stores and found some electric carving knives. These worked nicely. But, slow and the long blades were tough to shape with.

Then, I read a post in a thread where a fellow forum member broke out the angle grinder with a cutting wheel. This worked out well. I used the carving knives for detail.

It all took too long to discover the best cutting method and I have not finished it.

I only did it this way because I needed a hardshell shape that was lightweight and removable to access the breakers when needed. It worked well for that.

Now the layout is ready for a rebuild, so I have to decide if I'll reuse it or try piecing together 1" and 2" foam insulation board.

I used expanding foam on a small layout as a scenery base once. I waited a week before covering it with a layer of plaster for final texturing. 

It continued expanding over the next two weeks cracking the plaster base. Not a successful try!

That, the mess, and the expense of the spray cans made me go back to more traditional materials for scenery construction.

Jim

You CAN get non-expanding foam. But, I agree with Jim. Expensive, messy, imprecise. Lots of good alternatives. Good experiment, though!

I disagree with expensive and messy. Wal-Mart stocks the cans now. Don't use the black or large gap stuff. Now that I know how to attack it, it can be precise.

Plaster is neat? Hydrocal rock molds take a lot of time. Sculptamold is expensive.

The big advantages are having a hardshell that you can stand on, work on it in another area and place it where you need it or for modular railroads, be portable and durable. (which is one of my needs) 

I suppose I'll have to finish it to see what the final result looks like.

I got the idea from Dave Frary's book. He needed large mountain features for a museum display that could be removed for access to infrastructure. 

Like most terrain techniques, each have their place. Not many are inexpensive. All take practice for a good result.

I would suggest to anyone wanting to make this she'll removable, to put down some sort of barrier between the table and foam. It will adhere to the table. You could "unstick" it with a putty knife of something similar, but you would have to plan out your supporting structure accordingly. 

Jim- thanks for the info about it continuing to grow. I think I'll give it another week or so before I do any more plaster cloth. 

Does anyone know if I can re-wet the already laid cloth to get it to conform to the new shape?

I took some time off this week, and headed back "onto the mountain" . (Pun intended) 

After I cut the thick area flat, it exposed the center, which was still not fully cured, to air, and I had more expansion, but in the opposite direction. 

Flattened again, then finished laying the plaster cloth. After doing that, I was re-watching Eric Segals videos, and he mentioned using joint compound to fill in gaps around his rock molds, I needed to fill in all the holes from the cloth. So I got a bucket of mud, and went to work. Below is a side by side of before and after the application of the mud. I did the whole mountain, using my finger to spread it.  I wanted to retain as many nooks an crevices as possible.

Im going to continue on with his techniques for weathering, color, and scenery. 

You have done great work with this product!

I tried the expandable foam when it was debuted by Mountains in Minutes on my HO layout years ago. You mixed the resin and epoxy together and put it in a rubber mold... The stuff stuck to everything! The first mold I made of the stuff ruined the mold by not releasing out of it. I had to use car wax to make them come out.

As you know this stuff sticks to EVERYTHING! And yes dimensionaly it is very unstable. With the advent of extruded foam board I elected to move on... 

I am glad to see it has dropped in price, but I am going with the stacked foam with paper towels dipped in plaster... it just seems more manageable. 

Good Luck and keep up the good work!

Looks great Chris, I think when everything is said and done your going to be proud of yourself along with everyone else! Keep up the great work as I am interested on how it turns out using the spray foam!

The last time I used this for some hills and tunnel entrances I used parchment paper in spots that I didn't want the foam to adhere.

I had the same thing happen to me...the gooey inside after thinking it was all cured. I determined that keeping the nozzle closer to the surface and making smaller runs of foam would help on the next project.

I like how the mud coating finished it. I was trying to decide if that step would be needed. Does it feel like the mud has a good hold?

Thank you sirs, for the kind words!

Moonman- the mud itself doesn't stick to the foam that well. I had a few spots of just bare foam and it didn't seem to want to hold. I'm sure that I could go back today and add another coat over those areas, since the light coat has dried, but those spots are in the back. The plaster cloth over the foam did a good job of conforming and taking away all the rounded shape left by the foam.  

If I end up doing this again, I think I'm just going to use the paper towels dipped in plaster, to save a step in this process!

Chris, if you just give it a little rough sanding to take the top smooth stuff off it will stick a lot better!

Anyone know why the pics in my top post dissaeared and how to get them back?

Mo985 posted:

Anyone know why the pics in my top post dissaeared and how to get them back?

Post the issue in the tech support area or email the editor

I bought a can, thought about it and ended up filling holes and cracks on the outside of my home.

Problem with this stuff is once you start spraying you need to use up the whole can at one time. You can't store it after initial spray. I started running out of holes.............

Joe

Joe, If you look around there is some expanding foam that is water clean up. If you rinse out the tube and the spray nozzle when your done you can reuse it till its all gone. I have used several cans of it.

Mike:

Thanks!

Joe

The only water soluble foam I have seen has been the environmentally friendly packing peanuts used to protect items being shipped. It is soft, and makes a good cushion, but when wetted, it makes a gooey mess. Is this the same stuff? I was told it was soluble because it was made from starch, which I would think if it were used on a layout, would attract roaches & silverfish.

I have had also had pretty bad luck with both plaster and Sculptamold, initially it seems to go on well, but after 6-12 months begins to break down and soon reverts to it's powdery form when touched. Unlike the original plaster however, adding water to the resulting powder doesn't regenerate it, it just makes a messy, white, "mud" that needs to be cleaned up.

Bill In FtL

Joe, Your more then welcome.

Bill, I know its out there I have used it several times around the shop to plug old holes in the siding, then you just trim it, sand it and paint and your done. It all cleans up with water.

Here is an example.

http://images.lowes.com/produc...798/070798188266.jpg

I painted with gesso, and even though the consistency was fairly think, I only used about 3/4 of a 16oz jar.

What little holes left that didn't get filled in with the joint compound, got filled in with this. 

Next, I started coloring. As I said previously, I was going to use Eric's method. I got some powdered black tempera paint, and used one of the cheap "chip brushes" to apply it. It seemed to just slide off, and pool in the crevices. Then I got a sponge brush, not completely soaking wet, and started daubing. Well, what I didn't think was a lot of paint, was! It started getting really dark. I even changed my water out 3 times, to cut down on the amount of color. I ended up brushing most of the rest of the paint off of the areas I had not been in yet, and using the little hidden in the nooks and crannies. 

I dont think I'm going to do the wash of browns like he did, I have quite a bit of places that it will pool up at. I don't know, maybe I'll try it out on a not seen side just to see.

You may want to drizzle something from the top center and let it run. It looks like a natural erosion cut already. The few angular outcroppings more grey and the rest perhaps more toward umber and browns.

Go at it with a chip brush and blend the colors. It will look good.

Painting Rocks with Dave Frary

You can always paint over it if you don't like it.

I started adding a bit of ground cover this weekend, and after looking at it long and hard, decided it needed to be darker.

You can see the color comparison, I ran out of wash. I had mixed up some browns to put under the turf, and so I had to blend the grey back into the already done areas.

Tonight I made another wash, finished the rest, then went and added my brown in. Much better in this order. 

I look at this as all good practice. Once the kids move out in 8-10 yrs, we'll either move, or I'll commandeer the rest of the basement for a new layout!

Tonights helpful tip, make "more" wash than you think you'll need. If you have to make a second batch, the colors won't match! I guess it only matters if you're OCD like me. 

Part of the left side being darker, is the position of the light in the ceiling. The left is under a shadow from the upper portion of the mountain. 

Oh yeah, I picked up a few trees just to see which I thought looked better, Conifir, or Decidious. Any thoughts?

Mo985 posted:

I started adding a bit of ground cover this weekend, and after looking at it long and hard, decided it needed to be darker.

You can see the color comparison, I ran out of wash. I had mixed up some browns to put under the turf, and so I had to blend the grey back into the already done areas.

Tonight I made another wash, finished the rest, then went and added my brown in. Much better in this order. 

I look at this as all good practice. Once the kids move out in 8-10 yrs, we'll either move, or I'll commandeer the rest of the basement for a new layout!

Tonights helpful tip, make "more" wash than you think you'll need. If you have to make a second batch, the colors won't match! I guess it only matters if you're OCD like me. 

Part of the left side being darker, is the position of the light in the ceiling. The left is under a shadow from the upper portion of the mountain. 

Oh yeah, I picked up a few trees just to see which I thought looked better, Conifir, or Decidious. Any thoughts?

Mo 985 - great looking work!!  I'd go with a variety of trees.

Don't sweat the color difference Mo.  Rocks ain't all the same colors. 

Lookin' good. 

Really taking shape Chris, I also sent you a private message.

Bob

I use it all the time.  What works best for me is to carve it with saws, steak knives and blades.  Case in point, Big Thunder Mountain Railroad:

This was the starting point.  A Life-Like tunnel, a few cardstock structures and the train, which is also made of 65lb cardstock.

I inserted a few random dowels into the tunnel to give the foam something to stick to.  I tied it all together with foamcore hot glued in place.  These "modules" need to be lightweight and storable because they're only used six weeks a year on my Christmas layout.

I stuffed the gaps between the spray foam, which has already been carved, with crumpled newspaper, packing peanuts and the like and glued torn strips of craft paper over top to give me a lightweight shell.

I use inexpensive acrylics for coloring.  For this project I used a simple sand color as a base, and then applied washes of thinned acrylics to bring the mountain to life.

Trestle bent installation.  (This is a roller coaster!  )

Splash Mountain:

I used minimally expanding latex foam on Splash Mountain and I'd never use it again.  It took weeks to stiffen and it's still far too delicate.  Btw, the water, trees and log ride vehicles are made of hot glue.

Here's one that may surprise you:

Couldn't think of any other way of making a tree large enough for the Swiss Family Robinson Tree House.

Becky

Becky,

Awesome work!! How did you make the trees? Do you have a tutorial posted? Could you share the process with us? My wife saw them and was very intrigued!!

Chris

Mo985 posted:

Becky,

Awesome work!! How did you make the trees? Do you have a tutorial posted? Could you share the process with us? My wife saw them and was very intrigued!!

Chris

The evergreens are very simple.  I use a plastic greenery that you find most often at Christmas time in craft stores.  I think it's juniper but I wouldn't stake my life on it.  Then it's just hot glued on to a dowel or even just a piece of the stem the greenery came on.

Trees like the dead ones on Splash mountain become easier with practice.  Start by making a tree armature by twisting loops of 26 gauge floral wire together.  Uncoated works best for me, the coating just makes the wire harder to twist.  I like to make 4 loops per division of the tree, either loosely with my hand or for larger trees I make a jig to wrap the wire around.  4 loops gives you a substantial main branch coming off the trunk plus 2 then 4 smaller branches.  Loops make it easier because you can twist them and then cut the ends open for the smallest branches.  I start with the top canopy branches first and twist the loop divisions just enough to keep them separate from the next level down.  But you don't want to twist them all the way back to the base of the tree at this time because then it's too hard to twist-up the main trunk.  Wait till you get to your last (lowest) row of branches then twist everything all the way to the bottom.  Here's a tree armature:

Next comes the bark.  I like to use an old plastic bottle cap as a temporary stand for the tree.  I bore a hole through the center just large enough to admit about a quarter inch of the armature.  If you're going to mount these on a thick base you can make the mounting peg as long as you like.  But most of mine get stuck into foamcore bases so I keep them short.  Start with a few big globs of hot glue to mount the armature to the temporary base.  The plastic caps I use make it very easy to pop the tree loose when it's ready for mounting.

Coat the metal as much as you can but leave a few bare spots for character and give time for the glue to cool.  If you try to do too much at one time you'll end up with a hot steel armature that will melt off everything you did previously.  So work one side of one branch and then move to the next one while you let the work cool.   Besides, hot glue goes on clear and you can't even see what you've done until it cools and whitens up a bit.  Notice too that I've used the glue to give the tree a root structure.

And now we paint.  I use acrylics, the el cheapos you can find everywhere that has even the most generic of craft departments.  I've had the best success with Apple Barrel.  I like to use a tan or beige as a base and really glom it on thick, and I mean glom!

Then I do 2 washes, after the base coat dries of course.  First comes gray.  I don't have a specific recipe that I follow, every paint seems to be a bit different.  50/50 is a good place to start, but you'll probably have to experiment a bit.  What I'm looking for is a bit of a "fogging" with just enough of the brown showing through.  I know, that's a bit vague.    Here's a photo:

Notice that I didn't entirely cover the steel with the glue.  That's where the black wash comes in, and this one should be very thin.

I was amazed at how much detail I got by doing such a simple series of things.  And I wasn't even trying very hard either.  It all just fell into place with very little help from me. 

Then you can flock to your heart's content.  Or leave them as is for a fairly convincing denuded tree.

When planting time arrives, I stick the blade of a small flat head screwdriver between the cap and the "roots" and pry the tree loose.  The best part of these trees is that they remain flexible.  I can't speak to the durability of the paint because I haven't been doing them for very long.  But a tree that I can reshape at will is a big plus.

Becky