Building a hill/mountain with tunnel - I NEED SOME QUICK ADVICE/SUGGESTIONS

Hi All,

As some of you may remember I have been struggling with an expansion of my layout and what to put in the new area.

I have made a decision; in the corner of the expanded area I’m going to put a hill/mountain with a tunnel.

I have started the build by making some ribs using foam core board. I went with the foam core board because it is lightweight and after having openings cut in it, it remains strong.



Using a hot glue gun I attached cardboard strips to the 4 ribs to create the form of the hill/mountain.

Please note that a few more strips of cardboard have been added since the photo. With luck the tunnel portal will not be falling over when finished.

The cardboard strips were then covered with paper towel attached with white glue.

Yes I did the papering with the hill sitting on the table. I have tested the fit in the corner multiple times during the covering. The brown lines are the cardboard strips showing through the paper where some of the glue is at.

At this point I need some advice/suggestions.
The final covering of the hill is going to be made with a product called "CelluClay" which is a papier-mâché mix, with a few real rocks thrown in.

My question here is, since the current state of the hill is a bit flexible and possibly weak, should I cover it with strips of paper towel soaked in a plaster?

I’m thinking that the plaster soaked paper would create a hard shell, which would serve multiple functions:

• Make the form stronger
• Make the form ridged
• Make it easier to attach the wet papier-mâché by providing a bonding agent.

Or should I just cover the hill with the papier-mâché?

Any thoughts on the matter?

Thanks,
Gary

 

Thanks Rick,

Something that I did not think of but should have.

:sad:

Gary

 

I'd buy what Rick said , and you could bump the test to the hill so that is not lost either. or use it to test other things on .... then add to the hill ..

 

Something else to try is to stuff plastic grocery bags with crumpled newspaper so that you can shove those under the mountain with just enough tension to keep the weak places from sagging. Then lather on the celluclay and once it hardens, remove the under-structure bags and situate the mountain properly.

I would not rely on plaster cloth unless I layered it about four-ply. Even so, wetting it may render it weak again, and the celluclay may want to cede moisture to the dry plaster cloth. The wisdom is that you spray down plaster with water first before spraying your glue mixture in advance of sprinkling ground foam so that the glue doesn't get sucked into the dried plaster right away. It's a catch-22 sort of thing.

Next time, if you don't mind the experiment, use aluminium window screen and hot glue for the framework, and as I have done, resort to the grocery bags below the screening for support. I found it worked very well for my last layout, and I will use it again for my current build.

 

I was thinking about the crumpled newspaper, but stuffing them in the grocery bags is a idea that had not come into play. We have more the enough bags here that I would not need the paper. I could just stuff bags with more bags.

Thanks,
Gary

 

I will have to rethink taking my plastic bags to the recycle bins at the store.

I've seen, on this board, the use of wide masking tape to cover card board strips to form the hills. It gave a good representation of the final form and I would think it would absorb far less of the plasters moistere. Though it would like to cling to the plastic bag supports.

 

Unless they are the kind with the reinforcing fiber mesh built into them, paper towels have no strength when wet. Also, Celluclay takes a long time to harden, and has little strength during the process. Perhaps rather than a layer plaster you should add a layer or two of paper (magazines, newspaper, or brown paper bags) strips soaked with white glue, and let it harden before adding the Celluclay. Use the Celluclay in thin layers so that it will dry all the way through (in thick batches, Celluclay will stay soft in it's center for a very long time!). I've heard that John Allen and Howard Zane both used this glue & paper method on their layouts. Using old plastic grocery bags for support under the tunnel is a good idea, it will help protect the track below from drips of whatever material you decide to use for your scenery "shell".

Bill in FtL

 

Actually, my first layout "mountain" in 1980 was chicken wire and flour paper mache' with a few 1x1 sticks to hold up the peak ... it held up pretty good up to when first wife took base ball bat in hand and rearranged the tunnel in it, boy golly she had the guys in the mine running in all directions ......of course , in that situation nothing can stand up to the wrath of a mad wife . So, it really is not so much what you use to make your mountain or hill or valley .... just don't make her mad at ya..

 

That's right.. paper towels soaked in plaster will build a shell over your ribs & support grid. You may want to put some waterproof material(s) over the cardboard or it might sag.
The process I used was different from yours though. I use Great Stuff to build my mountains. My tunnels are finished inside with lighting and my mountains fit over the tunnels (like a glove covers a hand). This way I can remove the mountains and the tunnels to access the track and maintenance the tunnel lights and light wiring of structures built on the mountain. I have a several videos that show the process, however, I am new to the forum and cannot paste my website. You can click on my name/profile and perhaps find the url to my blog (?). I will paste a picture here of the tunnel here:

 

Thanks for the tips on the Celluclay. I was reading the instructions today and was wondering about the drying time.

The paper towel is just the cheap type found in the kitchen.

Gary

 

I have used Great Stuff while working on the house and it sticks to everything. What did you use as a barrier between the mountain (Great Stuff) and the rest of the layout to keep it from sticking?

The idea of using Great Stuff to build the mountain is intriguing. At this time my major investment is time. Foam core board, hot glue, white glue, paper towel and cardboard were already in great supply.

Gary

 

Hi Gary,

For using Great Stuff or liquid polyurethane foam such as Mountains in Minutes, some of the best methods I have seen were demonstrated by Joel Bragdon of Bragdon Enterprises, in his clinic on "Geodesic Scenery" at an NMRA National Convention some years ago. Basically, he uses a sheet of bubble wrap laid flat with the foam spread on it, then quickly covered by a sheet of clear plastic similar to cellophane, which is pressed with a flat sheet (like plywood) and some weights. When the foam stops expanding, but before it's fully hardened, he drapes the bubblewrap laminate over his forms to create the shape of his terrain, and lets it fully harden. Then he adds paint and ground cover materials, making an exceptionally lightweight, yet rigid mountain structure. For more info, check out: <http://www.bragdonent.com/articles.htm>

Bill in FtL

 

Hi All,

First let me say thank you to all that have provided suggestions and tips.

Based on the information I was provided and some of my own thoughts, I moved on with the project. In doing so I

1. added bracing between the foam core ribs;
2. added a few upright braces to keep the peaks from collapsing;
3. decided NOT to cover all of the hill with Celluclay but will use it where I want to put some rock outcroppings along with some real rock;
4. added a view block at the right end of the hill (seen middle of right edge of photo);
5. worked around the opening for the tunnel portal making it a bit more vertical so the portal fits flat against the hill; and
6. decided to use Zip Texturing to cover the paper toweling. The color is not as dark as I wanted it, but it is not sheer white.

The Zip Texturing

1. made the covering stiff
2. created a lot of detail (ridges and valleys)

Still a ways to go before I consider it finished, but at this point I am happy with current state and how it looks. The first thing I need to do is to attach the tunnel portal so I can stop using the big yellow head pins.

Again thanks to all that provided help and suggestions.

Regards,

Gary

PS: The plaster is still damp in the above photo.

 

Looks good Gary. I cheked out you other sites and saw your photos of the Garden ... My youngest lives there and we went on vacation down there last year , great place to visit . I like your photography as well !!

 

Thanks Guys, on all counts.

Gary

 

Hi, I've nothing to say about scenery and mountain construction on this layout, however something puzzles me: the turnout at the tunnel entrance, meaning that the line becomes double entering the mountain. In the prototype, it's rather the opposite: as carving a tunnel is expensive, usually, at least at the beginning of a railroad line a double track becomes single in a tunnel, even if that creates a bottleneck. Look for example at a railroad such as the Tehachapi Pass, you'll understand my statement.

Dom

 

Hi Dom,

I understand what you are talking about.

Here are some of the reasons for what I'm doing:

1. I just expanded the bench work. See this thread (Thoughts needed on possible track plan change on the GD&R)
2. The change of the bench work resulted in
   1. more area to scenic
   2. relocation of 2 online customers
   3. expanded the main line track by about 50% (used the existing branch line as part of the expansion)
   4. changed my operating plan
3. The double track was already in place before the expansion and I was too lazy to remove it. See the above mentioned thread.
   1. I could extend the double track a few feet. Let me think about that....
   2. Now I can say that at one time there was double track on the outside of the tunnel and for what ever reason the railroad removed the double track up to the tunnel.
4. The other end of the double track now ends at my yard. See this post in the above mentioned thread
5. I wanted to fill in the new bench work with something other then buildings and remove some of the "plywood plains look.
6. I do not want to have switches inside the tunnel.
7. I could have used a cut and not a tunnel. I have a cut at the other end of the loop and was wanting to try something different.
8. I operate that area using the non diverging track, preventing the use of a "S" curve on a regular basis.

Thanks for your input.

Regards,
Gary

 

Gary, I used damp paper towels as a separator between Great Stuff and anything I did not want it to touch or weld to. For example, I laid paper towels over my custom tunnels to prevent it from sticking to tunnels, yet it formed over the tunnel and fit it like a glove. To form back and sides of mountains I just placed cardboard that was covered with wax paper like building forms for concrete work in real life construction. After spraying out Great Stuff, drying, and mountains formed I then just removed the cardboard forms. Must run.... kids calling. Ask if I can tell you more.