Questions about using styrofoam.

[shortline fan]

The April 2007 issue of MR detailed how to install Tortoise switch machines under 2" foam.  I've had great results using foam myself.  I find it easier to layout my track plan right on top of the foam by using a marker to trace around the pieced or temporarily glueing photocopies than tracing it on plywood and then cutting.  I build up track, structure bases and roads on cork to obtain the proper height.  I am about to build a new layout using traditional L-girder methods with a 1/4" birch plywood base under the 2" foam.  I can cut down and even through the plywood if needed for lower areas and glueing foam underneath the plywood.  On top you can glue pieces of foam sandwiched together or use them as an underlay for plaster soaked towels or the Woodland Scenics gauze variety for larger mountains or hills and Sculptamold for small terrain changes.

[rrebell]

For doing the planning I use the actual turnouts and 2nd hand atlas sectional track, kinda overlay the stuff, gets the general shape right for the cork.

[CNE Runner]

The question I have for all is painting the Styrofoam after it is in place. I have a fold-down layout that features a 5/16" plywood base. To save weight, I decided to forego my usual underlayment of Homosote and went with 1" Styrofoam. After gluing down the Styrofoam, I painted the entire surface with latex tan paint. My problem is that the paint will stick to, and is removed by, anything that is set on the layout for a couple of hours or so.

Understand that my track is already glued down (and I ain't going to remove it). Will this cause problems with track/roadbed adhesion in the long run? Will my future scenery additions (grass, dirt, bushes) be compromised by the paint? This was my first excursion into Styrofoam sub-bed and I think I would have been better served sticking with Homosote. No one was of any assistance, at our local Lowe's, because Styrofoam insulation isn't ordinarily painted. Any thoughts?

[rrebell]

You got bad paint, it will cure eventually. Had that problem back when latex paint was not common. I use latex paint (flat) all the time over foam. Since you are going to cover most of it I wouldn't worry.

[CNE Runner]

Thanks for the reply rrebell. I lie awake some nights thinking of all that expensive Peco trackwork crashing to the floor - taking the scenery with it. I think you are correct as the track, that was glued down to the Styrofoam with latex caulking, seems rock solid. OK...on with the ballasting!

[rrebell]

Caulk and track ain't going no where.

[grayfox1119]

As for paint on foam, you must use LATEX based paint not acrylics. Acrylic based paints, such as those in spray cans, will eat into the foam. There are now LATEX paints in spray cans, so look for them if you want to go this route. I chose not to, I use a roller because I was in a windowless room. I used a floor fan anyways to keep the odors/fumes out of the room and out the open window in the next room.

If you have a layout in the basement, and there is in most homes a furnace ( oil or gas fired ) located there also, you must be VERY careful of fumes from ANY sprays, paints, chemicals, etc. Your air intake for ignition of your furnace could make things go very bad in the basement in a hurry. For this reason, I decided on the side of safety and had a sealed air intake pipe installed to the outside of the house for furnace combustion air intake. Very inexpensive 4" pipe and 4" cored hole in basement wall, only took 30 minutes to install.

[rrebell]

As for paint on foam, you must use LATEX based paint not acrylics. Acrylic based paints, such as those in spray cans, will eat into the foam. There are now LATEX paints in spray cans, so look for them if you want to go this route. I chose not to, I use a roller because I was in a windowless room. I used a floor fan anyways to keep the odors/fumes out of the room and out the open window in the next room.

If you have a layout in the basement, and there is in most homes a furnace ( oil or gas fired ) located there also, you must be VERY careful of fumes from ANY sprays, paints, chemicals, etc. Your air intake for ignition of your furnace could make things go very bad in the basement in a hurry. For this reason, I decided on the side of safety and had a sealed air intake pipe installed to the outside of the house for furnace combustion air intake. Very inexpensive 4" pipe and 4" cored hole in basement wall, only took 30 minutes to install.

Acrylic is water based so no problem with foam!!!!!!!!!!!!!!!!

[modelmaker51]

As for paint on foam, you must use LATEX based paint not acrylics. Acrylic based paints, such as those in spray cans, will eat into the foam. There are now LATEX paints in spray cans, so look for them if you want to go this route. I chose not to, I use a roller because I was in a windowless room. I used a floor fan anyways to keep the odors/fumes out of the room and out the open window in the next room.

If you have a layout in the basement, and there is in most homes a furnace ( oil or gas fired ) located there also, you must be VERY careful of fumes from ANY sprays, paints, chemicals, etc. Your air intake for ignition of your furnace could make things go very bad in the basement in a hurry. For this reason, I decided on the side of safety and had a sealed air intake pipe installed to the outside of the house for furnace combustion air intake. Very inexpensive 4" pipe and 4" cored hole in basement wall, only took 30 minutes to install.

Acrylic is water based so no problem with foam!!!!!!!!!!!!!!!!

Actually, there are also solvent based acrylic paints as well available at hardware and paint stores. You have to specify acrylic-latex if you want waterbased acrylics in a paint store.

[CNE Runner]

Thanks for the advice. I have an additional question: What is a basement? I live in northeasern Alabama...basements are rare. All kidding aside, I would kill (or nearly so) for a basement or anyother area that would allow me to keep my layout useable and in a controlled environment for more than 3 days. I have to deal with what I have and that means not running trains in the heart of the winter or summer; removing wooden structures to the house, and folding up the layout when I am done "playing".

Your advice about an external air source for a furnace is on target. Most newer furnaces are equipped to have an external air intake installed. I would add one should never spray paint (or air brush) in an enclosed space unless one is using an externally vented spray booth. Depending on the CFM of the blower, this may or may not mitigate the danger of explosion.

In addition to my original post and for the record: I did use an acrylic-latex paint (Valspar Universal Umbar Interior Flat) but brushed it on instead of using a roller...which would have been easier and considerably faster. The painted surface was allowed to air dry for at least two days before anything was attached to it.

[rrebell]

Note, you got to be careful about your paint, been around paint long enough to know to test first and even then every can or generation of spray can be different. Even in hobby paints, remember one that just got hard in the bottle (they didn't clean the nozzles properly at the factory). Believe it was called accuflex but I could be wrong.

[mopac rick]

I love these products. I have used several types or brands very successfully. I usually glue the foam to a ridgid base pf plywood and the shape with wood working tools. For a source of free foam check out commercial roofing companies, they regularly have large scaps left over that end up in the dump. I once picked up a whole truck load of 4'x4' pieces ranging from 6" to 10" thick.   Rick