Sealing Homasote Really Necessary?

On Fri, 4 Jul 2003 20:24:24 UTC, "Steve North" wrote: 2000

First, latex paint or just about anything else short of dipping the roadbed in plastic will not seal it. It will retard the transfer of moisture but will not prevent it. If you seal it you must seal all exposed surfaces or you will get differential absorption and distortion. In a relatively stable environment sealing is probably a waste of time and effort.

A better approach is to spread out the uninstalled Homabed in your layout room for a few weeks to adjust to the environment and then lay it without sealing.

I've had homasote on my layout for 40+years. Sealed it w/shellac including all the edges. No probs in spite of weather in WNY. Don

snipped-for-privacy@aol.com (Maycop) wrote in news: snipped-for-privacy@mb-m26.aol.com:

I've read so much about homasote being such a great material for sub- roadbed. However, I'm still looking for it in my renovation center. Perhaps someone might be able to tell me what this product is called in Canada - Montreal in particular?

Much obliged, Bobby

Bobby,

I actually may be able to help with this one. First, though, did you mean roadbed or sub-roadbed? Homasote is much softer than plywood, and I've heard that it (Homasote) isn't well-suited for sub-roadbed because it will tend to sag over time. In any case, I don't know if they have any dealers around Montreal, but you can try the Homasote Company's dealer locator

to find out. Incidentally, I'm not using Homasote directly, but Homabed which is Homasote that's been cut specifically for use as roadbed. California Roadbed Company (the maker of Homabed) has a dealer list on their web site and they also sell directly to the consumer. My guess is that even if there's no dealer close to you that you could order from their web site if you decide to use Homabed instead of "raw" Homasote.

Bobby....I found some at the Home depot on St.Jacques St. W. Gene

I have used Homabed since 1987 and have had no problem with it. The layout is in Minnesota basement. The house is air conditioned, but there is no other humidity control. The Homabed was 'glued & screwed' to 1/2" plywood sub-roadbed. No shellac, varnish, or painting was done before the Atlas code 100 track was laid. A previous layout was built in my parents home using sheets of Homasote over 3/4" plywood. I would suggest using the Homabed - much less 'dust' than from cutting up sheets of Homasote!

Jim Bernier

You can contact them at snipped-for-privacy@homasote.com to learn about distributors in your area.

Sealing Homasote is not really meant to be a protection from local climate, but to act as a partial sealant for ballasting. Most ballast applications involve spraying spread out ballast with soapy water (Palmolive dish soap is excellent). Then a 50/50 miixture of Elmers white glue and water (and also with some wetting agent added) is then applied to track. Homasote is an excellent product and has tremendous repellant qualities already. If you are cutting Homasote in sheets and specific shapes, the extra sealant could be optional. If you are using curfed Homasote which is cut down strips with cuts in both sides for flexing either on plywood sub or splined roadbed.......sealing is almost a must as the individual segments (curfs) will most definitely warp some. Sealing is quite easy............bottom is rolled with yellow Elmers which is the attachment to sub roadbed. Then tops and sides are painted with gloss or semi gloss laytex paint...........color of your choice. I hope I was of some help. This method has worked flawlessly for me over many decades. I understand many modelers have different approaches, and that is fine, but sharing what has worked for me is most enjoyable. HZ

-- Howard Zane

5236 Thunderhill Road Columbia, MD 21045

I haven't sealed mine. Homasote is a ground up paper product with little real strength. It deadens sound and takes track nails well, but it wants a sheet of plywood underneath it to keep it flat. If you lay a sheet of Homasote on top of joints spaced 16" apart, you may find perceptible sag in-between the joists after a year or two.

David Starr

Steve North wrote:

Yes, 12" is a better idea. As for sealing....Painted with latex primer (Kilz or Zinsser) as a guard against absorbtion of ballast/ scenery water/white glue will keep it from getting wavy after evrything dries. I have done this for a long time and it does help alot although it still gets a little rippled. I have heard of the shellac and mineral spirits treatment but that is just too fumey for me when there are alternatives.

-John

Hey John, Kilz and Bin Sealer are solvent based primers, used for sealing badly stained areas. I believe one or both are actually just pigmented shellac. They are not latex paints, clean up is with subterps or thinner. An inexpensive interior latex primer would probably be a better choice for most modelers, as there would be little to no fumes. Kilz and Bin Sealer must be extremely well ventilated for alteast 24 hours. Take care. Jeff

--------------------------------------- Steve,

This very question came up earlier on another list and here is what I replied, for what it's worth:

-------- Original Message --------

'''''''''''''''''''''''''''''''''''''''''''''''''' This is simply not true but seems to live on as an "urban legend" within the model railroading community for some reason. One individual on some list actually immersed a piece of it in a bucket of water, taking careful measurements before and after days of it soaking, and could find no measurable change in dimensions. We have left scraps of it outside in the weather for months and nothing has happened to it here in the midwest. Almost all of us in this area use Homasote and NONE of us has ever purposely sealed it, and have experienced NO problems whatever. I even had a small plumbing leak puddle down from above on a section of the layout directly on raw Homasote. I got the water up and ran a fan on the area and the stuff never budged, rippled, swelled, or caused mis-alignment of any track. It was as if the water incident never happened. OTOH, dimensional shifting HAS been noticed in the plywood the Homasote is typically attached to on our layouts. Perhaps this is how Homasote has gotten the misdirected blame for past problems.

Paul - "The CB&Q Guy"

I would second that - I have been experimenting for a couple of years with the fibrous material inserted in expansion joints in concrete structures. It's a bit like felt and when applying ballast the diluted glue soaks right in, requiring more glue than normal.

On a side issue if anyone is building a lauout in the garden this stuff might be of interest. I have had a section of this stuff screwed to some ply wood sitting outside for a couple of years with some track attached in various ways. It's been frozen, cooked, soaked etc and hasn't bulged or distorted in any way. I used it for a couple of indoor layouts because its easy to cut a chanel into it to hold the wire-in-tube point/switch controls (actually you dig out the chanel with a pair of needle nose pliers as it tends to fray if you try and cut it). So far I am pleased with it. In the UK there are quite a few people building layouts (HO track) in the garden and the quiet running this material provides might be of interest (I happen to like hearing the wheels go over the rail joints). It comes in eight foot lengths (at least at my local store) and widths ranging from four inches to about eighteen inches. I attach it to the plywood (or whatever) using countersunk head screws. Indoors I have used both plywood and also (in a garden shed) ready-made Melamine coated shelving as the sub base, the latter sitting on spur shelving as vertical space was an issue. Outdoors I found I had a few problems with the glued ballast lifting off the base during freezing conditions where it was laid flat on the surface. In areas where I had pushed a nail into the stuff to make a 'key' this didn't happen. One length of track is sitting in Peco foam ballast underlay so to solve the problem of gluing it down I drilled pairs of holes at intervals of about a foot and used 30 gauge stainless steel wire looped over a couple of ties and twisted together under the sub-base to hold it down. The test board is sitting up against a wall and the material is still attached and the track is still there. A slight plus is that you don't have to paint the rails as they (Peco nickel silver) weather naturally and the Peco foam has also weathered rather well.. HTH

Was it me, I'd lay a piece of plywood under the homasote, even with 12" joists. 1/4" ply is stiffer that Homasote is ever gonna be.

David Starr

Shellac is cheap, covers well and dries before the dust has time to settle in it and wreck the finish. Makes a good primer under just about anything. The solvent (alcohol) will dissolve dried shellac so if you forget to clean the brush all is not lost. The alcohol makes a fair track cleaner (Goo gone is better). Shellac doesn't keep well in the can. If the can is more than a few months old, it's better to pitch it and buy a new one for any work you care about. On good wood, a couple a coats of shellac followed up with a coat of Butcher's wax to water proof it will last a long time anywhere except as a bar top. I have a nice desk chair I refinished in shellac and wax many years ago and it still looks first rate.

David Starr

Absolutely. Un-supported homasote is a bad idea. 1/2" ply seems to be the standard. I have always used 5/8".

-John