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Does cork road bed expand and constrict with temputure changes?

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Does cork road bed expand and constrict with temputure changes?
Posted by Red Horse on Friday, October 31, 2008 6:35 AM

Now that the winter is coming I've noticed that I have to reset some of my tracks after being away from the layout for a while.

I have the tracks "spiked" down too the cork roadbed (road bed is glued too plywood base) and I can't seem to see any "play" in the connections when I try too move them with my fingers but when I get back too my layout after it has been sitting I get derailments where I had none in the past running session?

I check the track connections before the derailment spot and always find the tracks slightly separated?

The layout is on a 4 season porch without a heat source at this time, is this what is causing my track movements?

It is getting aggravating having to check and reset sections of track before I can run my trains.

Thanks for any input on this crazy event.

Jess Red Horse.

Please visit my Photobucket pics page. http://photobucket.com/Jesse_Red_Horse_Layout I am the King of my Layout, I can build or destroy the entire city on a whim or I can create a whole new city from scratch , it is good too be the King.
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Posted by Fergmiester on Friday, October 31, 2008 6:40 AM

 Jess

Cork is more affected by humidity. Saying that once you've nailed/glued down the cork it should be stable. Once youve ballasted and set it then you will be fine. There will always be some "wierdness" to the layout on those hot humid days and no it's actually not gremlins.

Fergie

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Posted by lvanhen on Friday, October 31, 2008 6:43 AM

Jess, cork is likely to expand/contract with moisture changes, but not with temperature.  The more likely expansion/contraction would be in the track it'self.  Metal expands & contracts more than wood/cork etc. with temperature changes.  My My 2 cents

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Posted by Driline on Friday, October 31, 2008 7:48 AM

I live in Iowa where the humidity and climate change alot in my basement. I've only noticed my track expanding/contracting, not the cork.

Modeling the Davenport Rock Island & Northwestern 1995 in HO
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Posted by CNJ831 on Friday, October 31, 2008 7:51 AM

Based on decades in the hobby I can say that it is pretty rare that atmospheric conditions will significantly change the size and shape of cork roadbed enough to distort trackwork. It is much more likely to see changes in the trackwork resulting from expansion/contraction of the track itself, or the board on which the track has been laid (warping), when the layout is situated in a sunroom or enclosed porch, probably the worst possible location for a layout due to the large changes in temperature and humidity over the course of a year.

CNJ831 

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Posted by cacole on Friday, October 31, 2008 7:51 AM

This has been discussed many times in the past.  The expansion and contraction is in the wood base, not the track.  Wood expands and contracts with changes in humidity, and the only way to stop it is to seal it on both sides with paint or a wood seal product such as Thompson's Water Seal.

We conducted an experiment before beginning our HO scale club layout to determine exactly how much expansion or contraction there is in nickel silver flex track.  Two pieces of new Atlas code 100 flex track were soldered together.  The length of both rails at room temperature was measured.  The track was then put outside in the mid-July Arizona sunlight for two hours.  The rail got so hot that it couldn't be touched with a bare finger, and a thermometer that could read only as high as 140 degrees burst.  Both rails were again carefully measured.  The track was then placed into a deep freeze overnight.  Another measure was taken.  From a temperature of over 140 degrees to zero, the rail contracted less than 1/64th inch over a six foot length.  So we knew to leave an expansion / contraction gap every six feet on the new layout.  The layout is constructed on hollow core doors, which were sealed on both sides, so we have had no problems even in a building with no central heat or air conditioning.

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Posted by 4merroad4man on Friday, October 31, 2008 7:59 AM

Red Horse

Now that the winter is coming I've noticed that I have to reset some of my tracks after being away from the layout for a while.

I have the tracks "spiked" down too the cork roadbed (road bed is glued too plywood base) and I can't seem to see any "play" in the connections when I try too move them with my fingers but when I get back too my layout after it has been sitting I get derailments where I had none in the past running session?

Spiking the track to glued cork roadbed affords the track more ample opportunity to move with humidity changes.  Securing the track with an adhesive caulk such as PL300 or panel caulk would provide a more secure hold.  Sealing the roadbed and track by painting with an airbrush, using acrylic model paint of the proper color, or a thinned latex paint will help minimize the effects of the humidity.

I check the track connections before the derailment spot and always find the tracks slightly separated?

Trackage which has moved due to humidity will also frequently separate due to the geometry of the situation, i.e., losing an arc.  Kinks can also form, but it is important to understand that, like the prototype, wide temperature swings can also cause minute expansion and contraction of the rails.

The layout is on a 4 season porch without a heat source at this time, is this what is causing my track movements?

Pretty much.  Exposed to the weather like that, you can expect problems year round with not only the track, but the scenery and equipment.

It is getting aggravating having to check and reset sections of track before I can run my trains.

Relay your track and properly secure it, seal your benchwork and substrate, or move the whole shebang indoors or start over with AC or marine plywood.

Thanks for any input on this crazy event.

As was mentioned earlier, wood and substrates will move more rapidly and with greater movement than the model railroad supplies, however cork does absorb moisture, and the "trickle down" of movement of your benchwork will cause the essentially unsecured track to shift as well, even though one might believe that track which essentially floating would remain in place.  The effects of direct contact with shifts in temperature and humidity is such an environment as described can be at best, frustrating, and at worst minimally catastrophic if something rolls off a table edge.

Jess Red Horse.

Serving Los Gatos and The Santa Cruz Mountains with the Legendary Colors of the Espee. "Your train, your train....It's MY train!" Papa Boule to Labische in "The Train"
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Posted by CNJ831 on Friday, October 31, 2008 8:14 AM

cacole

This has been discussed many times in the past.  The expansion and contraction is in the wood base, not the track.  We conducted an experiment before beginning our HO scale club layout to determine exactly how much expansion or contraction there is in nickel silver flex track. From a temperature of over 140 degrees to zero, the rail contracted less than 1/64th inch over a six foot length.  So we knew to leave an expansion / contraction gap every six feet on the new layout. 

While this seemingly minor expansion/contractions figure may seem to some almost insignificant, I saw what can result from not taking it fully into account on a layout.

A number of years ago a friend built a moderated sized HO layout over one winter in an unheated sunroom (this is in upstate NY). He butted and soldered nearly every track joint, leaving only a couple of small expansion joints over the entire layout. The mainline amounted to a couple of hundred feet of NS track and the layout was quite impressive.

The first really warm day in June I got a phone call from this individual to come over and look what had happened to his layout. Entering the sunroom I guess it was in the 90's and the trackwork on the layout was hopelessly kinked in several spots. All those 1/64" had accumulated. Needless to say, he had to do an awful lot of work to get things smoothly operational again.

CNJ831

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Posted by loathar on Friday, October 31, 2008 9:38 AM

lvanhen

Jess, cork is likely to expand/contract with moisture changes, but not with temperature.  The more likely expansion/contraction would be in the track itself.  Metal expands & contracts more than wood/cork etc. with temperature changes.  My My 2 cents

Lou-That's actually not correct. Someone posted a while back the expansion coefficients of wood, cork, plastic and NS rail. The rail only had an expansion of about 1/8" over 100'. The wood and cork are the biggest offenders.
Jesse-Welcome to my world. SUCKS! Don't it?? My layouts been up for 3 years and I'm still dealing with it. The second year was the worst. It seems to have stabilized a bit now. Keeping the temperature and humidity relatively constant is the only thing that will work. Painting and sealing all your bench work when you first build it will help too.

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Posted by selector on Friday, October 31, 2008 11:19 AM

I use a dehumidifier year-round.  It goes weeks without kicking in, and at other times I am emptying the reservoire every second day.  My layout is in the basement, in a finished room with carpeting over bare concrete.

I use latex caulk extensively for all things related to the track. The subroadbed is usually just the wood of the bench or spline.  I then use either cork or vinyl underlay as a roadbed surface, but that is only ever secured with a thin layer of latex caulk to the wood below it for the reason that wood expands and contracts with ambient humidity that changes a lot and stays that way for days at a time.  The track sections are also secured with caulk to the underlay or the cork.  The net result is that I have no creeping gaps and no kinks.  The basement ranges in temps from 15 degrees Celsius to 30 degrees Celsius when I have the wood furnace running.  That appliance rests not 20" from one corner of my layout.

I am convinced that wide swings in temperature are not going to affect tracks that have a gap every 8-10' in the order of 1/16".  NS rail expands 1/4" over 100' with a temperature change of 30 deg F.  Ten gaps over that 100' that are 1/16" wide will more than account for any rail epansion.  The wooden bench, though...that's another thing entirely.  Let the humidity in your layout room change by 30% and leave it for a week...see what happens. Mischief

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Posted by dcfixer on Friday, October 31, 2008 12:49 PM

 What about expansin/contraction of homasote compared to wood, cork and NS track?  Would it be prudent to seal the homasote, too?

Thanks,

DC

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Posted by selector on Friday, October 31, 2008 2:01 PM

Going only by reading over a few years, and not by personal experience, it seems to be split.  I have seen some post that they never bothered and that the homasote behaves well, while others are adamant that you must seal it if you want reliability.  The trouble is, each may be perfectly valid views based on personal experience.  If one person doesn't seal theirs, and uses it in a narrow range of temps and humids, then they would be inclined to state as much.  And the opposite experience would also be validly expressed for those whose product behaved badly when they forgot or didn't know enough and had bad conditions in which to use it.

-Crandell

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Posted by fwright on Sunday, November 2, 2008 11:36 PM

 I'm one of the ones who has not had problems with unsealed Homasote despite moving the layout to a variety of climates with widely varying temperature and humidity combinations.  Those who report issues with expansion and contraction and use Homasote over wood state that the wood has contracted/expanded at least as much as the Homasote.  Which correlates well with information on Homasote's web site.  Look-alike products may not do quite so well.

Factors which may have worked in my favor, preventing problems in my particular case:

- layout was small, either 6ft or 8ft long over its long dimension

- rail was handlaid with no rail joiners.  This meant rail was seldom hard butted to the next section of rail.  And the rail could creep lengthwise through the spikes if absolutely necessary.  Electrical gaps were filled with epoxy glue, so little give there.

- any Homasote joints were butt joints, with the 2 ends pushed together.  Given the slight compressability of the somewhat ragged ends (not sanded smooth), any Homasote movement would have merely compressed the joints.

- the Homasote was glued with yellow glue to the underlying 1/2" plywood, pretty much forcing the Homasote to move with the plywood, and not permitting much movement by itself in either horizontal direction.

- Homasote and plywood were later cut to ribbon roadbed, taking away an extensive mass for expansion and contraction.  The plywood was cut from a single 4x8 sheet without any joints, and had a basic oval shape.

IMHO, each person has enough circumstances where some are just different enough to change the likely outcome.  From my experience with wooden boats, there is no doubt that wood changes substantially with moisture content.  The change is greater across the grain than along it, as the wood fibers expand and contract in diameter with changing moisture content.  In boats, dry wood from dry storage will sink unless the boat is kept pumped out for the several days it takes the wood to swell to its normal size. 

Plywood also expands and contracts with moisture, but not nearly as much as lumber.  The expansion/contraction rates for plywood from humidity extremes are very similar to rail for temperature extremes.

And by the way, paint does not prevent expansion and contraction due to moisture content.  Paint reduces the rate of change of moisture content.  The wood will still change to reflect its environment.  It just takes longer if painted on all sides, often allowing the humidity peaks and valleys to pass before the wood reacts.  A better sealer than paint is shellac or epoxy.  But be careful, wood or plywood sealed on only one side will have a greater tendency to warp because of the now uneven rate of moisture migration.  I've seen wooden and plywood boats destroyed by only fiberglassing the outside, and leaving the inside unpainted and unsealed.

Sorry for the long post - but I've learned a lot of lessons about this subject.

Fred W


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Posted by rrinker on Monday, November 3, 2008 7:21 AM

 Interesting you should mention Homasote, I was just goinf back through some old issues of MR (mid-50's) and foudn one from shortly after they published the first article on using Homasote as roadbed - and it specifically mentions that right from the beginning there were issues with humidity-related expansion and contraction of the Homasote! The solution, said the author of the original story, was to seal it after the humidity went downa nd it was contracted.

 Despite the known issues, somehow it became the absolute material of choice for many years. Wierd.

                          --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by fwright on Monday, November 3, 2008 12:28 PM

(quote) Despite the known issues, somehow it became the absolute material of choice for many years. Wierd.

I don't find it wierd at all. Flex track was not always the near universal track solution it is today. In the '50s and '60s, handlaid track made up a much greater proportion of track than it does now. And if one spikes his track, Homasote is the most preferred roadbed. There are choices second to Homasote, but they are that - second choices.

Homasote expansion and contraction may or may not be an issue, depending on the individual's environment - there are plenty of reports both ways. There are also plenty of reports of cork drying out and crumbling over time, and plenty of reports who have never experienced any such thing. Woodland Scenics roadbed garners its share of negative reports from users, as does Vinylbed.

Each of the common roadbed materials has both advantages and drawbacks. Drawbacks can generally be minimized and advantages maximized by using particular track construction/laying techniques suited for that roadbed material. I find the most sensible approach is to choose one's preferred track construction, and choose the roadbed best suited for that construction method. I find this approach more sensible than trying to spike rail to the ties on top of cork or Woodland Scenics roadbed.

OTOH, if I were using flex or sectional track exclusively, price, availability, and less mess might drive me towards using cork, despite having had it dry out and crumble in the past. Perhaps using white or yellow glue or latex caulk for cork and track fastening, and ballasting fairly soon after laying (more glue) would help seal the cork from drying out.

As was once said, "Model railroading is an intensely personal hobby."

Fred W

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Posted by Capt. Grimek on Monday, November 3, 2008 12:42 PM
Please forgive me asking this question a 2nd time in a separate thread but it seems appropriate to this thread and my search function is not working at all since the forum's format change... I'd like to use a blueprint shop, printed 12" to the foot (life sized) paper track plan, rolled out onto the bench/table top and lay my cork roadbed and track directly over it. On a past thread, some folks thought or experienced success sealing the paper by simply using the traditional diluted glue/ballast method. Some guys in my club have doubts about the paper causing some warping problems years down the road and have me paranoid again! I don't want to use latex caulk but simply nail the track down to the plywood subroadbed through the cork. Do you guys think that sealing the paper and ply together (both sides) with epoxy or varathane is advised and should be a permanent solution or do you all think that the glue/ballast should do the job adequately? I'll use tracing paper or a pommel wheel if need be, but would really like to use my paper pattern if it's safe long term. Thanks again. I'll read up on the forum bugs when I get some time and see if I can get my search function working again-but thought I might get some different folk's insights and experiences on this thread as well as helping the OP (and others) with future expansion of his layout. Thanks!

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Posted by CSXDixieLine on Monday, November 3, 2008 12:46 PM

fwright
... As was once said, "Model railroading is an intensely personal hobby."

Fred W

Fred, Your comment could not be any more true and you posts above clearly expand upon that thought. Well written and very helpful with regards to how roadbed construction should be approached. Jamie

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Posted by Don Gibson on Monday, November 3, 2008 1:49 PM

NOT IF your cork is tabilized (nailed or glued) into place

TRACK can expamd from running and having small gaps (busines sized) every 3-6 feet or so is the cure'; WOOD can absorb moisture, so make sure it is DRY when you buy it...

MOST of this is not noticable on single board 4X8's it's the more adveturess among us when small changes combine.

HOMOSOTE, was once thought.to be the ideal  roadbed.- until you put 2 sheets together. (different thicknesses).OURS is a constant learning experience, and where 'imagination' comes into play, Not eveyman's PERCEPTION is.identical.We don't all march to the same tune.

Don Gibson .............. ________ _______ I I__()____||__| ||||| I / I ((|__|----------| | |||||||||| I ______ I // o--O O O O-----o o OO-------OO ###########################
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Posted by cudaken on Monday, November 3, 2008 7:10 PM

 Jessie, did you use flex track or is it all sectional track? Is all the problems at rail joiner, did you solder the joints? What kind of tempter change are we talking. Is the problem in turns or straights?

 Guess I am just lucky, layout is in the garage. It is heated but I set it low while I am at work, so 40 to 50 is normal when I get home. Takes about a hour to get it up to 72.. Main bench is made of 2 X 4 with 3/4 plywood. Rear section is against a wood garage door and far from the heat so I would guess that section will see 30's. It will soon be 4 years and not a problem yet with buckling.

 When I was new not to long ago, it was common to have derailments at the joiners. I used them over and over and they started to get sloppy. They must be very tight, all most make your fingers bleed when installing them!

 Few things I do you may not.

 Add extra spikes in turns, 18 inch turns more than wider.

 Solder joiners in turns. I don't in straights unless there is a power problem.

 Extra spikes where the track section butt up against each other.

 If you are having a 40 degree swing during a few hours, I will bite on it being the temperature change. It still may be the learning curve we talked about as well. Took me about a year to get where I had a idea how to trouble shoot problems before they happened again and again.

 One last idea, do you have shades in the room? If it is the heat change, sun beating down on the track may have something to do with it.

              Your steel rail brother Ken.

            Do miss talking with you on the phone.

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Posted by rrinker on Monday, November 3, 2008 9:18 PM

fwright

(quote) Despite the known issues, somehow it became the absolute material of choice for many years. Wierd.

I don't find it wierd at all. Flex track was not always the near universal track solution it is today. In the '50s and '60s, handlaid track made up a much greater proportion of track than it does now. And if one spikes his track, Homasote is the most preferred roadbed. There are choices second to Homasote, but they are that - second choices.

Homasote expansion and contraction may or may not be an issue, depending on the individual's environment - there are plenty of reports both ways. There are also plenty of reports of cork drying out and crumbling over time, and plenty of reports who have never experienced any such thing. Woodland Scenics roadbed garners its share of negative reports from users, as does Vinylbed.

Each of the common roadbed materials has both advantages and drawbacks. Drawbacks can generally be minimized and advantages maximized by using particular track construction/laying techniques suited for that roadbed material. I find the most sensible approach is to choose one's preferred track construction, and choose the roadbed best suited for that construction method. I find this approach more sensible than trying to spike rail to the ties on top of cork or Woodland Scenics roadbed.

OTOH, if I were using flex or sectional track exclusively, price, availability, and less mess might drive me towards using cork, despite having had it dry out and crumble in the past. Perhaps using white or yellow glue or latex caulk for cork and track fastening, and ballasting fairly soon after laying (more glue) would help seal the cork from drying out.

As was once said, "Model railroading is an intensely personal hobby."

Fred W

 I suppose it works - but I've used Homasote in the past and was able to easily pull up cork adn flextrack fastened with track nails - I can't imagine spikes holing in place after lots and lots of running - or in particular for turnouts, especially in the days when the only powered option was a fast acting coil machine, either twin coil or rotary. I guess there weren;t many options, Celotex seems popular as well, but I don't know if what we call Celotex today is the same material it was 50+ years ago. And then I guess there was Tru-Scale's roadbed, softwood that take spikes easily but surely was more expensive than bulk sheet goods. People were already using masonite splines but I can;t imagine using any sort of nail or spike to hold things in that. I do recall one article that had you drill holes for evey spike! I suppose if you have unlimited time (and a LOT of paitence...).

 As for cork - I've found a huge variation on cork as far as it drying out. I have some that is maybe 10-15 years old, that lived in a normal 'human' environment. Most of that is brittle and snaps if you try to bend it. Then I have some that has to be 35 years old at LEAST that has lived in an unheated, uninsulated attic for all those years that bends as easily as brand new! It wasn't painted or coated with glue or anything - it's plain unused cork. On the old 'family room' layout we had when I was a kid, nothing was ever glued down, the cork was nailed to the plywood and the track nailed to that. Ballast was spread on loose, and then vacuumed up when it was time to take the layout down. This cork dates from that time but was leftover that never got used. Perhaps like many things, quality was better back then.

                   --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by Red Horse on Saturday, November 8, 2008 9:40 PM

Thanks everyone for the input!

Now that I've added a dehumidifier this problem seems too have gone away?

I have the heater system on the way also.

Sorry I haven't been on the boards much, what little time I do have after working 72 hour weeks and winterizing my home and property I've used my rare free time too run my trains, ahhhhh, I love it when all the hard work pays off.

I added some HO scale ballast too my quarry that is now repainted earth tones, and the scale dirt movers and dump trucks have something too quarry.

I used two bags of ballast (brown) and left it loose so that I can redo the digging scenes and so on in the quarry bottom. (I'll try and post pics of the changes this week).

Hope everyone here is well and enjoying your layouts.

Have a great week!

Please visit my Photobucket pics page. http://photobucket.com/Jesse_Red_Horse_Layout I am the King of my Layout, I can build or destroy the entire city on a whim or I can create a whole new city from scratch , it is good too be the King.

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