Almost thirty years ago (where does time go?) when I was doing car restoration work at the Illinois Railway Museum, we used to joke about obtaining lumber that was totally infused with plastic, so as to be entirely waterproof. In the intervening years IRM has spent countless dollars to build buildings to keep the equipment inside, and so the emphasis there has shifted to using original materials, and rightfully so. However, we can all think of instances where preserved equipment is not likely to be stored inside, and it would seem that the use of such a material would have merit.

Well, America's insatiable appetite for wood products, and the environmentalist's insistence on finding ways to recycle various materials out of our waste stream have converged to give us a partial solution; "plastic lumber". Not just any plastic lumber, but specifically Trex:
http://trex.com/

Disclaimer: I have no commercial interest in Trex.

I first became aware of Trex when I was building a screened in deck about eight years ago. I was looking for a decking material that wouldn't warp, split, or rot, because the thought of having to replace the deck under the enclosure walls at some point in the future was just too painful to contemplate. At the time the material was available in only one or two sizes, all with a rough finish. In the intervening years the line has grown in sizes, colors, and surface finish options to the point where I see some possible uses in replication work.

Trex is NOT a foamed product; it is solid entirely through the cross section. It is made by extruding reclaimed polyethylene (from grocery bags and pallet wrap) filled with sawdust. The maker's claim is that the plastic totally impregnates the wood fibers, thereby protecting them from decay, while the wood provides UV shielding and gives some stiffness to the plastic. I can't say about the UV shielding, but edges I rounded over with a router eight years ago are still as smooth as the day I did them; no grain has raised, so no water is getting absorbed by the wood component. According to information presented on the web site, Trex contains no hazardous material, and scraps are not considered hazardous waste, this in contrast to almost any treated lumber.

Trex is going to have some disadvantages. The biggest is that it does not have anywhere near the stiffness of real lumber, and cannot be used as a structural material. A second is that it is heavy, with a specific gravity of .95 or so, it is between 1 1/2 and two times the weight of normal car building woods. On the flip side, its hardness makes it feel like fine grained White Oak, and it can easily be worked with standard wood working tools, although carbide cutters are recommended for power tools. Cost wise, eight years ago it priced between CCA treated Yellow Pine and clear Redwood, so it likely is on par with what select hardwoods would cost.

Below I will outline some applications I think would make sense. I'll point out the design issues I see, and note those things for which there is, at the moment, no answer. If anyone has used this material, or gives it a try based on this recommendation, I would certainly like to see an account of their experiences posted here.

RUNNING BOARDS AND PLATFORMS

There are numerous restored freight cars and cabooses that have never had their running boards re-applied, and the cars simply don't look finished. Why? Simply because no one expects any lumber mounted on the roof to last as long as the steel or rubber roof that was applied to protect the car. I personally feel that attached with stainless steel fasteners and bedded in a good grade of elastomer caulking compound, the Trex parts should last as long as the rubber roofing beneath them. Trex also looks like it could be useful for caboose platform decking. The original rough surface material would be excellent for this.

One problem is Trex comes with a rather large radius at the corners, but this may not be all that noticeable twelve feet off the ground. The bigger problem is that many cars have saddle spacing greater than the recommended maximum span, which is 16" for 5/4 Trex and 24" for 1 1/2" Trex to provide a 100 PSF loading. We seldom actually have anyone walk on these parts, however, so I'm not sure how much of a loading we really need. The recommended spacing for stickers when piling Trex is 24", but I suspect this is conservative. The only way to find out if this material will sag over time on longer spans would be for someone to try it.

TACK MOLDING

Even on a steel bodied car that has been given a rubber roof over its wood roof sheathing, there is one thin line of wood still exposed to the weather; the drip edge of the tack molding. I belive that Trex would be an excellent material for tack moldings, and most moldings could be milled efficiently from one of the stock sizes. The material's inherent flexibility would be a plus in this application, making it easy to bend the molding to match rounded car ends.

My one concern is that while the material seems to accept standard blue steel tacks nicely (I tried some) the fact that it is a solid material with a different coefficient of thermal expansion than the tacks, which are tapered, may mean that cold creep will cause the tracks to loosen with time. Steel tacks are also not going to have anywhere near the life of either the Trex or the rubber, but the Trex is too hard to take copper tacks. Stainless steel tacks would be one option, if they can be had, or else the short ring shank cadmium coated nails I found in the Mc Master Carr catalog would do the job.

SASH AND DOORS

There is really no reason why this material couldn't be worked into replica sash and doors, for either cars or locomotive cabs, that would have a life expectancy many times that of wood. Mortises would need to be milled; this material is too dense to even think about using a hollow chisel mortiser. Finding an adhesive that holds reliably over time is the challenge, although pinning the mortises with either stainless steel screws or dowel pins would ensure that the joints stay together. Interior finish could not be a natural wood, of course, but this isn't a problem on may pieces of equipment that this material would be considered for.

CAR SIDING AND ROOF SHEATHING

Trex would be an excellent material for replicating a double layer board roof of the type quite common on freight equipment and cabooses built around 1900. These are almost never restored in kind, because the water that gets trapped between the two layers of sheathing assures a very limited life. Using Trex, the inner layer of boards could be real wood for strength, covered with a rubber membrane to exclude water; this in turn could be covered with a layer of Trex "boards" for authentic appearance. Bedded in elastomer and attached with stainless screws, these would have as long a life expectancy as a rubber roof.

Car siding is another application that may be viable. Having to custom mill this much material may be expensive, but I note with interest that Trex offers custom extrusion on their web site. I have no idea of cost, minimum run size, or even if they can extrude profiles with sharp enough corners and adequate precision in the tongue and groove, but the idea is intriguing.

To sum up, I can see how, given sufficient budget, this material could cover every exterior surface of a restored car that had, by necessity, to spend its life outside in the weather. Proper design and sealing of the Trex "skin" would then keep water from attacking the framing, which could be made of conventional materials. Better yet, with proper attention to details, the Trex exterior could be made indistinguishable from the original painted woodwork, so little authenticity would be lost.

We use epoxy consolidents and fillers, would consider engineered lumber (Plywood or Glue-lams, but so far don’t think that the “Plasticâ€

Plastic ties are also available. They can be specified for environmentally critical areas where creosote contamination of water might be an issue (at least in the opinion of the regulators..)

Randy,

Not wanting to be argumentive, but I feel compelled to respond. You didn't say whether the ADA ramp was constructed from Trex or one of the foamed products, which I admit are not suitable for any use on railroad equipment. I need to point out, however, that building a ramp that people will actually walk on brings with it the requirement of providing a suitable floor loading factor. The 16" and 24" max.spans I cited provide a 100 Pound per Square Foot loading, which is suitable for residential use. Commercial use, such as your ADA ramp, likely require 200 PSF load factors, which drop the usable spans to 12" for the 5/4 stock, and 16" for the 6/4 stock. This appears to be in line with what you discovered.

But, with only one exception, the uses I suggested were not for horizontal use, and the one that was, running boards, is an item which is never likely to be walked upon. The typical alternative I've observed is to simply omit them, leaving the roof line of the car woefully incomplete. I'd rather have the boards replicated, even if they do sag a bit in time, than have the brackets standing there empty.

Other uses are split between applications where the Trex would be continuously supported, such as tack moldings and the top layer of a double layer roof, and vertical applications. I will admit that building doors of Trex for an operating passenger car may not be suitable, as they may flap like sails in the breeze as the car runs. Then again, building doors and sash for the cab of a locomotive displayed outdoors in a park may allow them to last for thirty, forty or more years, while still being able to resist the occasional rock that bounces off the Lexan glazing. It is simply a matter of making the proper choice of materials for the display situation.

And that is the crux of the matter. This material may be too far from the proper look and feel to be used at all on operating equipment, although, if the D&RGW can build narrow gauge coaches with steel sides, that may not be true. There are, however, many other instances where it would be entirely suitable. As an example, I was out at Jamestown at the Sierra Railroad a couple of weeks ago. The Sierra facilities are a virtual time warp, and the scene is framed by the row of old boxcars that have been sitting on the shop lead since the Sierra quit using the facility ages ago. To preserve the cars, these need to go inside, but to preserve the SCENE, they need to stay right where they are, outside in the weather. Which is the proper course of action, restore them at great expense, using traditional materials so they can rot away in twenty or thirty years, or substitute some surplus fifty foot steel boxcars that will be cheap to maintain? I'm simply proposing a way to get more bang for the buck while still allowing replication of the older style equipment.

randy,

i will put my oar in on this question.

The highest form of historic preservation is replacement in kind. And any of the synthetic materials that try to look like wood planks simply do not make it in ans asthetic sence or a longer term.

I know of one ship where plastic planks were put down and the owner sued the manufacturer for making false claims as to how well the stuff would stand up to the weather.


The use of the real thing can be extended by using preservatives and lots of good old fashioned oil base paint.

Also remember that rail cars all had their share of repairs during their working like.

Even more repairs went into ships or they would sink on you!

Ted Miles

Dennis,

The only reason I'm replying to this thread is because I get to TREX's plant at Fernley, NV from time to time. Being onsite, and in the stacks, its nothing like being in a lumber mill's drying yard/storage yard.

For decking, I can see some good cost benefits to the material. On their web site I read about working the material for decking. I can see it being used to deck, seat and rail an excursion flat car. I can also envision its use for decking around a depot structure. Yes recreating wooden sidewalks too.

Maybe, I didn't go deep enough into Trex's web site to find more information on working this material into other stock, such as window sash, door stock or molding.

Trex's material seems to work out OK for decking, but can it be worked into other stocks as easily as say a ponderosa pine board?

I'm not a carpenter, lumberman or lumber remanufacture, but again I ask; can these basic deck sized pieces be reworked into other stock? Can this stuff be milled?

If Trex's material can be reworked into other stock, I say use it for operating equipment that is held for operation and not held for historical reasons.

Jim

Which brings us back to the original discussion on wood car rot. From that discussion, it becomes clear that:

1) Replacement in kind is often not possible because the original material is no longer obtainable. Substitution of plywood, glue lams, or wood of a different species is still substitution.

2) Each year there are fewer preservatives are available to us. Thirty years ago, everything got a bath in Penta before it was installed. Now we're limited to water soluble Boron compounds.

3) When is the last time anyone saw good paint? The oils are still available, but White Lead is unobtainable. Commercial paint formulators have gone from concerning themselves chiefly with coating performance to co concerning themselves with government regulations, and performance is now a distant second.

I am curious about the comments about a lawsuit over plastic lumber failure. What brand/type of lumber? Was the failure strictly appearance (like it faded the wrong color) or was it diminished physical properties? How long did the failure take?

Well, of course it isn't, because it's not lumber. But, then again, much displayed railroad equipment is not displayed in a anything near a service environment. Few railroad cars were designed with the idea that they would sit out in the weather for eternity without either moving to shake the water out, or heat to dry them. Those that have tend to end up like the Northern Electric boxcars someone posted a picture of.

Replacement in kind is of course the gold standard of restoration, but that needs to go hand in hand with the gold standard of museum display; indoor storage in a climate controlled facility. Doing replacement in kind restorations only to let the equipment sit outside just slows the mushrooms down. I am of the opinion that using long lasting substitute materials once, when the original construction can be studied and replicated, is preferable to doing the same restoration over and over again, each time losing more of the original construction details.

There is no information about milling Trex on the web site; it is a use they don't envision. That is exactly the reason I started this discussion in the first place, to challenge people to think outside the box. Neither plastic pipe manufacturers nor foam insulation producers envision their material as boiler lagging, either, but both work very well in the context of an engine that is on static display.

In my life, I've gone from being a carpenter, working wood, to a tool designer and toolmaker, working tool steels. I'm of the opinion that if you can cut it, you can work it; you just need to figure out how. My little hands-on experience left me with the impression that the material will work like hard maple or oak; hard and dense, but cutting cleanly with sharp tools. It certainly cut easily enough with a Skilsaw, and my crappy Craftsman router handled it OK. I would suspect that it will power feed through a shaper just fine, once the optimum feed speed is determined. I am a little concerned about power feed planers; a wide cut is going to take a lot of horsepower, and I'm not sure the surface will allow the feed rollers to drive the material against it. As with all plastics, carbide cutters are a must. Unfortunately, I have neither the time nor shop equipment to put any of this to the test; I'll leave that for others.

Like you Dennis, I think Why Not?

Sure, not for casual replacement of original fabric in conserved artifacts, but if it can help reduce or slow future loss in stuff left to rot outdoors and free up more resources it seems worth pursuing.

Of course, I am preparing to experiment lining crossheads with MDS impregnated nylon so a bit of retrofitting for practicality in objects in the use or disposable collection doesn't bother me.

Carbide tools and probably a light feed? Melting plastic gumming up the cut would be my concern.

dave

Dave,

Sounds like you have need of some carbide tooling yourself. While the MDS filled Nylon feels soft, it will quickly hone the cutting edge right off of saw blades.

Back when I was working as a carpenter, I worked in a shop that cut a good amount of 1/4" sheet plastic for glazing, both acrylic (Plexiglass) and polycarbonate (Lexan). Melting was never a problem, so long as the blades had adequate clearance ground on the teeth. Those carbide "planer" blades with the really big carbides ground parallel on the sides with no clearance were not the most suitable for this work. Basically, any blade or cutter that burns the work while cutting wood is going to have problems with plastic products.

When I worked the Trex, I did all the cutting with a Skil saw equipped with a so called "nail blade" (small little carbide tips meant to eat an occasional nail) and it worked fine. For shop work, I'd peruse the specialty blade catalogs to find a table saw blade with some clearance ground on the sides. The router bit I used was a run of the mill carbide 1/2" rounding over bit that fit a ball bearing pilot; that's a reasonably big bit for a 1/4" shank. If I were equipping myself to work this stuff all the time, I'd move up to a bigger router with a 1/2" collet. As it was the Trex cut surprisingly clean. I think the wood particles served to abrade any plastic build-up off the cutting tools.