Seen on home shows, exterior trim made of pre-primed PVC(?). Mills like wood, paints like wood nails like wood, lasts forever. Has anyone used it on wooden cars, cabooses, cabs? Yes, I know, not authentic, but leaving that aaside......

Glad you had the guts to ask this question, I have been afraid of getting flamed to death by just asking. I too have seen this type of material being used for decks and othe outside uses. It seems to worthy of at least looking at. One does get sick of seeing car siding only last a few years outside. If your lucky to have a roof over your equipment that might not be a problem, but for equipment that is outside is sure is. May not be the answer for serious restorations, but a great question in my book. Sort of like looking into using nylatron for hub liners, not a wrong approach, just a different approach. Cheers, John.

I think PVC a great idea for preservation. In a perfect world, sticking with the original material is ideal, but railroads were practical and used what was available, what worked for the application, and ultimately made them money. My concern would be how it survives at low tempertures where there is movement. What is plyable at 70 deg. may not do so well at 10 deg. I have run wooden trolley cars on cold winter nights and even on good track, they can flex like caterpillars.

As we well know, finances play a huge part in the survival of a museum. Getting the best bang for the buck is what matters right after safety. Most people that come and pay their two bits come to see the "choo choo". They couldn't care less what the material is that the car was built of. Many musuem types live in thier own worlds and forget this. Don't get me wrong, accuracy is important as back in the day it was done a certian way for a reason, but I doubt PVC and other polymers didn't exist in the '20's like we have today.

Ah, Plastics, a subject that's dear to my heart. I've written here previously about "Trex" a composite wood / plastic decking material that I think has great promise, but I'm not so sure about extruded PVC.

The extruded PVC building products I’m familiar with, and I’ve used both brick mould and 1X6 fascia boards, are not going to be very useful for car restoration work. Each was an extrusion of relatively high density foam, with a solid skin on the outside of the profile, but still foam, and any cuts exposed the porous center to the weather. In addition, to hold some sort of dimensional stability, the profiles were modified with big grooves on the backside; the brick mould had one central groove that turned the section into a “C”, while the “1X6” had a series of half inch X half inch grooves on one inch centers all across the back. Neither section had any stiffness beyond what one would expect from a strand of wet spaghetti. I just don’t see any application in car restoration work for this material.

Trex, http://www.trex.com is a different story entirely. A mixture of real wood sawdust and recycled pallet wrap, the wood fibers give the material stiffness, density, and UV resistance, while the plastic resin makes it impervious to water. I’ve had this material on a deck for over ten years now, and it looks exactly the same as the day I installed it.

Trex is solid, not foam, and the pressure of extrusion forces the plastic resin entirely into the pores of the wood, which doesn’t swell, splinter, or powder off, even in areas that have been cut or machined. Working it feels like working dense White Oak, and carbide cutters are recommended. The biggest disadvantage is the standard sections come with a generous 3/8” radius on the corners, which makes extrusion easier.

I can see several obvious applications for this material. The first is running boards on restored freight cars. Typically people who restore freight cars and cabooses leave the running boards off; the roof was so much work, and they just know that the boards that mount on top will rot away long before the rubber roof membrane will. I suggest that the Trex composite material will have about the same sixty year service life claimed for EDPM rubber membranes, and so there is no reason not to complete the restoration. Be sure to use stainless steel fasteners, as with service lives this long, steel fasteners will rust through long before the components themselves fail.

I could also see milling the top, or both layers of a double board roof from Trex, so historically accurate roofs could be fitted to period cars, rather than covering the roofs with sheet metal or rubber. A two layer roof with the rubber membrane in between the layers should remain watertight for decades.

I could also see Trex being used to replicate the millwork that goes into the cab of a displayed steam locomotive; the sash, doors, and interior lining of the cab. While the material may be modern, the joinery would be entirely authentic, and once painted, would look more historically accurate than any other replication technique, and certainly more authentic than the rotten millwork many park engines display.

Potential pitfalls and problems? Well, Trex isn’t as stiff as real wood, and the span tables will seem to preclude its use for running boards. However, for non functional running boards, where springiness shouldn’t be a problem, my gut feeling is 1 ¼” Trex will work on a 36” span and not develop a sag over time, but the only way to tell is for someone to try it. Likewise, I have no idea how well paint will stick to Trex, although today’s paints don’t stick to anything particularly well, so why should Trex be the exception? And finally, someone will have to do the research to find a glue that works for building millwork with Trex. I would just pin all the mortise and tendon joints with stainless steel pins for safety in case the glue line lets go.

I personally think that this would be the perfect material for pieces that need to remain outdoors permanently, and would be interested to hear the experiences of anyone who has tried it.

Railroad preservation, yeah, yeah, yeah. Who can name the film from which his title phrase was garnered? Hint: "Elaine!"

"The Graduate," 1968, starring Dusting Hoffman & Ann Bancroft.

I used quite a bit of Trex on the passenger cars that were made for the new operator of the Georgetown loop Railroad (converted Rio Grande narrow gauge freight cars) We used Trex for the seats, top caps on the open side walls of the boxcars as well as the tack boards (boards that the roof nails to along the top of the car) on the boxcars. Thus far after two seasons of service and two + years of outdoor storage the Trex is holdong up very well, it seems to hold paint as well as or better than wood. The cars operate daily in temperatures ranging from 90+ to below freezing and the Trex seems to do okay with the constant twisting and flexing of an ancient, operating wood railroad car.

I also used trex for the window sills on a Rio Grande narrow gauge outfit car and even used it to make one of the windows, so far it too is holding up well.

The only downside I see to Trex is its cost and that it tends to eat saw blades when you work with it. It would be interesting to see if you could mill siding out of it, though I'm sure the cost of such an experiment will prevent anyone from trying it.

Jason Midyette

It will be interesting to see how this stuff holds up...

I have seen some deck installations with a lot of warp and sag, possibly because they ignored the directions for spacing supports and used the larger spacing you'd typically use with wood.

The other potential issue is UV (ultra-violet light) resistance. Not sure how this stuff is, but some plastic materials turn to crumbs after a few years in direct sunlight. I also don't know if paint will reduce the problem.

Anyone know details on the UV issue?

One of the things we need to be careful with is defining what we are talking about. I just did a quick Google search on "plastic deck boards" and came up with "Forever deck" plastic lumber. This product claims to be recycled HDPE (High Density Poly Ethylene). The engineering specs. show a specific gravity of .685. Since solid HDPE has a specific gravity of .96 - .97, this has to be an extruded foam product, which are not noted for any sort of strength or dimensional stability.

The material both Jason and I are talking about is Trex, which may be in a class of its own, due to being a patented process. This material is best described as plastic COMPOSITE lumber, as it is a mixture of natural wood sawdust bound together with about 50% recycled resin. It generally looks like wood, except it has no grain. It's heavy, Trex spec.s claim a SG of .91 - .95, equal to the densest White Oak. I've had this material on my deck for close to ten years now in northern Illinois, and it is essentially unchanged. The Trex web site claims that their accelerated weathering tests are up to about the equivalent of fifty years of weather exposure, with no degradation.

A couple questions and comments for Jason. Window sills would seem to be a natural application for this material, as they tend to fare worse in weathering than siding. I've also thought of tack molding, which would then give the drip edge a service life similar to a rubber membrane roof, but I have one concern. Since the Trex is solid, with no pores to provide any room for material deformation, I wonder if the Trex will eventually push the tapered shanks of the canvas tacks back out? Jason, Have you seen any evidence of this?

Also, was the window you mention made with conventional mortise & tendon joinery? What did you use for glue?

I'm sure that pricing Trex against common lumber will be cause for potential heart failure, but how many of us are using common lumber for restoration work? I seem to recall that Strasburg spent $16,000 for custom milled Honduras Mahagony car siding for a single boxcar, in an attempt to use a material that will be maintenance free for more than a few years. Compared to that figure, Trex might price out well.

Each time I go to the Trex web site I find they have added more profiles. They now have 3/4" material 7.25" and 11.375" wide, so there are now some stock sizes that car siding could be milled from. It's a shame that it can't be the correct 13/16" thick, but neither is anything else other than custom these days. The only thing I can't determine from the web site is what the corner radius is on this 3/4" material, but if the edges are going to be tongued and grooved, this shouldn't be an issue anyway.

And no, I don't own stock in Trex Co. I just think it could be a good solution to getting longer life out of repairs to artifacts that will remain outside in the weather.

At the Campo Depot, the Pacific Southwest Railway Museum used a product called "Broadwalk" to reinstall the loading dock. It's very dense and seems to be holding up well. It's the only product fire rated - it will not burn in a wildfire. Important in the mountains in Campo.

Although I have no first hand experiance with this product, if this is CertainTeed Boardwalk Composite Decking, it appears similar to Trex. See:

http://www.tc-alum.com/patio_boardwalk.html

We have been using a product called Kleer for a little while. We first used it on clerestory panels to replace the MDO which fails prematurely at exposed end grain without epoxy treatment.

We have replaced t&g siding boards on a small scale to see how that works. Our lounge car with fake batt and board siding needed the MDO boards replaced so we will have a car in service with complete sythetic skin below the belt rail.

I hate to do it, but wood today just ain't the wood of yore. Neither are the paints - depending upon the hazard level you can tolerate. Depending upon how this stuff works, I anticipate that we will be using it extensively in non-structural applications.

I believe another product is Azek, but I don't think they have quite the selection of sizes.

Thanks Linn,

Another product I'm not familiar with (introduced into the market in 2005, according to their web site) this may be the product that was originally asked about at the beginning of this discussion. I note that this is a small cell, high density foam product, and that cut edges will show the cell structure, although that shouldn't be much of a problem in applications where most edges are hidden. However, it makes this material unsuitable as a wood substitute for running molding.

I note with interest that they have an extruded beadboard pattern. It would be interesting if someone were to price a custom extrusion die and a custom run of car siding; either the ARA standard 3 1/4" single board or 5 1/4" center V groove patterns would be extremely useful, and who knows, might catch on with the homebuilding market, too.

As Linn says, it isn't wood, but what is available in natural wood these days ain't your grandfather's lumber, either, and most lumber of the grades and species traditionally used for carbuilding are either extremely expensive, or simply unobtainable. I'm of the opinion that I'd rather see the construction techniques preserved and carried forward rather than simply using convenient material; that means separate dressed and matched boards rather than sheets of plywood. If it comes to the point where the boards need to be a substitute material, the fact that they are separate strips rather than huge composite sheets still keeps the restoration closer to authentic.

In the interests of making this thread retrievable and truly useful, I've changed the title to "Plastic Lumber in Restoration" and included a link to the Kleer web site.

http://www.kleerlumber.com/index.jsp

YES. Same product.

For those of you who have been using plastic lumber in restoration projects, how has the material been holding up? I see that some places started using it about a decade ago, so enough time has passed to now be able to ascertain the long term suitability of these materials.