I am looking for advice on painted canvas roofs….

We recently received a 1890’s wooden narrow gauge caboose with a canvas roof… The cupola needs work thanks to a low overpass.

This car has (from an undocumented 1970 restoration) multiple strips of canvas, nailed over a heavy industrial felt, then primed with an aluminum paint, then painted in the finish color.

I have read about canvas roofs over burlap. I assume our felt served that function. I have read about using a single piece of canvas, or alternately having the seams sewn prior to placing the canvas on the roof. (the seams on our roof were not sewn)

I have also read about canvas roofs bedded in a heavy putty, traditionally white lead in linseed oil, today chalk in oil.

I believe but can’t find a reference to canvas stretched over the roof wet, then allowed to dry and shrink before painting with multiple coats of paint, resulting in a hard, shinny almost resin-like roof.

Our car was restored by a ship yard, who may have used techniques found in wooden ship construction.

We also have a horse drawn streetcar with a canvas roof... It seems its a skill I need to learn.

What have other people found?

Our crew successfully covered four roofs with the water on canvas method you describe here. We used a single piece of fabric. The canvas was stretched over the roof using by hanging tie plates from the edge of the fabric at fairly close intervals. Then water was poured on. When we were satisfied with the stretch the canvas was tacked down to the car body and trimmed. This was followed by multiple coats of marine enamel.

Only TARS 678 survives as an example. The others were lost in the fire.



Wesley

Hi,

We've had several canvas's begin to tear several inches above the tacking strip, and I believe this was due, in part, that the installation process, the canvas was stretched over the roof, and tacked down. The canvas was not wet down prior to tacking.

With the added use of water base paints, and the moist weather in our area (the cars are stored out side), over time the canvas's have shrunk, causing these rips, that run parallel with the tacking strip.

We also tried a pond liner between the canvas and the wooden roof. The liner was used to keep any sharp edge from poking through the canvas, much like the burlap might. It was a real pain to drill through mounting the hardware on the roof. The fibers in the liner wrapped around the drill bit. We did find a hole in the canvas later, and the liner kept the water out. It was moist on top, but dry underneath.

So much for good ideas.

Karl J.

Beautiful car Wes - you guys did a great job. Nice to see it finished and out in the sun.

I've done one piece and multiple bits of canvas, some complete reroofings and some patches. I've found it worthwhile to fill and sand the roof so that there are no sharp protrusions before applying whatever membranes you choose to install.

White Lead is like Red Lead - unobtainable. I've had good fortune with the thick gloppy white elastomeric roof coatings readily available from big box home stores in 5 gallon buckets, both as a undercoat into which the canvas can be bedded and stretched, than as a filler energetically painted into the weave of the canvas, than a third application over the filled canvas as a primer. Latex cover coat will adhere readily as the finish color of the roof.

Canvas will require rather frequent maintenance, however - gentle cleaning, and every couple years (depending on storage conditions) recoating. Seamless rubber roofing is a good compromise for cars which will se a lot of service and outdoor storage. UV will kill your roof - not wet weather.

Wet stretching is a fine idea - in my first career in the entertainment industry, we used a lot of canvas stretched onto wooden frames in scenery. Traditional application was gluing with animal glue and tacking, followed by application of sizing to stretch the cloth. If the cloth were applied too tightly, the sizing could pull the frames out of shape of break the wood. When animal glue (thankfully) became obsolete, casein and PVA took its place, and sizing could be accomplished with thinned glue or with corn starch solutions. Water based scene paints could also be used to size while base coating in one step for those quick and dirty jobs.

I don't know if I'd try loose canvas tacked down and tightening with sizing in place on the compound curves common to railway car roofs, however.

Caboose - basic arch roof with no compound curves? Try the elastomeric and see if you are not pleased with the results, Randy. I wouldn't mess with underlayment if you do a nice job with the roof substrate, lay on a thick coat of glop, and stretch the canvas into it while it is still nice and wet. Rollers from the center out towards the egdes will help you stretch it and bed it.

dave

Not to detract from Randy's post, I will eventually need to replace the original canvas roof on my wood burning locomotive. It has a simple arched roof.

Other than tin, are there any other options to provide an original appearance and fire resistance?

Randy,
On the DVRR 5 restoration we used used multiple coats of oil base paint( 3 if memory serves me right) over well sanded wood, pre-shrunk No.8 canvas was stretched over wet paint and the paint allowed to dry. We then applied several more coats of oil based paint with drying time between each coat. The canvas is flat felt seamed in the center because we couldn't get the material wide enough. After 4 years it seems to be OK.
The procedure we used we found in a restoration article that I think came out of Orange Empire.

Having done several canvas roofs that have held up for many years, I don't see the need for all of the weights and stretching unless you have severe curvature such as on the TARS car at National Capital. (By the way... nice looking car, Wes.)

We try to use one piece of canvas if that can be managed, I believe it's #6 cotton duck. Our cars do not have any underlayers, by that I mean that the canvas is tacked along the parameter, directly over the roofing boards. I have heard of some properties using a felt underlayment (Chicago comes to mind), but that was not the case in Baltimore. After the canvas is pulled tight (by hand) and tacked, we coat it with Thompson's water seal. I'm not sure if the Thompson's helps or not, but we figured it couldn't hurt. We used to coat the canvas at this point with a product called "Woodlife" (no longer available).

After drying, we coat the canvas with linseed oil, painted on with a brush. Once that is dry, (sometimes several days in the humid east) we paint it with a linseed oil based paint, cut 50/50 with boiled linseed oil, making sure the paint is worked in good. We do not use water based paints on any of our equipment, in any way. After drying (again) we paint it again, with another coat of thinned linseed oil based paint. Finally, we paint it with straight linseed oil based paint, right from the can.

Some of our roofs have been in service for 25+ years. We do have inside storage, and I'm sure that helps. Take a look here for some photos, I'll try to upload some roof shots. http://www.flickr.com/search/?q=bcpr417

Dave,

Great photos. I visited the Baltimore Streetcar museum last February... its a great collection of surprisingly early cars.

For others... still looking for information on underlayment, felt or other under canvas on a roof. Our roof boards are pretty rough, and seem to have been so historically.

Based on both research and the discussions it appears we may have three different methods...

1) Wet canvas stretched over a smooth wood substrate, then painted (in some cases there may have been a "bedding" of white lead in oil or other thick paint)

2) Canvas bedded in thick puddy (back to the white lead etc...)

3) Canvas over felt or other fibrous underlayment.

In all cases painted... apparently historically with linseed oil paints with extra oil.

While we found nailed seams on our roof this seems to be an exception. Generally a single piece of canvas was used if possible, if not seams were sewn.

This appears to be one of those techniques we are using that needs further documentation to preserve skills...

Randy,