The IRM is in the process of re installing canvas roofs to a few cars. Originally the completed roof would have several coats of a thin black lead based roof paint to the canvas.
I’m curious if anyone out there has a used substitute roof paint without the lead. And how it has held up over the years. This would not include other Elastomeric Roof Coatings, but as close to original as possible, without the lead.

We used multiple coats of marine deck enamel from Pratt & Lambert tinted to the desired fleet color. I recall we cut the first coat with linseed oil.

Wesley

10 years ago, doing a caboose roof, I found that "best practice" called for the use of Linseed Oil based paint.... and we did... In retrospect, I think that any quality exterior paint is ok.. but that a solvent based paint is more likely to saturate the fibers of the "duck" fabric on the room... In the historic record, there seems to be a difference between the coats of paint used on street cars (multiple coats until you get a glossy roof with no canvas texture) and a freight car roof, with 3 or so coats, gloss and texture not a concern.

Canvas roofs were common on wooden ships... so following their practice may help.

Randy

Traditionally in Australia we used "Navy Dressing" - a mix of linseed oil, beeswax, pure soap and yellow ochre colouring on canvas. It didn't last long in the Australian sunshine and quickly turned black from soot. Nowadays for operational vehicles in preservation we're using paint on UV stabilised flexible waterproofing like Emerclad instead of canvas.

The Western Railway Museum recently replaced the canvas roof on Key System 271, the first car in our collection.

Although we had replaced many canvas roofs in the past, we had not purchased canvas stain for several years,
and learned that our supplier had closed.

Original recipe (from a supplier which is closed)
(for four gallons of product):
2 gallons Consolidated Polyurethane Enamel #31-2
1/2-gallon mineral spirits
1/2-gallon raw linseed oil
1 gallon Penetrol

The Consolidated product was not available.
We tried Pettit Polyurethane enamel, but it sealed the canvas pores.

We then tried an oil-based paint to increase fiber penetration and reduce pore clogging.
Fine Paints of Europe Hollandlac satin sign paint (Black) eliminated the pore clogging problem.

We also added an anti-mold additive.

Final recipe (for four gallons of product):

2 gallons Fine Paints of Europe Hollandlac satin sign paint (Black)
1/2-gallon mineral spirits
1/2-gallon raw linseed oil
1 gallon Penetrol
Anti-mold additive

This makes a thin paint which will penetrate the canvas fibers but not seal the pores.

At least two coats are needed.

Cars should be kept under cover as much as possible.

I have had real life experince on buildings using various products that are intended for roofs...roof sealers. You can look at HomeDepot or other building material companies and see plenty of this stuff. It's designed to withstand the wide temperature swings and fill gaps...all things that apply to roofs. I know it isn't pretty but I would try mopping that on (in the summer) to hold the canvas in place and then top coating the canvas with some kind of durable paint.
T7

Hello from Western Australia. Our state government railway network ran a number of ancient timber bodied passenger cars on suburban services until a massive upgrade and electrification in the early 1990's. Many of these cars had canvas roofs and so the expertise required to maintain and renew them lasted until relatively recently within the rail maintenance ranks.

It also triggered the use of more modern products as the traditional adhesives and coatings became harder to source. Rail Heritage WA, of which I am a long serving member, copied what the railways were doing and has been using these procedures and products very successfully on canvas roofs on our preserved cars for nearly 40 years. The following is a summary of what we do:

Preparation - remove all old paint/adhesive material from the existing roof timbers (or sections of metal as it may be). If the timber is obviously very dry and porous, you have the option to apply an undercoat to seal the timbers. If the timbers are cupped or distorted from extended exposure, belt sand them flat (I have been known to apply a planer followed by a belt sander to get the surfaces back to an even curve). If there are obvious holes in the wood, or it has shrunk to the point that fluid could flow easily between the joint/edges/tongue and groove, we stick some paper based masking tape over these problem spots prior to applying adhesive.

Adhesive: we use OIL BASED paint of any type - basically mistints or leftovers - all tipped into a big drum and mixed together, left with the lid off and mixed occasionally to allow it to thicken up.

The canvas is cut to a rough size with excess of a bout a foot or more around each side and then rolled so it can be unrolled from one end of the roof to the other. Pnce lifted onto the roof - the adhesive paint (by now a thick goop) is poured out onto the timbers and liberally spread - we've been known to do this with brooms. The canvas is then rolled out over the freshly poured goop and the process continues the full length of the vehicle. We're not sparing with the quantities of the adhesive - the more the better.

Once the canvas is out over the full entirety of the roof the stretching and pinning is done - many and varied opinions as to the best way to attack this but we generally pin centre at one end - stretch along the centreline and then pin centre at the other end, then down each side at the first end, repeat at the second end. Then work along each side stretching sideways but making sure the pull doesn't take the centreline of the canvas off the centreline of the roof.

Priming: Once the stretch and pinning is done, we are back up on top applying OIL BASED undercoat. This is brushed liberally over the whole roof, allowing the outer surface of the canvas to be sealed. Hopefully lots of the adhesive paint has also absorbed unto the canvas so this can bind with the undercoat. Once the undercoat is on - walk away and let it all dry for a few days.

After everything is fully dried and set - we put on whatever edge battening and trim the excess off the ends and sides and then apply the first topcoat.

Topcoat: We use off-the-shelf WATER-BASED ACRYLIC GLOSS paint which we liberally roll on and brush around fittings or the edge, let it dry and then apply successive coats until there is a good, thick glossy layer on the canvas surface. Acrylic gloss is a latex based based paint which, when thick, forms a good waterproof layer which is pliable and expands/contracts with the weather and also bends with the movement of the car. The elastic properties of this paint avoid the eventual forming of cracks that occur when stiffer products are used which don't bend and stretch with the underlying timber. The other big plus is that you can get it easily tinted to the colour you require.

Maintenance - we find that the topcoat lasts 4-5 years before needing any maintenance if the car is outdoors, and virtually forever if the car is stored undercover. Once a re-coat is due, we give the old surface a good scrub with a stiff broom and a bucket of water and detergent then a good hose off. Once dry we apply a fresh coat of acrylic gloss topcoat, maybe 2.

We have canvas roofs that were applied using this method and these products which date back to 1985 and which are as good today as when first applied, despite having spent extended periods outside. As long as the maintenance is kept up these applications last a long time. Attention needs to be paid to corners and areas around roof fittings and fixtures where water can get underneath or between and start problems. Over time the edgings will also need attention, and the staples/pins securing the canvas perimeter may need renewal. The difference we have here in WA is that we don't have ice and snow to contend with in winter.

Everything we use, apart from the canvas, are domestically purchased products available from our local hardware store. This fact has made the continued use of canvas for roofing viable.

I hope that somebody finds this information useful.