Re: Tarp color


John Stutz
 

On February 13, 2021 8:34 AM Mark Kasprowicz <mark@...> wrote:   What were common tarp colors in the 30's and 40's.
Mark

I think this is a matter of both initial treatment and history of the individual piece of canvas.   As Rick mentioned, raw untreated canvas, typically sailcloth, goes from cream to a grey over time.  Bleached canvas goes from white to grey.  Dyed canvas probably greys more slowly, but still accumulates dust and mud.   Waterproofed canvas in this time frame would have been treated with linseed oil, the binder used in oil paints.  With commercial grade oils, this adds a bit of pale yellow to the canvas, but it also alters the reflective properties, adding a sheen when new, that disappears over time where the the canvas is frequently folded or chafed, and as it weathers toward a grey.  Painted canvas tarps behave similarly.  The painted canvas once used to waterproof passenger car roofs was constantly bombarded by cinders that both erode it and add grey pigment.  Tarred canvas will start black before going to a grey.

The end point grey is partially a matter of UV light darkening the canvas fibers, but mostly one of pigments accumulated from a dusty and dirty environment.  Use outdoors in a steam era railroad environment ensures plenty of smoke exposure, as well as cinder erosion.  Minimal or no ballast on the railroad ensures plentiful exposure to the local dust, and to mud pumped up by poorly bedded ties.  Around railroads there will be frequent exposure to iron dust from brake shoes, which quickly goes to rust.  Rain not only washes off dust and mud, but also washes the finer particles in.  And the covered commodity may make a contribution.  So the basic grey is tinted by a variety of sources. With old canvas, no two pieces are precisely the same shade, and any one may vary over its extent.

The current continental average RR dust/mud/exhaust tint is close to Trailer Train yellow.  Sufficiently so that accumulations can almost completely obscure TT car data fields, without significantly altering the car's body color.  The steam era RR tint was considerably darker, although well short of black, and somewhat redder due to universal use of cast iron brake shoes.  And there will be local variations. For instance, Colorado dust may be greyer than the continental average.

Regarding use of tarps on North American railroads, I am at a loss for examples of such in ordinary train service.  I think their use was limited to extraordinary loads, ones that required protection from weather but were too large to go into a box car.  As such, the tarps were probably regarded as part of the dunnage, intended to be used for the single shipment and then discarded.  Or possibly going to the consignee, as part of the shipment.  I am not aware of any use comparable to the way that British railroads regularly provided company owned tarps to cover open loads, but cannot rule out limited local use.

John Stutz
On February 13, 2021 8:34 AM Mark Kasprowicz <mark@...> wrote:


 What were common tarp colors in the 30's and 40's.

Mark K

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