Topics

Galvanized roofs


Brian Shumaker
 

A recent post on another forum discussed weathering of steel boxcar roofs and I queried if all cars had galvanized roofs. Why, does it seem, some cars shed their roof top paint and others didn't?  Did some car makers use galvanized panels while others did not?
Brian


John Sykes III
 

Yes.  Some did and some didn't.  Some paints would not stick to galvanized steel at first, so early roofs almost always had their paint peeling off, sometimes dramatically.  Eventually steel manufacturers came up with galvanizing processes that were more "friendly" to paint and paint manufacturers came up with paints that stuck to galvanized panels better.  Eventually, many carbuilders just left the galvanized roofs unpainted.

-- John


Craig Wilson
 

And . . . it was common (in the era covered by this list) to coat the roof (and ends and underbody) with black "car cement" to prevent leakage.  This car cement was also prone to peeling off and sometimes was painted over if the car was repainted.  All this is responsible for the wide variety of weathering/coloring on the roofs of these cars for the modeler to ponder and replicate.

And . . . I was told once years ago that the peeling effect was more prominent at the ends and middle (doorways) of the cars.  This is because there was more likely to be empty space above the cargo at these locations thus greater heat build-up there.

Craig Wilson


Schuyler Larrabee
 

I think the greater prominence of peeling in those locations is that the car (and therefore the roof) flexes more at those points, and the “working” of the joints tends to crack whatever protective coating, car cement, paint, galvanizing, whatever, which permits the enemy, water, to penetrate to the victim, steel.

 

Schuyler

 

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Craig Wilson
Sent: Friday, August 14, 2020 10:26 AM
To: main@realstmfc.groups.io
Subject: Re: [RealSTMFC] Galvanized roofs

 

And . . . it was common (in the era covered by this list) to coat the roof (and ends and underbody) with black "car cement" to prevent leakage.  This car cement was also prone to peeling off and sometimes was painted over if the car was repainted.  All this is responsible for the wide variety of weathering/coloring on the roofs of these cars for the modeler to ponder and replicate.

 

And . . . I was told once years ago that the peeling effect was more prominent at the ends and middle (doorways) of the cars.  This is because there was more likely to be empty space above the cargo at these locations thus greater heat build-up there.

 

Craig Wilson


Brian Carlson
 

In the steam era though you didn’t see massive amounts of peeling paint. At least not in the photos I’ve looked at. 

Brian J. Carlson 

On Aug 14, 2020, at 8:37 AM, John Sykes III via groups.io <johnsykesiii@...> wrote:

Yes.  Some did and some didn't.  Some paints would not stick to galvanized steel at first, so early roofs almost always had their paint peeling off, sometimes dramatically.  Eventually steel manufacturers came up with galvanizing processes that were more "friendly" to paint and paint manufacturers came up with paints that stuck to galvanized panels better.  Eventually, many carbuilders just left the galvanized roofs unpainted.

-- John


Mont Switzer
 

I have made the same observation as Brian.  All steam era roofs seemed dark.  I always attributed this to steam locomotive exhaust soot. 

As diesels took over freight cars seemed to stay cleaner and even brighter.  No soot.  Improvements in paint certainly helped this also.

Mont Switzer 



Sent from my Verizon, Samsung Galaxy smartphone


-------- Original message --------
From: "Brian Carlson via groups.io" <prrk41361@...>
Date: 8/14/20 10:32 AM (GMT-05:00)
To: main@realstmfc.groups.io
Subject: Re: [RealSTMFC] Galvanized roofs

In the steam era though you didn’t see massive amounts of peeling paint. At least not in the photos I’ve looked at. 

Brian J. Carlson 

On Aug 14, 2020, at 8:37 AM, John Sykes III via groups.io <johnsykesiii@...> wrote:

Yes.  Some did and some didn't.  Some paints would not stick to galvanized steel at first, so early roofs almost always had their paint peeling off, sometimes dramatically.  Eventually steel manufacturers came up with galvanizing processes that were more "friendly" to paint and paint manufacturers came up with paints that stuck to galvanized panels better.  Eventually, many carbuilders just left the galvanized roofs unpainted.

-- John


Brian Shumaker
 

From photographs it seems one can almost assume that the all-steel cars probably were built with galvanized roofs and many wood-sided cars and some railroad manufactured cars(PRR, B&O, Milw, etc) may not . It would be interesting and useful for modelers to know which cars were equipped with them.  I'd be annoyed if someone looked at my beautifully weathered car with peeling roof panels tell me that it didn't have a galvanized roof. 
Brian


Tony Thompson
 

Schuyler Larrabee wrote:

I think the greater prominence of peeling in those locations is that the car (and therefore the roof) flexes more at those points, and the “working” of the joints tends to crack whatever protective coating, car cement, paint, galvanizing, whatever, which permits the enemy, water, to penetrate to the victim, steel.

     This is certainly true, though galvanized coatings are not brittle. Note also, though, that galvanizing often fails at sharp corners, for example along the edge of the raised panels in a roof. Paint is thinner there. As Schuyler says, as soon as paint/car cement exposes the galvanized. it is at first protective (that's its purpose) but as more and more galvanized is exposed, eventually a pinhole begins to rust. All downhill from there <g>.

Tony Thompson




Benjamin Hom
 

Brian Shumaker wrote:
"From photographs it seems one can almost assume that the all-steel cars probably were built with galvanized roofs and many wood-sided cars and some railroad manufactured cars (PRR, B&O, Milw, etc) may not . It would be interesting and useful for modelers to know which cars were equipped with them.  I'd be annoyed if someone looked at my beautifully weathered car with peeling roof panels tell me that it didn't have a galvanized roof."

Or you can model from those same photos instead of trying to guess.


Ben Hom


Schuyler Larrabee
 

Tony, whether they are “brittle” or not depends at some level on how thick the galvanizing was applied.  I have seen galvanizing that would sheet off in large flakes, sometimes all the way down to the bare steel.  And in a case like that, the working of the joints as the car and roof were flexed would wear though the galvanizing.

 

I know you’re an expert in materials, but a metallurgist once told me that once rust starts, you’re screwed (his term) because even if you get most of it, even what appears to be ALL of it off, once it’s started you simply cannot stop it without extreme measures.

 

Schuyler

 

Schuyler Larrabee wrote:

 

I think the greater prominence of peeling in those locations is that the car (and therefore the roof) flexes more at those points, and the “working” of the joints tends to crack whatever protective coating, car cement, paint, galvanizing, whatever, which permits the enemy, water, to penetrate to the victim, steel.

 

     This is certainly true, though galvanized coatings are not brittle. Note also, though, that galvanizing often fails at sharp corners, for example along the edge of the raised panels in a roof. Paint is thinner there. As Schuyler says, as soon as paint/car cement exposes the galvanized. it is at first protective (that's its purpose) but as more and more galvanized is exposed, eventually a pinhole begins to rust. All downhill from there <g>.

 

Tony Thompson

 

 

 


Tony Thompson
 

Schuyler Larrabee wrote:

I know you’re an expert in materials, but a metallurgist once told me that once rust starts, you’re screwed (his term) because even if you get most of it, even what appears to be ALL of it off, once it’s started you simply cannot stop it without extreme measures.

     True, unless you can seal the rust area so no more moisture gets to it (this is never 100 percent successful). But keep in mind that not being able to stop rusting, but stretching out the problem past the economic life of whatever is rusting, is still a win.

Tony Thompson




np328
 

    I will look for the letters I read the following information from however as Richard Hendrickson used to say at the start of his presentations "to put all this in context". 
Context: The NP built 1000 boxcars for on-line needs in the first half of the fifties that once loaded promptly went off-line and stayed that way for several years. (Why you need to model NP boxcars).  I would like to do a presentation/article on these as routing on five cars through two years was provided and those cars did get around the US and even into east and western Canada. 
   
    In the letters were a survey of the condition of the cars several years after building once a few came back and I do recall words to the effect that some cinder cutting is noted on the the roofing. The word some. No words that paint failure was noted to any large degree which would back up the observations of BC and SL, or that these cars needed to be shopped for repair/repainting. 

     Of roofs being sooty, I seem to recall several times Richard Hendrickson admonished us in presentations that during the steam era cars were sootier than many of us ever model. Photos of Richard's modeled cars back up that he modeled as he stated. Jack Delano photos of the cars seen in the downtown IC Chicago yard area by my prior recent postings underscored this also. And do not show severe flaking or failure of roof paint.  

         Please recall also that on most cars less than 20 years old - the railroad does not own these, the trust that funded the purchase of these cars does. And the railroad needs to keep up these cars to some minimal standards agreed to in the original contract that these were purchased under. Perhaps your studied railroad bought equipment outright with cash however for much of the history of what I have read, my studied railroad these car were purchase through bonds, hence the trust plates on the boxcars in builders photos. I'll see if I can find the paperwork that notes - cars painted under trust agreements - or something to those words.  It is a sizeable group each year in shop records.

So I would petition that this negates to some degree extreme paint failure modeling.

                 At the end years of the STMFC stated time frame, and when some railroads were teetering financially, perhaps an argument can be made to differ. 
                                                                                                                                                                                                                                           Jim Dick - St. Paul, MN 

   


Dennis Storzek
 

I have always wondered if it wasn't an issue with the paints in use during different periods. During the era before WWI and 'tween the wars, the common freightcar paint was some sort of cheap pigment (almost always iron oxide based) in linseed oil, a naturally polymerizing oil. Linseed oil leaves a lot to be desired as paint, it's a potential fire hazard, takes forever to dry, and stays soft for a while even when dry to the touch. But it does form a tough flexible film that sticks tenaciously.

Beginning just before WWII synthetic alkyd enamels became popular. These solved many of the application problems inherent with linseed oil, and the other popular freightcar coating, asphalt based car cement, but perhaps at the cost of lesser adhesion, and that is when peeling roofs became more common. Remember, the railroads weren't looking for the BEST freightcar coating, only the most cost effective. That still holds true today, or freightcars would be painted with Imron. Given the reduced application costs, and the fact that "nobody sees the roofs, anyway", the railroads just made a judgement as to what was sufficient for their needs, eventually deciding that it was a waste of time to paint roofs at all, but somewhat after our period of interest.

Dennis Storzek


Tony Thompson
 

Dennis Storzek wrote:

I have always wondered if it wasn't an issue with the paints in use during different periods. During the era before WWI and 'tween the wars, the common freightcar paint was some sort of cheap pigment (almost always iron oxide based) in linseed oil, a naturally polymerizing oil. Linseed oil leaves a lot to be desired as paint, it's a potential fire hazard, takes forever to dry, and stays soft for a while even when dry to the touch. But it does form a tough flexible film that sticks tenaciously.

  Certainly all true, but perhaps oversimplified. I was intrigued, reading issue after issue of _Railway Age_ in the first years of steel cars (up to World War I), how many articles there were about getting paint to stick to galvanized surfaces. Many, many formulations were suggested, with many claimed as "highly effective," then the claim would soon be contradicted by a car supervisor for some other railroad. They definitely weren't just using "body paint," but were striving to devise formulations to achieve paint adhesion to galvanized.

Tony Thompson




erieblt2
 

Interesting thread. I’ve learned a lot. I had Kalmbach “Freight Cars of the ‘40’s & ‘50’s” handy. The cover is a high angle color shot of a multi-track Chicago yard in 1942. If you have the book check it out. I’m still a bit unsure of how I’ll choose to weather more of my 1950’s box cars. Bill S


On Aug 14, 2020, at 3:24 PM, Tony Thompson <tony@...> wrote:


Dennis Storzek wrote:

I have always wondered if it wasn't an issue with the paints in use during different periods. During the era before WWI and 'tween the wars, the common freightcar paint was some sort of cheap pigment (almost always iron oxide based) in linseed oil, a naturally polymerizing oil. Linseed oil leaves a lot to be desired as paint, it's a potential fire hazard, takes forever to dry, and stays soft for a while even when dry to the touch. But it does form a tough flexible film that sticks tenaciously.

  Certainly all true, but perhaps oversimplified. I was intrigued, reading issue after issue of _Railway Age_ in the first years of steel cars (up to World War I), how many articles there were about getting paint to stick to galvanized surfaces. Many, many formulations were suggested, with many claimed as "highly effective," then the claim would soon be contradicted by a car supervisor for some other railroad. They definitely weren't just using "body paint," but were striving to devise formulations to achieve paint adhesion to galvanized.

Tony Thompson