Galvanized Paneled Roofs and Modeling Peeling Paint


Bill Welch
 

Using an inaccurate InterMountain paneled roof as a Guinea Pig I am about to experiment with using Rock Salt to create peeling paint, spraying the roof first with a concoction of grey and silver paint. For my trial roof I plan to keep the salt away from the roof ribs since they did not peel (Is "roof ribs" the correct term?).


I wanted to check my thinking however before I apply the salt and BCR paint as to standard or common practice: Am I correct in thinking that the roof ribs were usually not galvanized and common practice was to coat them with Car Cement?


Let me amplify what I am thinking. The ribs may have peeled but because of the car cement, the peeling would not have been as obvious as it was on the galvanized roof panels.


Not very elegant writing but hopefully you get my meaning.


Bill Welch




Guy Wilber
 

Bill wrote:

"For my trial roof I plan to keep the salt away from the roof ribs since they did not peel (Is "roof ribs" the correct term?)."

Seam cap would be the correct term.

Guy Wilber
Reno, Nevada


destorzek@...
 

Ditto. And, all the parts of the roof were galvanized, except the rivets. The seam caps were typically coated with car cement because that's where the potential leaks were; both water creeping under the caps, and water leaking in around the rivets.

Even if they weren't coated with cement, the paint found more nooks and crannies between all the bends and rivets to adhere via the mechanical interface. The paint tended to pop first in the large flat expanses.

Dennis Storzek 


Brian Carlson
 

Years ago someone, Richard I think, cautioned me about doing to much with the peeling paint off galvanized roofs on my steam era cars. He mentioned that yard photos of the steam era don't show the peeling paint effect with the same regularity as the modern era. I don't have as many photos as he did but I've taken his words to heart and have one one peeling paint roof and dozens that are very grimy. Just my thoughts. 

Brian J. Carlson

On Dec 17, 2015, at 1:38 PM, destorzek@... [STMFC] <STMFC@...> wrote:

 

Ditto. And, all the parts of the roof were galvanized, except the rivets. The seam caps were typically coated with car cement because that's where the potential leaks were; both water creeping under the caps, and water leaking in around the rivets.

Even if they weren't coated with cement, the paint found more nooks and crannies between all the bends and rivets to adhere via the mechanical interface. The paint tended to pop first in the large flat expanses.

Dennis Storzek 


Tony Thompson
 

Brian Carlson wrote:

 
Years ago someone, Richard I think, cautioned me about doing to much with the peeling paint off galvanized roofs on my steam era cars. He mentioned that yard photos of the steam era don't show the peeling paint effect with the same regularity as the modern era. I don't have as many photos as he did but I've taken his words to heart and have one one peeling paint roof and dozens that are very grimy. Just my thoughts. 

       Richard did make this point from time to time, and my examination of period photos, up to my modeling year of 1953, agrees entirely. Of course there were cars with roof paint failure, but not a lot, and few with the kind of severe failure one sees nowadays. I model accordingly.

Tony Thompson             Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705         www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, tony@...
Publishers of books on railroad history





Tim O'Connor
 

Bill Welch asked

 >> Is "roof ribs" the correct term?

SEAM CAPS

:-)

Tim


Tim O'Connor
 


Right -- I've always thought the seam caps were either enameled (dipped in
paint and baked) or dipped in some kind of persistent car cement, because even
on extremely peeled roofs the seam caps almost always look still coated. Only
in a few photos of unpainted, galvanized roofs are the seam caps the same
color as the panels.

Tim O'


Ditto. And, all the parts of the roof were galvanized, except the rivets. The seam caps were typically coated with car cement because that's where the potential leaks were; both water creeping under the caps, and water leaking in around the rivets.

Even if they weren't coated with cement, the paint found more nooks and crannies between all the bends and rivets to adhere via the mechanical interface. The paint tended to pop first in the large flat expanses.

Dennis Storzek 


destorzek@...
 




---In STMFC@..., <timboconnor@...> wrote :


Right -- I've always thought the seam caps were either enameled (dipped in
paint and baked) or dipped in some kind of persistent car cement, because even
on extremely peeled roofs the seam caps almost always look still coated. Only
in a few photos of unpainted, galvanized roofs are the seam caps the same
color as the panels.

Tim O'
=============
Pre-coating the seam caps wouldn't work, unless the coating could hold up to the heat of hot riveting, which zinc will. For the same reason, the rivets themselves can't be galvanized, as the zinc coating would burn off while the rivets were in the rivet furnace. So, unless the railroad didn't mind streaks of rust forming under each seam cap, at least the riveted portion needed to be painted or covered with car cement.

I've often wondered why steam era photos show few bare or patchy roofs. It may be that the roofs became dirty so quickly, with the locomotives putting out literally tons of particulates and streaming back over the train, that what we are seeing isn't paint at all, but dirt, and dirt can cover raw galvanized as well as paint.

The change to patchy looking roofs seems to coincide with the general change in motive power.

Dennis Storzek


caboose9792@...
 

 
 
In a message dated 12/18/2015 7:23:23 A.M. Central Standard Time, STMFC@... writes:
Pre-coating the seam caps wouldn't work, unless the coating could hold up to the heat of hot riveting, which zinc will. For the same reason, the rivets themselves can't be galvanized, as the zinc coating would burn off while the rivets were in the rivet furnace. So, unless the railroad didn't mind streaks of rust forming under each seam cap, at least the riveted portion needed to be painted or covered with car cement.

I've often wondered why steam era photos show few bare or patchy roofs. It may be that the roofs became dirty so quickly, with the locomotives putting out literally tons of particulates and streaming back over the train, that what we are seeing isn't paint at all, but dirt, and dirt can cover raw galvanized as well as paint.

The change to patchy looking roofs seems to coincide with the general change in motive power.

Dennis Storzek
I have to agree with you Dennis, if somebody had found a way to make paint stick to a galvanized roof or any other galvanized surface they would have certainly let it be known. Also the galvanizing was not exceptionally thick ether, and those same flat expanses mentioned in your earlier post would lose their coating as did any sharp bends. Furthermore, Those particles streaming back along the train were also notable for being both abrasive and corrosive and coming out of nearly every home business and factory in the country.
 
"Years ago someone, Richard I think, cautioned me about doing to much with the peeling paint off galvanized roofs on my steam era cars. He mentioned that yard photos of the steam era don't show the peeling paint effect with the same regularity as the modern era." its also notable Richard never said the roofs were well painted or painted at all, he just said it didn't show the peeling paint effect.
 
Mark Rickert
 
 


Charles Peck
 



​Or just maybe the old red lead, iron ore and linseed oil really is a superior paint formula after all. 
Chuck Peck in FL​

On Fri, Dec 18, 2015 at 8:23 AM, destorzek@... [STMFC] <STMFC@...> wrote:
 
​  
I've often wondered why steam era photos show few bare or patchy roofs. It may be that the roofs became dirty so quickly, with the locomotives putting out literally tons of particulates and streaming back over the train, that what we are seeing isn't paint at all, but dirt, and dirt can cover raw galvanized as well as paint.

The change to patchy looking roofs seems to coincide with the general change in motive power.

Dennis Storzek



golden1014
 

Hi Bill,


I have used this technique on a few cars and I like the effect.  I don't have any photos available right now, unfortunately. 


I tried it on six roofs at once and I was satisfied with two of the six attempts.  I tried a few with table salt (small granules) and a few with sea salt (larger granules); the table salt provided a much better effect.  The best color combination for the undercoat turned out to be a mixture of light gray with ~20% Testors aluminum mixed in.  Once the salt was removed I painted the seam caps with the original roof color and then weathered the whole roof assembly again with a little black powder to represent soot and dirt.  The addition of a weathered running board really adds to the contrast and overall effect.


Yes, it's my understanding (because Ed has told me this a thousand times) that the seam caps were not galvanized so they would hold paint better.  IMO the artist's objective here is subtle color contrast--contrast between the original roof color, the exposed galvanized surface, the weathered running boards, and the soot/grime overlay--all gently blended together.  


John Golden

Albersbach, DE


destorzek@...
 




---In STMFC@..., <golden1014@...> wrote :

Yes, it's my understanding (because Ed has told me this a thousand times) that the seam caps were not galvanized so they would hold paint better.

============

First I've heard that. The whole roof would hold paint better if it weren't galvanized... but the purpose of galvanizing was to make the steel last, whether it was painted or not. If the caps were not galvanized, they'd be prone to rust out from water trapped between the caps and sheets, and rust out from behind the paint like a modern day automobile. I wonder if the caps were formed from steel sheet that was galvanized on one side only. Seems like a rather deep draw to be cold formed, though. Wish there was some SRECo. literature that explained the production of their roof system.


Dennis Storzek


Tony Thompson
 

Dennis Storzek wrote:

 

I've often wondered why steam era photos show few bare or patchy roofs. It may be that the roofs became dirty so quickly, with the locomotives putting out literally tons of particulates and streaming back over the train, that what we are seeing isn't paint at all, but dirt, and dirt can cover raw galvanized as well as paint.

The change to patchy looking roofs seems to coincide with the general change in motive power.

       This comment has been made before, as to why we don't see the paint failure on steam-era car roofs, and might be true. Real point for modeling is, as long as steam was around, there weren't that many failed roof paint instances.

Tony Thompson             Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705         www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, tony@...
Publishers of books on railroad history





Tim O'Connor
 


Perhaps we can't find information because we call them Seam Caps :-)
(Yes, me too, I've never heard anything else.)

This is what the 1961 Car Builder's Cyclopedia calls them --

ROOF SHEET SPLICE TEE

there is also an item called a

RIDGE CAP

but I'm guessing that ran down the center line of a roof?

Tim O'


First I've heard that. The whole roof would hold paint better if it weren't galvanized... but the purpose of galvanizing was to make the steel last, whether it was painted or not. If the caps were not galvanized, they'd be prone to rust out from water trapped between the caps and sheets, and rust out from behind the paint like a modern day automobile. I wonder if the caps were formed from steel sheet that was galvanized on one side only. Seems like a rather deep draw to be cold formed, though. Wish there was some SRECo. literature that explained the production of their roof system.

Dennis Storzek


Dave Parker
 

Tim et al:

I can't speak to later years, but the 1931 CBC variously refers to these as "transverse caps" and "mullion caps".  Neither term appears in the Dictionary of Terms (nor does "seam caps"), only in the pages describing roof construction (both "all-metal" and "flexible outside").

Although it does not say so explicitly, the wonderful drawings seem to suggest that all exposed metal was galvanized, including the caps.  At least to my eye.

Dave Parker
Riverside, CA