Topics

Wood sheathing differential weathering reasons


Andy Carlson
 

My interest in lumber has led me to examine photos of single sheathed freight cars in a critical way. Unlike double sheathed cars, single sheathed cars usually did not have tongue & Groove edges while double sheathed not only had the T&G edges, they were commonly milled with a 'V' along the board's edge giving the characteristic finished look so attractive on both freight cars and passenger cars.

Logs milled into lumber start out as cylindrical and are sawn into flat panels where individual boards are sliced from. Depending on the location of this sawing relative to the circular ring pattern of the log, it will create different styles of finished lumber. Where the rings, as viewed from the board's edge, stand vertical that is called 'vertical grain' or quarter sawn. Boards with the ring grains running horizontally from side to side is called 'flat sawn'.

Understanding the reasons for the existence of tree rings in lumber is helpful in seeing the weathering differences found in ageing milled lumber. Each ring zone in a tree is from a single season of growth, particularly in temperate forests. The broader area is from spring growth and is the most rapid growth the trees will have in a season. This portion of wood growth is called "spring wood'. After this fast growth, the the slower growth of summer is much denser but also much slower in growth producing the dark ring which is called 'summer growth'. Summer growth is both denser and narrower and the denseness makes it the strongest portion of a log. The much faster growth of the spring wood is less dense and is therefore of less strength. The favorite lumber to mill into T&G was from old growth trees, where the darker forest from all of the neighboring trees blocking much of the light made for a lot of the year's tree growth to be somewhat minimal. This slower growth made for a much higher percentage of summer wood and any old carpenter will tell you that kind of lumber is the best, especially when quarter sawn into vertical grain wood.

Returning to the differences of flat and vertical grain sawed lumber; if the boards are cut from the flat grain area of a slab at the mill the face of the boards will have the characteristic look of ovals and wavy lines, which is what is seen of the rings as they are exposed to the cut lumber. Remember that the spring wood is less strong and that the face of the flat grain on a board will have that board exposed to the weather with the higher % of weaker wood. I like to call attention to wood fence posts. Commonly beveled at the top to reduce the pooling of standing water, accelerating rot, the tops of these boards clearly show the ring structure in the horizontal and circular view. After a few years, you will see that the areas within the rings will retreat downwards due to the softer spring wood's less resistance to rot. This same principle is at work on milled freight car siding. Since the commonly milling methods produce a mix of flat grain and vertical grain boards it was not uncommon for sheathing boards to also be a mix of mill cuts. Nowadays, many of the more premium boards are pulled out of the green chain to be sold at a premium due to their recognized better quality.

So a freshly sheathed SS car will usually have a mix of these boards and after a few years, the boards with faces of predominantly flat grain (spring wood) will decay noticeably faster. I have a sample photo of an older single sheathed car, a WP 40' box car in the 15001-16000 series.
Inline image

The difference between the boards with the paint intact vs. the boards with silvering weathering where the paint has flaked off is striking. The boards which are in between flat grain and vertical grain have ring patterns varying from within the two extremes and will have a variable amount of face spring wood and will show slower rotting of the flat grain wood but faster rot than the vertical grain boards.

Notice that these boards are truly aging, but the tightness of the boards to each other remains pretty good. No leaks from sand or wheat which will pour out.

In the history in this hobby of recreating freight cars in the form of models has shown the steady reduction of the very deep and wide grooves manufacturers used to delineate the individual boards. Some experiments have making the boards of different thicknesses, such as Tichy cars with boards that stand both outwards and inwards relative to each other. As shown in this closeup picture these boards do not show this kind of board differential at all.

As for how do we emulate the style visible in the photo for our miniatures? I am being more convinced that subtle groove lines coupled with differential painting is the way to more closely achieve this look. If I weren't so slow (lazy) I would be doing some painting experiments.

You all please stay safe and do well,
-Andy Carlson
Ojai CA


Brian Stokes
 

Andy, 

Fascinating synopsis, thank you for sharing. I wonder if some kind of decal would work in helping recreate this. 

--
Brian Stokes
North Point Street in Proto:48


Matt Goodman
 

Thanks for this, Andy. In the past couple of weeks, I’ve attempted to replicate this “dark board” effect using a micro brush and dark or extra dark versions of Pan Pastel's Umber, Burnt Sienna or Iron Oxide. Each has it’s own effect.

In any case, I’ve been curious or confused as to why some boards had short sections of dark coloring, while others were longer. This explanation, well, explains that. And knowing the “why” helps me better replicate it.

Matt Goodman
Columbus, Ohio, US 

On Dec 1, 2020, at 2:36 PM, Andy Carlson <midcentury@...> wrote:

My interest in lumber has led me to examine photos of single sheathed freight cars in a critical way. Unlike double sheathed cars, single sheathed cars usually did not have tongue & Groove edges while double sheathed not only had the T&G edges, they were commonly milled with a 'V' along the board's edge giving the characteristic finished look so attractive on both freight cars and passenger cars.

Logs milled into lumber start out as cylindrical and are sawn into flat panels where individual boards are sliced from. Depending on the location of this sawing relative to the circular ring pattern of the log, it will create different styles of finished lumber. Where the rings, as viewed from the board's edge, stand vertical that is called 'vertical grain' or quarter sawn. Boards with the ring grains running horizontally from side to side is called 'flat sawn'.

Understanding the reasons for the existence of tree rings in lumber is helpful in seeing the weathering differences found in ageing milled lumber. Each ring zone in a tree is from a single season of growth, particularly in temperate forests. The broader area is from spring growth and is the most rapid growth the trees will have in a season. This portion of wood growth is called "spring wood'. After this fast growth, the the slower growth of summer is much denser but also much slower in growth producing the dark ring which is called 'summer growth'. Summer growth is both denser and narrower and the denseness makes it the strongest portion of a log. The much faster growth of the spring wood is less dense and is therefore of less strength. The favorite lumber to mill into T&G was from old growth trees, where the darker forest from all of the neighboring trees blocking much of the light made for a lot of the year's tree growth to be somewhat minimal. This slower growth made for a much higher percentage of summer wood and any old carpenter will tell you that kind of lumber is the best, especially when quarter sawn into vertical grain wood.

Returning to the differences of flat and vertical grain sawed lumber; if the boards are cut from the flat grain area of a slab at the mill the face of the boards will have the characteristic look of ovals and wavy lines, which is what is seen of the rings as they are exposed to the cut lumber. Remember that the spring wood is less strong and that the face of the flat grain on a board will have that board exposed to the weather with the higher % of weaker wood. I like to call attention to wood fence posts. Commonly beveled at the top to reduce the pooling of standing water, accelerating rot, the tops of these boards clearly show the ring structure in the horizontal and circular view. After a few years, you will see that the areas within the rings will retreat downwards due to the softer spring wood's less resistance to rot. This same principle is at work on milled freight car siding. Since the commonly milling methods produce a mix of flat grain and vertical grain boards it was not uncommon for sheathing boards to also be a mix of mill cuts. Nowadays, many of the more premium boards are pulled out of the green chain to be sold at a premium due to their recognized better quality.

So a freshly sheathed SS car will usually have a mix of these boards and after a few years, the boards with faces of predominantly flat grain (spring wood) will decay noticeably faster. I have a sample photo of an older single sheathed car, a WP 40' box car in the 15001-16000 series.
<Screen Shot 2020-12-01 at 10.36.16 AM.png>

The difference between the boards with the paint intact vs. the boards with silvering weathering where the paint has flaked off is striking. The boards which are in between flat grain and vertical grain have ring patterns varying from within the two extremes and will have a variable amount of face spring wood and will show slower rotting of the flat grain wood but faster rot than the vertical grain boards.

Notice that these boards are truly aging, but the tightness of the boards to each other remains pretty good. No leaks from sand or wheat which will pour out.

In the history in this hobby of recreating freight cars in the form of models has shown the steady reduction of the very deep and wide grooves manufacturers used to delineate the individual boards. Some experiments have making the boards of different thicknesses, such as Tichy cars with boards that stand both outwards and inwards relative to each other. As shown in this closeup picture these boards do not show this kind of board differential at all.

As for how do we emulate the style visible in the photo for our miniatures? I am being more convinced that subtle groove lines coupled with differential painting is the way to more closely achieve this look. If I weren't so slow (lazy) I would be doing some painting experiments.

You all please stay safe and do well,
-Andy Carlson
Ojai CA

<Screen Shot 2020-12-01 at 10.36.16 AM.png>


np328
 

   If I might add to your well written post above, I cannot help but wonder if the older builders knew more than we give them credit for.  
While helping a relative put down patio decking decades ago, my brother and I were given some lessons by this relative that seemed obsessive to us then however like many things in life, the bulb went off in the brain years later when I recalled - So that is what he was talking about.... And to expand, this was well prior to composite or engineered wood.  The relative would upbraid my brother or I when we would set a board so that cupping would take place rather than crowning. 

      This link below explains it better than I can, however before you go there, also read in the article about how moisture affects the boards. A double sheathed car may protect the lading more, however once the sun hits the outside sheathing, inside the double sheath is a dead air space. The water may have well drained if it got past the outer sheath however the wood on the inside will be more moist than the outside. With shingle sheathed cars I would imagine there is some moisture movement also and affected in temperature changes inside vs outer. 

   Our railroad cars are different in that the siding is on a vertical rather than horizontal plane.  Here is the link :https://www.thespruce.com/deck-board-installation-1825145    

There is much more data out there on the matter and more learned folks on this list that I would hope chime in. 
                                                                                                                                                        Again Andy, thanks for writing the post     Jim Dick - Roseville, MN


Charlie Duckworth
 

Andy
Thanks for the image and overview.  I went to the work bench and did a ‘beta’ test on a Proto 2000 hopper.  Using a needle in a pin vice I added some grain in a couple places and the used Vallejo black gray and black to replicate the weathered wood as in your photo of the WP car.   After the paint was dry I used the pin vice again to replicate more grain.

This is only a test to see how the weathering of wood can be pulled off - am looking for other thoughts and I’ll try more on this car and post the results. 
--
Charlie Duckworth 
Omaha, Ne.


O Fenton Wells
 

Interesting concept Charlie nice results, like the wire grabs
Fenton 


On Dec 6, 2020, at 8:05 AM, Charlie Duckworth <omahaduck@...> wrote:


<4B36A0FA-325F-4B1A-A75A-D3A8CA3C6CFF.jpeg>
<E71A084D-17AF-4C56-842C-01592CC8599B.jpeg>
Andy
Thanks for the image and overview.  I went to the work bench and did a ‘beta’ test on a Proto 2000 hopper.  Using a needle in a pin vice I added some grain in a couple places and the used Vallejo black gray and black to replicate the weathered wood as in your photo of the WP car.   After the paint was dry I used the pin vice again to replicate more grain.

This is only a test to see how the weathering of wood can be pulled off - am looking for other thoughts and I’ll try more on this car and post the results. 
--
Charlie Duckworth 
Omaha, Ne.


Douglas Harding
 

Looking very realistic. Nice job.

 

Doug Harding

www.iowacentralrr.org

 

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Charlie Duckworth
Sent: Sunday, December 6, 2020 7:06 AM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Wood sheathing differential weathering reasons

 

Andy
Thanks for the image and overview.  I went to the work bench and did a ‘beta’ test on a Proto 2000 hopper.  Using a needle in a pin vice I added some grain in a couple places and the used Vallejo black gray and black to replicate the weathered wood as in your photo of the WP car.   After the paint was dry I used the pin vice again to replicate more grain.

This is only a test to see how the weathering of wood can be pulled off - am looking for other thoughts and I’ll try more on this car and post the results. 
--
Charlie Duckworth 
Omaha, Ne.


Tim O'Connor
 


I wonder if a pencil-style coarse sanding stick would be easier if you needed to do the whole side like this car.
Your technique works on USRA and WE gondolas too!


On 12/6/2020 8:05 AM, Charlie Duckworth wrote:
Andy
Thanks for the image and overview.  I went to the work bench and did a ‘beta’ test on a Proto 2000 hopper.  Using a needle in a pin vice I added some grain in a couple places and the used Vallejo black gray and black to replicate the weathered wood as in your photo of the WP car.   After the paint was dry I used the pin vice again to replicate more grain.

This is only a test to see how the weathering of wood can be pulled off - am looking for other thoughts and I’ll try more on this car and post the results. 
--
Charlie Duckworth 
Omaha, Ne.

Attachments:



--
Tim O'Connor
Sterling, Massachusetts


Charlie Duckworth
 

Interesting weathering on the various board colors. I was trying to replicate the image Andy posted with just the grain showing through in a few spots.  As to your more weathered car the WWI aircraft modelers have decals available to replicate the wood paneling used on German airplanes.  It’s quite convincingly. 

On Dec 6, 2020, at 8:01 AM, Tim O'Connor <timboconnor@...> wrote:



I wonder if a pencil-style coarse sanding stick would be easier if you needed to do the whole side like this car.
Your technique works on USRA and WE gondolas too!


On 12/6/2020 8:05 AM, Charlie Duckworth wrote:
Andy
Thanks for the image and overview.  I went to the work bench and did a ‘beta’ test on a Proto 2000 hopper.  Using a needle in a pin vice I added some grain in a couple places and the used Vallejo black gray and black to replicate the weathered wood as in your photo of the WP car.   After the paint was dry I used the pin vice again to replicate more grain.

This is only a test to see how the weathering of wood can be pulled off - am looking for other thoughts and I’ll try more on this car and post the results. 
--
Charlie Duckworth 
Omaha, Ne.

Attachments:



--
Tim O'Connor
Sterling, Massachusetts
<cnw_X203181 2bay hopper WE mofw exCB&Q_ National Type-B trucks ChicagoIL 10-1979.jpg>

--
Charlie Duckworth 
Omaha, Ne.


Bruce Smith
 

Charlie,

That's a very nice effect! If the car was undec, I would probably work in reverse, painting the raw wood colors, then chipping fluid, followed by the top coat, but on a decorated car, your approach is very convincing. 

As with all weathering, layers make a huge difference and I cannot wait to see additional weathering.

I'm definitely going to use these colors, and probably add some lighter grey and brown as well.

Regards,
Bruce Smith
Auburn, AL


From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> on behalf of Charlie Duckworth <omahaduck@...>
Sent: Sunday, December 6, 2020 7:05 AM
To: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io>
Subject: Re: [RealSTMFC] Wood sheathing differential weathering reasons
 
Andy
Thanks for the image and overview.  I went to the work bench and did a ‘beta’ test on a Proto 2000 hopper.  Using a needle in a pin vice I added some grain in a couple places and the used Vallejo black gray and black to replicate the weathered wood as in your photo of the WP car.   After the paint was dry I used the pin vice again to replicate more grain.

This is only a test to see how the weathering of wood can be pulled off - am looking for other thoughts and I’ll try more on this car and post the results. 
--
Charlie Duckworth 
Omaha, Ne.


Charlie Duckworth
 
Edited

Fenton
The metal grab irons are included in the P2K parts.  While a little oversized I’m ok on how they look. Not sure why I passed up on buying one of these models when they were first released but they look nice and it’s a very quick build. Only criticism is the interior where the boards are is completely smooth.  
--
Charlie Duckworth 
Omaha, Ne.


mopacfirst
 

And based on my memories, you couldn't work with a better car than a C&S composite hopper if you wanted weathered wood.  Other than those narrow gauge Rio Grande boxcars, of course.

Ron Merrick


Brian Stokes
 

Tim, 

That photo of the hopper in MOW service really shows the effects of the plain-sawn boards well. 

I found Andy's post fascinating and very educational. One thing I still don't understand though is how the board weathers in this way when it is painted. How does the paint weather from the softer rings faster - as can be seen clearly in that MOW photo where there is no paint at all on the soft ring sections vs. the harder part of the ring. 



--
Brian Stokes
North Point Street in Proto:48


Charlie Duckworth
 

I added a little gray to the sides just to see if it helped to break the boards.  The pin vice is shown that I used to scrape off the paint  as well as a tooth pick I used to remove paint off the lettering.  One piece of advice is the acrylic paint needs to be more of a wash.  If it’s applied too thick the head of the pin just removes almost all of it vs allowing the paint to be scratched.  



--
Charlie Duckworth 
Omaha, Ne.


Kenneth Montero
 

Charlie,
 
Regarding the car's interior, Rail Scale Models makes a laser-cut interior wood lining for the Proto 2000 War Emergency Hopper - part no. A205.  Bill Hanley told me about this item.
 
 
Ken Montero

On 12/06/2020 10:49 AM Charlie Duckworth <omahaduck@...> wrote:
 
 

[Edited Message Follows]

Fenton
The metal grab irons are included in the P2K parts.  While a little oversized I’m ok on how they look. Not sure why I passed up on buying one of these models when they were first released but they look nice and it’s a very quick build. Only criticism is the interior where the boards are is completely smooth.  
--
Charlie Duckworth 
Omaha, Ne.


Jim Betz
 

Brian,
  When wood gets wet we say "it raises the grain".  Perhaps the softer
parts absorb more water and raise more - providing a surface that is
easier for dirt to collect and paint to wear?  You can actually feel the
roughness more where the grain is raised.

  Personally, I prefer using "paint methods" for grain than any kind of
physical tool such as scratching the surface or sanding.  Painted
simulation of grain produces, to me, a more effective grain ... because
it is subtler.  The trick is to build it up slowly and paying attention to
the direction and length of the "lines" produced by the brush.  YMMV.
                                                                                       - Jim
                                                                                   - Jim 


Tony Thompson
 

Brian Stokes wrote:

I found Andy's post fascinating and very educational. One thing I still don't understand though is how the board weathers in this way when it is painted. How does the paint weather from the softer rings faster - as can be seen clearly in that MOW photo where there is no paint at all on the soft ring sections vs. the harder part of the ring. 

       Some moisture will penetrate through paint, but more importantly no paint layer is ever without pinholes. The wood under that coat of paint is certainly being affected by moisture, just much less than if it was unpainted. As they say in the coatings business, a coating only delays "the evil day" of failure.

Tony Thompson




Steve SANDIFER
 

Proto and Rail-scale-models missed the slope sheets. They were also wood down to the frame. See photo p. 242 Santa Fe Open Top Cars.

 

 

J. Stephen Sandifer

 

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Kenneth Montero
Sent: Sunday, December 6, 2020 12:13 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Wood sheathing differential weathering reasons

 

Charlie,

 

Regarding the car's interior, Rail Scale Models makes a laser-cut interior wood lining for the Proto 2000 War Emergency Hopper - part no. A205.  Bill Hanley told me about this item.

 

 

Ken Montero

On 12/06/2020 10:49 AM Charlie Duckworth <omahaduck@...> wrote:

 

 

[Edited Message Follows]

Fenton
The metal grab irons are included in the P2K parts.  While a little oversized I’m ok on how they look. Not sure why I passed up on buying one of these models when they were first released but they look nice and it’s a very quick build. Only criticism is the interior where the boards are is completely smooth.  
--
Charlie Duckworth 
Omaha, Ne.


Charlie Duckworth
 

Thanks!

On Dec 6, 2020, at 12:13 PM, Kenneth Montero <va661midlo@...> wrote:


Charlie,
 
Regarding the car's interior, Rail Scale Models makes a laser-cut interior wood lining for the Proto 2000 War Emergency Hopper - part no. A205.  Bill Hanley told me about this item.
 
 
Ken Montero
On 12/06/2020 10:49 AM Charlie Duckworth <omahaduck@...> wrote:
 
 

[Edited Message Follows]

Fenton
The metal grab irons are included in the P2K parts.  While a little oversized I’m ok on how they look. Not sure why I passed up on buying one of these models when they were first released but they look nice and it’s a very quick build. Only criticism is the interior where the boards are is completely smooth.  
--
Charlie Duckworth 
Omaha, Ne.

--
Charlie Duckworth 
Omaha, Ne.


Charlie Duckworth
 

Anyway you could post an image?

On Dec 6, 2020, at 1:46 PM, Steve SANDIFER <steve.sandifer@...> wrote:



Proto and Rail-scale-models missed the slope sheets. They were also wood down to the frame. See photo p. 242 Santa Fe Open Top Cars.

 

 

J. Stephen Sandifer

 

From: main@RealSTMFC.groups.io <main@RealSTMFC.groups.io> On Behalf Of Kenneth Montero
Sent: Sunday, December 6, 2020 12:13 PM
To: main@RealSTMFC.groups.io
Subject: Re: [RealSTMFC] Wood sheathing differential weathering reasons

 

Charlie,

 

Regarding the car's interior, Rail Scale Models makes a laser-cut interior wood lining for the Proto 2000 War Emergency Hopper - part no. A205.  Bill Hanley told me about this item.

 

 

Ken Montero

On 12/06/2020 10:49 AM Charlie Duckworth <omahaduck@...> wrote:

 

 

[Edited Message Follows]

Fenton
The metal grab irons are included in the P2K parts.  While a little oversized I’m ok on how they look. Not sure why I passed up on buying one of these models when they were first released but they look nice and it’s a very quick build. Only criticism is the interior where the boards are is completely smooth.  
--
Charlie Duckworth 
Omaha, Ne.


--
Charlie Duckworth 
Omaha, Ne.