On October 2, Michael Gross started the string:  Box Car Crack Filler For Grain Transport in which mention was made of tar to fill cracks in cars (coopering of a form).

In addition, some time back my brother Brian found some correspondence about warm freshly milled floor being loaded into cool (from the overnight air) and the moisture of the flour condensing on the roofs of the cars and then dripping down back onto the grain rendering it unfit for human consumption. Those posts are somewhere back in files years past.

I have just uploaded a folder titled Dednox brochure.

Anyway, the product that the brochure touts is called Dednox, and one of the qualities of this tar/cork product which can be sprayed to apply is that it claims to prevent such sweating of car interiors.  

It was found in the Northern Pacific Company files located at the Minnesota Historical Society, St. Paul, MN.

I found it while researching and it was just one of those things that I found interesting and cannot explain why I otherwise would have shot photos of the brochure.  Perhaps I found it postdate when my brother located the above correspondence.

Of the file I found at the MHS and in other NP Mechanical Dept. files found there also; for some time the NP must have really liked this stuff as it was applied to several thousand of the NP’s newly built boxcars as part of the build process.

Other railroads must have liked it also as in the brochure use on 200,000 cars is claimed.  Note that it can be used on open and covered hoppers.

Of special note is photo 4, which shows its use on the exterior end of NRC 18364 and on the roof surfaces of a car build date 3-46. There are NP reefers of around this build date however the obscured end stencil does not readily allow for positive ID.

However, note the granular surface around and on the roof hatch when the photo is enlarged. In the past this group has talked about roof surface textures. This product could be what otherwise looked to be anything from really heavy weathering to blistering paint and spurred those conversations. The photo caption (lower) mentions "natural red slate granules" applied.  

To bring this full circle, the brochure notes an “estimated 50 year life cycle”. Real life was a bit different as the NP and Omaha traded notes that the compound was breaking loose earlier than 50 years and dropping into loads and otherwise contaminating what it was to protect. Causing them to be rejected just as the earlier interior sweating caused. Ending the of use of this product on the NP and perhaps other roads in the mid to late 50s well within this lists time frame.

                                                                                   Jim Dick – Roseville, MN