A blast from the past! BN 450018 is a Pullman Standard PS-2 covered, modeled excellently by Tangent Scale Models. The prototype is a 4000 cu ft capacity 3-bay hopper. Back when it was first produced in the early 60's it was a rather large car. It measured nearly 50 feet on the exterior, which was pretty standard for its time. However, these poor cars would be absolutely dwarfed now. Most modern 3-bay hoppers are over 60' in length and are closer to 5000 cu ft in capacity. Even the old and ubiquitous 4650 is much larger than the PS-2 4000.
Surprisingly some of these cars survived into the early 2000's. Tangent Scale Models has a prototype picture of BN 450018 that was taken in 2004 (I based my weathering off of this picture).
BN 450018 was an ex-CB&Q car that was repainted in 1990 into BN's updated scheme. The paint and lettering remained all through the merger and on into the new millenium. After the picture was taken in 2004 it is a mystery as to what happened to 450018. At this point it has most likely been scrapped.
I weathered the car by first Dullcoting, then mixing up some acrylics to a light yellowish-green and covering the car in multiple layers of it. I cleaned off all the lettering, then did a few light filters of raw umber oils. The roof was done with mostly acrylics. I used colors ranging from raw umber, burnt umber, gray, and black to portray the loss of paint on the roof per the prototype. The bays and ends of the car received similar treatment, though not as opaque. The streaks were done with raw sienna oils, with burnt umber for the darker rust. Powders were used to portray grime that had collected on the sill and feathered out. I skipped the Hazmat placards and light graffiti from the prototype picture, as this would be running on a friend's layout that pre-dates those additions.