I have a gondola that is being relettered as a purchased used car with a quick block out job on the old lettering. There are a few issues that I have with the car, which is an Athearn BB gondola. The lettering is bad on it and I am planning to replace it. I have recreated most of the lettering. However there is one piece of lettering that I can’t recreate leading to part 1 of my question: Does anyone know of any HO decal sets where I might find a “Built by Thrall” decal in white? (Reference the mentioned Athearn 50’ BB Gondola, which is GN blue.) Part of the new lettering for the car leads to question 1a: If a car is reshopped for a new owner, the date on the dimensional data would say New and the reshopped date e.g. New 10-72. The BLT date would be 3-66, correct? (Unfortunately that’s one detail I can never remember. You would think I would remember that as much equipment as I paint and decal. 
) As this car is to be a second hand car, I would need to do a little bit of weathering on the car as the car is still fairly new which leads to part 2 of the question: Has anyone ever tried to brush paint with Floquil’s instant weathering spray? I’d image that it could be sprayed into a separate container and done that way but I am not sure if that will work. (And of course I would need a little bit of practice to get the weathering right.) Thank you for any assistance you can provide.
Microscale decal set 87-1, Freight car data / Railroad Roman has 2 Built by Thrall decals in white.
Sorry I do not have the knowledge to answer questions 1A & 2.
Hope this Helps
No.
“NEW” only appears next to the weigh date when it is initially weighed by the manufacturer. If the car is reweighed then the “NEW” is replaced with a code representing the railroad or shop that did the reweighing.
If the example car was built in March 1966, when built the date next to the weight data (which indicates when the car was weighed) will read “NEW 3-66” and there might be a smaller “BLT 3-66” at the other end of the car with the rest of the dimensional information.
If the car is re-weighed and the LT WT (light weight) of the car has changed (through natural wear, or repairs/changes to the car) the “NEW 3-66” weigh date will be painted over and replaced with something like “SC 10-72” where “SC” is the code representing the shop that did the weighing. (I’m not familiar with GN’s shop locations and codes, so “SC” is a made-up example.)
Note also that this date only needs to change if there is actually a change in the car’s weight when it is shopped & re-weighed.
When the car changes ownership, it might not receive any shopping other than the new paint over the reporting marks. So the re-weigh date may not match the change in reporting marks.
Conversely, a car could actually receive a full repaint, but if there’s no change in weight when it is shopped, the “new” date could actually be painted back on. I’ve even seen freshly repainted cars (usually tank cars) with dates almost 10 years previous.
As to using Floquil “Instant Weathering” with a brush - yes it is possible. One sprays the paint into a small cup or jar. Remember that the pressure flow will cause the paint to possibly splatter out of the cup, so don’t do it near you project(s). Floquil spray is a laquer so it’s best sprayed outside anyway.
Personally I shay away from the “instant” weathering items. Weathering is individual to most cars, depending on age, location and service, etc, etc. I do most of my weathering with a brush using a variation on the “dry brush” technnique. This is where you getr some paint on the brush and then wipe most of it off and use light strokes on the model to let the paint build up. Start lightly, then you can always add more dirt/weathered colors. It’s harder to remove excess than add slowly. For certain effects I use “stippling” which is to use a very little paint on the end of the bristles and gently tap the brush onto the surface. Again work lightly and add more as you desire. If you can practice on some extra plastic, a “junker” car or some cardboard until you get the feel of it. I use several shades of earth tones, military browns, light grays and such. Look at how cars like yours weather and try to catch those effects.
Good luck.
Part of why I want to use the instant weathering is that I have no idea of what precise colors I would need to use. And everything that I have read, that paint can be used when one isn’t sure how to weather cars, which I am not. I was planning to use the “dry brush” with the instant weathering paint anyway.
The rules on re-weighing did change over the years, but the re-weighing was mandated by either the AAR or the ICC, and had to take place within specified timeframes depending on the era and the particular car types. Tank cars and live poultry cars were exempt, but all others required re-weighing. Whether or not the weights changed, the car was required to be stencilled with the scale symbol and date of the re-weighing. (I’m guessing that Chris intended the “e” on the word “date” to be an “a”).
Strictly speaking “NEW” could appear only within a specified time immediately after the car was built or for a similar period if the car was re-built. Cars were considered to be re-built only if the frame had been structurally modified, so even a car with new sides, ends and roof, riding on new trucks, was not considered re-built as far as the re-weigh regulations were concerned.
As for weathering, an alternative would be artists’ pastels. You only need a few basic earth tones and perhaps a black and a grey, and the cheaper ones work just fine. I rub them on coarse sandpaper, then dump the resulting powder into any suitable container. Use a suitable cheap brush to apply the powder, much as you would paint, then dust if off as necessary using a wide brush. If you don’t handle the car too much, you don’t even need to overspray it with a clear finish.
This gondola, four bucks “used” at my LHS, had poorly-applied D&H decals over its original Pere Marquette lettering. I stripped off both, then re-painted it, using Champ decals to make it a Lehigh Valley car. After some initial airbrush-applied weathering, I bulged the sides using a 200 watt soldering iron, t