I used Weather-It to slightly darken an individual board lumber load for a flatcar around 1985. The darkening effect has never stopped. The load is still getting darker. I would not use it or any similiar formulation again. An alcohol based dye may give better results.
Also Micro Mart has a similar product to the orginal:
https://www.micromark.com/Age-It-Easy-Gray
Also, they have some other shades.
Rick Jesionowski
Rule 1: This is my railroad.
Rule 2: I make the rules.
Rule 3: Illuminating discussion of prototype history, equipment and operating practices is always welcome, but in the event of visitor-perceived anacronisms, detail descrepancies or operating errors, consult RULE 1!
I remember that product. Haven't seen it in a while.
Aim Products has a similar line (scroll down)
http://monroemodels.us/aim.weathering.htm
and Vallejo has similar products:
https://acrylicosvallejo.com/en/categoria/hobby/weathering-effects-en/
Don't forget "Rustall"
http://www.rustall.com/
Hope that helps, Ed
I did a search for "weather-it", a preparation that was first available I think in the late seventies; no results. Anyone know if this is still being made?