Ends up Aircraft Spruce was selling us expired 3M flowable finishing putty. When it gets old the putty get too thick and kicks way too fast, hardener gets way too runny and full cure does not happen and clogs sandpaper.
Date code on this fresh stuff finally sent to us after 3 prior tries is from 2009. Prior stuff was 2007 and "junk".
The way you read date code is ignore the first two letters, the next number is the year and the next 3 numbers after that is the day of year. This is true on both the hardener and putty. Thus the hardener was made in 2009, the 106th day of the year, (click on image to enlarge to read date code on hardener).
Y9-10-09
