My personal experiences are similar to a lot of us.  For example, my 1-2-3 blocks were about .001 oversize and not all that hard.  From kindness, I made the presumption that the blocks were purposely oversize so that they could be ground to size by the user.  Yeah, right.

I was luckier with my twenty-something-year-old MSC gauge blocks, for accuracy that is, but they also confirmed a long, long suspicion.  The set came with an inspection report including hand-written measurements and the specified tolerances.  I was pleased to see a comfortable margin between the measurements and the tolerances.

One evening, needing to do something with my hands while watching the news, I decided to check my set of "tenths" micrometers and their standards against the gauge blocks.  All went well until I happened to compare my measurements with the gauge block inspection sheets.  I was surprised to see that the first measurement didn't correspond with the recorded entry.  Nor the second ... nor the third .... and so on.

The blocks that I measured were all within specified tolerances but the so-called "inspection sheet" appeared to be an exercise in creative writing.  Maybe someone was assigned to fill in the blanks with arbitrary numbers - as long as the numbers were within the tolerance envelope.

Re-reading Willie's post, I could envision him sorting through the sets, cleaning and lubing the blocks as he went until he assembled a quality set for a bargain price - a very good idea in my opinion !  I wondered about the last time that I'd cleaned my set and to my embarrassment, I couldn't even recall the year.  Guilt motivated me to get the gauge block set out and spend over an hour cleaning them.  I found this:

   

Happily, I didn't find deterioration on the remainder of the set or on my measuring tools except for a small cast-iron angle plate.  The object lesson for me is obvious, of course.

But the incident made me wonder about cleaning and maintenance.  I looked at the online Starrett recommended procedure and it made sense, mostly, although I was surprised to find that gauge blocks should be replaced every year.  Huh ?  Even in a production environment this sounds extreme if their recommended handling and usage procedures are followed.

My WAY overdue maintenance procedure is to wipe the blocks down with one of those soft cloths that come with eyeglasses.  After that, a little swipe of baby oil (on my finger) to prevent "lesions" like the one shown in the above photo, LOL.  The baby oil thing was just because I happened to have some - the reason is long forgotten.  Probably some very light oil, sewing machine oil maybe, would be a better choice.

So now that the subject has come up, I'm curious about how the rest of you maintain your gauge blocks.  Any comments ?