Posted by Mike Jackson on March 04, 2004
Okay, this one might bring back vague memories if you ever had drafting in High School or College. I thought of it today when Jay Utzig at Milligan Higgins was trying to explain the old way of rating glue chip glue. X was the mid point on the scale with 315 gram strength and it went both directions from there. 3x, 4x and 5x ratings were remnants of that scale.
Pencil lead is rated similarly, going from 9B to 10H with lots of alphanumeric ratings in between.
B generally stands for Black and H stands for Hard. HB hits somewhere in between and is often called a #2 pencil, with the good qualities of both grades.
9B, 8B, 7B, 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H and 10H
Just like rating glues, there are several other scales for pencil lead. That was the one I had to learn in my drafting classes.
For most, this info falls into the "factoid" category: Basically useless info to most.
For glue chippers, just use the gram strength scale and ask for 164 gram strength when ordering glue.
Mike Jackson
Denver Chapter of the Letterheads