What factors influence grind? Freshness? Variety? Other?

[Mach]

I'm using a Carimali grinder and this week have been pulling great shots of Counter Culture Twin City Express (roasted 1/31) with my ECM Giotto. The grinder is set at 3.4 (generally I grind between 3 and 3.5). On Friday I received a sample of an espresso blend and this morning I figured I'd give it a try so I cleaned the grinder, and poured in some of the new blend. At 3.4 my cup was full in about 4 seconds so I dropped it down to 3.1. Maybe 10 seconds. So, for the first time ever, I dialed down to 2.8 (didn't sound good) and gave it a little extra with the tamper. Close, but still too fast. That shot I tasted, but I didn't like it so I cleaned the grinder, put it back on 3.4 and went back to the Twin City Express. Gorgeous, thick, creamy 25-second shots. So is the other coffee stale? A harder variety? Dehydrated? This may be elementary, but I couldn't find the answer. Thanks for your thoughts.

[cannonfodder]

How long ago was it roasted? It could be stale and running fast, or it could be ultra fresh and needs more degassing time. Stale beans have almost no crema; too fresh and it will be all crema, but will go flat in seconds.

The degree of roast along with the type of beans used will also make a difference, along with humidity. I have a couple of blends that will shift quite a bit on the grind just because of the beans used.

[ordo.dk]

Humidity is also a factor...