My 3rd shots are now as good as my 2nd (if I've done all the rest correctly!

Thoughts?
What you say makes sense, EXCEPT that as the group is a conductor, wouldn't the presence of a cold PF help absorb some of the heat of the group? A heatsink, sort of? (Again, I'm clearly no scientist)TUS172 wrote:What I have learned is to use a blind double basket and filled with cold water between shots. Don't lock the portafilter in tight and lift the lever high enough to suck up some of the water. Dry the screen and do the next shot. It is very effective...
Cooling the portafilter is cooling the espresso after it has passed through a hot grouphead and portafilter basket filled with coffee. Cooling the group head with a towel or using the technique I do daily gets the water somewhat cooler before it passes through the puck in the basket which is stainless steel and pretty resistant to thermal transfer from the surrounding portafilter.