by HB on Sun Mar 27, 2011 10:42 pm
I would not worry about gauge precision; if it reads 9.0 bar and it's really 9.8 bar, so what? Treat the current reading as 'x' and decrease it by 2.0 bar. If the taste profile goes flat and crema production plummets, back up 1.0. If it's still fussy and the taste profile has a sharp edge, try reducing the pressure further. Repeat as necessary.
Dan Kehn