The addition of the manometer to my ViaVenezia, along with watching a couple vids of Neapolitan baristas utilizing spring lever machines, has resulted in modifications to technique. Previously I was using my flow control to pre-infuse a bit, and then running the shot for 23-28 seconds depending on the coffee.

Now it goes like this:

1. Pre-infusion. Quickly but slowly (yeah, but it makes sense when you do it lol) go from zero flow to full flow and then back down. Can't start at full flow because it makes a mess of the puck, but a moment of full flow does saturate the puck.
2. With pressure around three bar, wait for first drops to emerge.
3. Shut flow lever down to zero flow/pressure, wait five to eight seconds. This completes pre-infusion.
4. Go to full flow (around nine bar) for eight to ten seconds.
5. Gradually back off flow.
6. The moment any blonding begins, stop the shot.

Whether the final step occurs after fifteen seconds or thirty five seconds is irrelevant. I just have to pay attention, and stop the shot at that moment. I'm getting consistently good results with this process.

Curious to know if you involve a shot ratio at all or only go by blonding?

I've not been worrying about ratio. I don't own a scale for espresso... the amount output into the cup comes out roughly the same each time for a given bean. The HairBender, for example, gives me slightly more in the cup before blonding than does the Mott Espresso dark roast. So I'm clearly obtaining a ratio that could be measured. I just don't have it measured.

I used my bottomless portafilter this morning for the first time since installing the pressure gauge and moving to this adjusted workflow. It was very smooth, no hint of channeling. And I got to stop the water-input part of preinfusion sooner. Think I'll use the bottomless for the next many shots, to see just how low I can go with that.

It is cool to hear that technique works for you so well and you use it everyday. I closely watch the stream to see color differences but don't have an eye to exclusively stop a shot based on it. I recently quit using my thermometer for steaming and it has been going quite well with just touch, sight and sound now that I've had a lot of time behind the steamer. I'd like to try the blonding technique to stop a shot too to have another technique under my belt.

I posted this in 'machines' but it really belongs here. Will copy it over, and then delete from that subforum.

Another vid showing the process. Mott espresso dark blend. Longer than usual so I could video it, and not perfect though it tasted good. One cat saying hello throughput the vid.

0:05: start pre-infusion. Start low, ramp up to about 7 bar, drop back down. Note the PID temperature drop even though no liquid is emerging, so we know water is flowing into the puck.
0:23: pre-infusion with little to no pressure for blooming.
0:31: ramp up pressure. Gauge maxed at 11.5 bar, in accordance with brew head 2 bar pressure drop.
1:06: though I've been backing off the flow control already, you can begin to hear the pump dropping off.
1:15: note the temperature, which started at 195, never dropped below 189. Meanwhile the pressure gauge reads 3 bar... and the dimmer lever is dropping on its own at this point! Almost like an actual spring lever.
1:20: the lever has dropped more, and the manometer reads 1 bar. Time to end the shot.
1:29: only the very first few 'blond' drops have come into the cup. So even though the shot took 75 seconds total, there's no bitterness. It's pretty sweet.

Though on examining the following, pre-infusion begins at 0:34 and the shot concludes at 1:50.... so 75 seconds total is not unexpected when emulating a lever shot??