lastly, where do u guys learn best practices for espresso for the gaggia classic? noticed that for youtube, different people give different advice, not sure which to trust more.
i used a single boiler before. there are 2 main issues, 1st is to wait before steaming which you already know. i never found this much of a problem unless you entertain guests who want to drink lattes.
the 2nd is temp stability. the temp in the boiler can swing by 30 degrees! so it can either mean overly bitter or overly sour shots. to get things right involve timing when you start to pull your shots in the boiler cycle boiler cycle (aka temperature surfing) the tricky thing is that different revisions of a machine will have different components (usually thermostat and heating elements) and hence different boiler cycles. 110v vs 220v versions will also have different boiler timings!
when you have more experience you can mod your machine with pid kits to control the fluctuation.
https://kabalin.blogspot.com/2014/03/gaggia-classic-controlling-temperature.html
if you are not keen to pid it (i never did with mine), here is one quick and dirty method:
1. make sure your machine is warmed up. (20mins, with portafilter partially locked in).
2. grind, remove portafilter, fill basket, and tamp.
3. before inserting the portafilter, wait until the boiler starts boiling and stops (you are at the peak temp, too hot).
4. flush the grouphead until you don't see flash boiling (no steam and bubbles appearing at the shower screen). stop flushing, (you should be at a temp that is just below boiling).
5. insert portafilter and brew. (don't take too long to carry our steps 3-5 otherwise your portafilter will lose its temperature).
6. wait for espresso to cool a bit. taste it. profit?!
too bitter - water too hot, flush more next time
too sour - water too cold, flush less next time.
i highly recommend to do this practice with highlander beans until you get to be very consistent and familiar. they are the easiest to brew and trust me i have tried from many different roasters. don't change beans when you are at the early learning stage as you'll need to change other parameters and may get confused. go to highlander and drink a few shots so you get a reference how a balanced espresso should taste.
how much to dose? really depends on what baskets you are using. i recommend 15g if you are using the stock 58mm portafilter baskets.
how fine to grind? grind fine enough so that a 15g dose will produce a 30g of espresso within 25-30secs.
how hard to tamp? just tamp until you can't compress the beans further. don't overexert. don't do a fancy feather light tamp. don't nutate. this will get you the most consistency.
there is another technique to get consistent temperature but that involves using a timer to countdown the cooling of the boiler from its peak temperature. you will need to do alot of experimentation. online people are saying to wait for the boiler to cool for 20-30secs after the boiler stops boiling. but this really depends on which version or voltage variant you are using. you can go to home barista or gaggiauser group forums to ask what is the correct cool down time for your version of the classic.
have fun and take your time.
