Donut effect - Page 2

Beginner and pro baristas share tips and tricks for making espresso.
User avatar
malachi

#11: Post by malachi »

Are you talking "donut" as in where extraction begins in a donut pattern around the bottom of the basket or a "donut" as in early blonding in a ring pattern around the edge of the basket?

If the former - how far out the basket is the ring? Is it at the edge? Do you also get early blonding?

If the latter - do you tap the side of the portafilter with your tamper during the tamping process ("to knock loose grounds off")?
"Taste is the only morality." -- John Ruskin

ChrisC

#12: Post by ChrisC »

HB wrote:Really? I thought it so laughably ridiculous that I could not bring myself to comment on it. Removing the tamper so fast it creates a vacuum that lifts the puck... Right. :lol:
I've done it, repeatedly. Especially when I was trying out a tamper that had been machined to fit the basket exactly -- unless I pulled it out incredibly slowly, the puck would lift on one side. Think about it, it's just like pulling the plunger back on a needle to draw blood. The air needed to fill the gap between the tamper and the edges of the basket has to come from somewhere -- if you pull fast enough, it needs to be a lot of air fast, and there are all those little holes at the bottom of the basket...

Cerini Coffee & Gifts: official US importer for Olympia Express
Sponsored by Cerini Coffee & Gifts
User avatar
shadowfax

#13: Post by shadowfax »

ChrisC wrote:Think about it, it's just like pulling the plunger back on a needle to draw blood. The air needed to fill the gap between the tamper and the edges of the basket has to come from somewhere -- if you pull fast enough, it needs to be a lot of air fast, and there are all those little holes at the bottom of the basket...

Do you tamp with wet coffee? ground coffee is quite porous, and lever espresso machines draw air through it (packed) every time they are used (unless you draw the piston up prior to locking in the basket). It is, in fact, not like pulling a plunger back on a needle to draw blood: nothing in that equation is porous like coffee. I suspect that that the loss of adhesion you experience drawing the piston up comes from something else in what you're doing.
Nicholas Lundgaard

User avatar
HB
Admin

#14: Post by HB »

I've never owned a tamper that fit the basket so tightly it could be used as a syringe, but if you use a bottomless portafilter, you can hear the air being pulled through the puck during the upstroke on a lever machine. I keep the portafilter just short of snug until the piston approaches the port for filling, then snug it down. Once the puck is saturated, you can see the espresso on the bottom of the basket being sucked back in during the upstroke. A smooth lever action will reduce the impact to the puck's integrity, but the flow for the second pull is always faster because of the fissures caused by the upstroke.
Dan Kehn

ChrisC

#15: Post by ChrisC »

Hmm, good point about coffee being porous -- I just assumed that when it was tightly packed it wasn't quite porous enough... Maybe I was using a finer grind, or tamping harder than you...?

User avatar
shadowfax

#16: Post by shadowfax » replying to ChrisC »

Do you think you could take some pictures of what your broken pucks look like? That might be helpful for us. I have trouble believing that you could be tamping that much harder/grinding finer than anyone else--if it were that significant, you would be choking your machine to death. ;)

My first thought would be that a tight fit makes it hard to pull the piston out properly, and if you're not careful, maybe you tilt it as you pull up? That's just my off-the-wall guess.
Nicholas Lundgaard

ChrisC

#17: Post by ChrisC »

That's the thing, the fit is so tight you can't tilt it at all when the piston is in the basket -- forces you to tamp perfectly flat. I'll see what I can do about pictures, though.

Artisan Plus: complete coffee greens inventory management service
Sponsored by Artisan Plus
User avatar
cafeIKE
Supporter ★

#18: Post by cafeIKE »

erics wrote:Portafilter baskets can, over time, build up scale which is hardly visible with the naked eye BUT the sight was amazing to me when viewed around 20X magnification.
A pf and basket cleaning option


from Importance of regular backflush/cleaning