Finger Swipe Dosing ==> Sub-Par Shot?

Beginner and pro baristas share tips and tricks.
User avatar
another_jim
Team HB

#1: Post by another_jim »

Most people new to espresso, whether at home or in non-Italian bars, are taught to dose the basket by filling it loosely with grinds, then swiping their finger across the top. My guess is that more often than not this leads to sub par shots.

This is not a discussion of how much to dose, but how much head space to leave between the puck and the shower screen. The puck absorbs water and expands during the shot. Experts like Petracco in the Illy book, as well as many people's experience, suggests that the puck should have enough room so it doesn't hit the shower screen. This is particularly apparent on some groups like the Elektra's, but is somewhat true on almost all groups.

In most cases, finger swipe dosing doesn't leave enough head space, and the puck does contact the shower screen. It may be that in some cases finger strike dosing produces optimal shots, but more often, it does not. It is certainly not the way newbies should be taught to dose. Instead, they need to know about the need for some head space.

Despite its fatal flaws, finger strike dosing is both simple and consistent. Is there any proper method of dosing below the top of the basket that is just as simple and consistent?
Jim Schulman

Gus

#2: Post by Gus »

I have recently raised the importance of headspace beyond all other dosing tips and suggestions. While doing my weekly cleaning I noticed that the dispersion block of my machine protruded further into the basket than I was really allowing for. I was trying to pull 17 and 18 gram updosed shots seeking a sweeter result in the cup. What I was getting was a much higher occurrence of early shot channeling and not enough consistency to tell if the results were truly what I was looking for. After looking at the dispersion block compared to my tamper I realized that the base of the tamper was slightly thicker than the dispersion block. I decided that I would downdose until I found something that with a modest tamp would leave the top of the piston just below the rim of the basket. What I have found is that 14 to 14.5 grams is the limit for this with an LM ridgeless double and my machine. I have seen a dramatic increase in shot consistency. I am now working on dialing in the grind at this dose to alter the flow in an effort to chase after a sweeter more balanced result. I don't think I can go much higher than 14.5 without getting a deeper basket.

Darn I posted a reply without fully reading and now I am editing to offer an answer to the final question. I think the only way to dose below the rim of the basket consistently would be to pre weigh the dose, grind and clear the chute completely, and then WDT until you had an even surface, then tamp.

Gus
Gus

Insert catchy phrase of choice here

User avatar
AndyS

#3: Post by AndyS »

another_jim wrote:In most cases, finger swipe dosing doesn't leave enough head space, and the puck does contact the shower screen....Is there any proper method of dosing below the top of the basket that is just as simple and consistent?
Sort of depends on the grinder and the density with which it delivers grinds into the pf, no?

For instance, the Versalab produces particularly fluffy grounds. If one finger swipes those grounds, then tamps, there will be lots of headspace. Similarly if one WDTs and finger swipes.

Rat-tat-tat doser flicking (as the coffee is grinding) also helps with fluffiness, in my experience.

Perhaps the finger swipe is OK if the grinder and/or grinder technique is appropriate?

Also, you don't mention those french-curve tools that swipe below the rim. Have you tried them and not liked them?
-AndyS
VST refractometer/filter basket beta tester, no financial interest in the company

billm3

#4: Post by billm3 »

another_jim wrote:Is there any proper method of dosing below the top of the basket that is just as simple and consistent?
On my QM Alexia, the best most consistent shots are obtained with the finger swipe. I actually slightly concave into the basket with my finger, then tamp. I have never weighed the result, but this gives me a tamp that is slightly below the ridge in the QM double basket. This (for me) gives the optimum head space.

I think that answers your question.

Bill

User avatar
edwa

#5: Post by edwa »

Interesting thoughts, enough to try an experiment with the tools on hand. Thinking I might get enough headspace for the expanding puck I pulled out the triple basket and filled it with 15 grams and used the WDT to distribute it evenly and then tamped. I can see just a little residue of grounds left on the dispersion screen so I should lower the dosage, BUT what was interesting was how fast the shot pulled for the same grind setting that is a tight ristretto in a double basket. Obviously, I'll need to tighten the grind quite a bit but all in all it was not a bad tasting shot for such a fast pull. I've already had my mornings worth of caffeine so I'll probably try some more tomorrow. I've always followed Klatch's recommendation to updose but it does cause the expanding puck to contact the screen quite easily. Once I get the new grind setting dialed in it should interesting to compare the 2 tastes AND if I can discern the difference. :oops:

User avatar
another_jim
Team HB

#6: Post by another_jim »

I was looking for something so simple and so by the numbers that it would please even Schomer.

More generally, go back to 1998 to 2002. People bought their Silvias and Classics, MDFs and Rockys, went to alt.coffee, and got the shot making drill. It was adapted from Schomer, could be communicated in a few paragraphs, and was easily learned.

The only problem is that it was wrong in several details.

Should we come up with a new drill?

Perhaps: weigh your dose (start at around 15 grams, adjust to taste), use a bottomless (learn to pack and level right), cut shots when they go blond (latest when they put a pale spot on the crema), adjust the grinder for the right shot time (so the shot blonds at 25 to 30 seconds) .

Or should we give up on drills?
Jim Schulman

User avatar
edwa

#7: Post by edwa »

How does that French tool work for below the rim? You wouldn't be able to swipe it across like the photos show, do you just insert it and spin?

User avatar
AndyS

#8: Post by AndyS »

edwa wrote:How does that French tool work for below the rim? You wouldn't be able to swipe it across like the photos show
Sure you can, try it with your doser lid.
-AndyS
VST refractometer/filter basket beta tester, no financial interest in the company

User avatar
edwa

#9: Post by edwa » replying to AndyS »

Okay, but as I suspected, it carves out more in the middle than at the entry and exit. Am I missing something?

EricL

#10: Post by EricL »

You could taking a piece of dense cardboard, like back of a writing tablet, cutting out a piece around 70 mm across, and then cutting the sides so there is a 58 mm section that extends down a couple mm or so.
try spinning this in the basket. Haven't tried it, just had a thought.

|||||||||||||||||||||||||||||||||||||
------|||||||||||||||||||-----------