WDT for single baskets and low headspace machines

[Fullsack]

In John's seminal WDT "how to" article, he recommends, "leveling to the top of the filter basket for the greatest consistency in dosing." I know this works great for most espresso machines pulling a double shot, but what about doing a single shot or using a low headspace machine?

My Elektra Semiautomatica is a low headspace machine. If I dose and level to the top of the filter basket, the puck expands into the dispersion screen and throws off the shot. This has also been a problem for me with an E61 group and a single basket.

My question had been, if you can't dose to the top of the basket and level with a straight edge, how do you get an even distribution in the basket? Here is what has been working for me:

In a double filter basket that has been removed from the portafilter, I dose 13.5 grams, keeping the coffee to the outside edges of the basket rather than having the bulk of the coffee in the middle. I continually turn the basket while the dosing is taking place, starting from the outside edges and working inward.

Because the 13.5 grams only fills 2/3 of the double basket, I am able to do the WDT stirring without the yogurt cup. I tilt the basket at an angle and stir back and forth, (I get poorer results with a circular pattern), with a sewing needle, (I keep it stored in a shot glass with some thread in it for easy handling), going from the high side to the low side. I rotate the basket 1/3 of the way around in my hand and repeat the process, rotate 1/3 again and repeat once more. If I encounter large clumps in the basket, I break them up first by stabbing them with the point of the needle and then commence the modified WDT.

To level, I tilt the basket with the higher level of coffee on the high side and do a small circular stirring pattern with the needle towards the lower level end of the basket. The needle is barely below the surface of the coffee during this part of the process. The coffee levels fairly quickly, but will still have a rough surface. Tamp hard and pull the shot, (an easy tamp won't work nearly as well).

Using this variation of WDT and a bottomless portafilter, I'm seeing an even beading during a ristretto pull, no signs of channeling, no splattering and enjoying the best shots I've ever pulled.


http://www.home-barista.com/weiss...ion-technique.html

[RapidCoffee]

In John's seminal WDT "how to" article, he recommends "leveling to the top of the filter basket for the greatest consistency in dosing." I know this works great for most espresso machines pulling a double shot, but what about doing a single shot or using a low head space machine?

Hi Doug. Your suggestion for downdosing is an excellent one. I use it myself on a regular basis, especially during my recent TGP stint.

If I think I've overdosed the basket after a "standard" WDT stir, I'll pop out the funnel, stir again to fluff up the grounds, and relevel to the top of the basket prior to tamping. You can often reduce the dose by a couple of grams this way. For more serious downdosing, I dose by weight rather than volume, declump with a WDT stir, remove the funnel, restir to level the grinds as best I can (trickier when the grinds are below the basket rim), and tamp.

When I revisit the WDT article (now well over a year since its publication on H-B), there are always a few improvements that come to mind. This is definitely one of them. Thanks!

[Fullsack]

When I revisit the WDT article (now well over a year since its publication on H-B), there are always a few improvements that come to mind. This is definitely one of them. Thanks!

Thanks John. I'm pleased, I had something to add to your fine work.

The low headspace/single basket variation may benefit from some refinement before becoming part of your update. I'm not sure that the WDT to leveling sequence can't be improved upon. Maybe WDT, some leveling and WDT again would provide better results.

Another thing that may improve results, with further experimentation, is the length of WDT time and the speed with which it is done. I'm convinced that less is more, when it comes to keeping the fluff of the coffee intact, in the filter basket.

[Fullsack]

The low headspace/single basket variation may benefit from some refinement before becoming part of your update. I'm not sure that the WDT to leveling sequence can't be improved upon. Maybe WDT, some leveling and WDT again would provide better results

Nope, the sequence holds. I played around with it a lot and couldn't find a way to improve it.

[mrgnomer]

With regards to a single I find the dose can be tricky. Too much and you can't lock in or the extraction is compromised, too little and it's hard to get a seal around the edges.

The WDT fluffs up the grind for me to avoid overdosing and evens out dose for a more uniform density, I think. Then I use a piece of a plastic container lid I cut off convex to get down far enough to evenly chop off. Works well for an even extraction.

[cannonfodder]

I recently did some single shot work on the Domobar Super for the buyers guide. It may provide some single basket assistance.

[Fullsack]

That's impressive. A single shot ristretto is the true test for technique.

[mrgnomer]

That's impressive. A single shot ristretto is the true acid test for technique.

Lots of good advice and research helps along with experimenting and practice. Getting the dose level right is the trick, I find. A day with pretty high humidity helps too

[Fullsack]

The WDT fluffs up the grind for me to avoid overdosing and evens out dose for a more uniform density, I think.

Kirk,
I want to agree with you on this one because what you say makes sense and because I can't figure out the logic behind why my experience is what it is.

Repeatedly, I have been pulling inferior shots when doing WDT longer or faster or deeper in the basket.

[RapidCoffee]

Another thing that may improve results, with further experimentation, is the length of WDT time and the speed with which it is done. I'm convinced that less is more, when it comes to keeping the fluff of the coffee intact, in the filter basket.
...
Repeatedly, I have been pulling inferior shots when doing WDT longer or faster or deeper in the basket.

As you can see in this WDT video, I don't make a big production out of stirring. Just a few seconds to break up clumps and even the distribution, then tamp and pull.

There's been speculation that the WDT causes a redistribution of particles in the basket, with fines migrating to the bottom. This may be a secondary effect, if indeed it happens at all. My current thinking: stirring the grinds not only breaks up clumps, but allows the coffee particles to pack more efficiently (like shaking a jar of marbles). Shaking, tapping, stirring - all of these accomplish the same thing. Naturally you have to adjust your grind and dose accordingly.

If your grinds are already "fluffed", stirring won't fluff them more. But if the grinds are compacted, due to clumping or tapping or overdosing, then stirring can increase the volume or fluffiness. This allows you to downdose slightly by taking a leveled basket, restirring, and releveling. Obviously it won't work if your dose is already too low to reach the basket rim. When downdosing below the rim, I focus more on leveling than anything else.

While it's possible that the duration, speed, and pattern of stirring have an impact on the resulting pour, I've never noticed it. However, the diameter of the stirring implement does seem to matter. Most common kitchen implements (toothpicks, barbecue skewers, etc.) don't work as well for me as a dissecting needle or dental pick.

[CoffeeOwl]

Kirk,
I want to agree with you on this one because what you say makes sense and because I can't figure out the logic behind why my experience is what it is.

Repeatedly, I have been pulling inferior shots when doing WDT longer or faster or deeper in the basket.

What do you mean by saying 'deeper in the basket'? literally putting the needle into greater depth, until it touches the bottom of the basket?

[Fullsack]

What do you mean by saying 'deeper in the basket'? literally putting the needle into greater depth, until it touches the bottom of the basket?

Yes, I think it brings more fines to the bottom. I usually go 2/3 to 3/4ths of the way.

[RapidCoffee]

Yes, I think it brings more fines to the bottom. I usually go 2/3 to 3/4ths of the way.

You could be right, but I'd like to see some evidence of this. Fines supposedly migrate to the bottom of the basket as the shot is pulled, and help control the flow rate. Makes sense, although I haven't seen any data for that either. (Anyone care to start slicing pucks for particle size analysis? ) I'm not smart enough to predict the effect of imposing a particle size gradient in the basket before the shot.

Regardless, I stir all the way down to the bottom of the basket, stopping when clumps are eliminated and the grinds are evenly distributed. I've never noticed any significant impact from different stirring patterns, stir depth, stir duration, etc. Naturally YMMV.

[CoffeeOwl]

I usually go 2/3 to 3/4ths of the way.

That's the message of the day for me!
I noticed that if I stir with the needle put right to the bottom, I may form a hole in the puck in place from where i take it out in the end. I tried with thinner needle, but it didn't help. I'll try stirring in lighter depth.

EDITS:
21.12.2007
I found it very helpful to not stir to the bottom of the basket but less and to do it more vigorously then I used to, to distribute and level the coffee.
Then I use flat knife to do a sweep (but it doesn't sweep anything off with the dose at 15.5g, eventualy only evens the very top of the pre-puck)