I recently had a minor breakthrough with my espresso recipe that I wanted to share with you guys.

I've been struggling a bit with grinds in the cup for a quite a while. I did a lot of research and tried every suggestion I could find short of upgrading my grinder. I even tried switching from ceramic to steel burrs in my Vario. The general consensus seemed to be that the fines were not passing through the basket but rather getting stuck to the bottom of the portafilter during the grinding and tamping process. But I was meticulously cleaning my scale and tamping surface and even wiping the bottom of the portafilter just before pulling a shot. Nothing seemed to help much at all.

I had pretty much given up, but I think I recently stumbled on the solution. I noticed that if I don't use the Weiss distribution technique I get fewer fines in the cup. My theory is that stirring the grinds redistributes the fines towards the bottom of the puck and makes it easier for them to get pushed through the basket into the cup. I don't know if this is only a problem for relatively inexpensive grinders like my Vario, but it seems to make a pretty significant difference for me.

Now I'm just using a very light, shallow stir to flatten the mountain of the grids before using a distribution tool and tamping. With this technique, I'm getting fewer particles in the cup to the point where it's about on par with a shot from a quality coffee shop. It seems to have toned down the bitterness a bit too.

Has anybody else noticed this connection between WDT and fines in the cup?

Has anybody else noticed this connection between WDT and fines in the cup?

Yup. I quit doing WDT ages ago on account of a post here in H-B. The post said that one should not tap the PF, as this caused the fines to drop to the bottom of the basket. A light went on in my head and I jumped to the conclusion that the output of my grinder was an amorphous mix of various particle sizes. The more I messed with it, the more likely it was to become stratified. The fines would drop to the bottom and the coarser bits would rise to the top. I had not really thought about your point of the finer fines getting into the cup, but it's inevitable. Of course, a lot would depend on the particle size distribution of the grinder. But, I have never had a multi-thousand dollar grinder; so I can easily accept that I have some fines small enough to pass through the holes in the basket. I suppose that the basket being used would also affect this to a degree. I switched to a competition basket, which is supposed to have precise holes--not sure if they're smaller though. Instead of WDT, I now do a longer pre-infusion to let the puck bloom, which I believe results in less tendency to channel, both along the edges and through the puck.

I did notice rapping the portafilter can cause some fines to fall through, but never thought it could be attributed to WDT. WDT improves my extraction evenness in general so it's rare that I pull a shot without it.

In my experience, another major factor for the fines seems to be the basket that I use. From my observation, some baskets have larger holes that allow more fines to go through. What basket are you using?

Nunas wrote:Yup. I quit doing WDT ages ago on account of a post here in H-B. The post said that one should not tap the PF, as this caused the fines to drop to the bottom of the basket. A light went on in my head and I jumped to the conclusion that the output of my grinder was an amorphous mix of various particle sizes. The more I messed with it, the more likely it was to become stratified. The fines would drop to the bottom and the coarser bits would rise to the top. I had not really thought about your point of the finer fines getting into the cup, but it's inevitable. Of course, a lot would depend on the particle size distribution of the grinder. But, I have never had a multi-thousand dollar grinder; so I can easily accept that I have some fines small enough to pass through the holes in the basket.

samuellaw178 wrote:I did notice rapping the portafilter can cause some fines to fall through, but never thought it could be attributed to WDT. WDT improves my extraction evenness in general so it's rare that I pull a shot without it.

I actually have been doing one light tap of the portafilter on the counter after stirring to knock any residual grinds down off the dosing funnel into the basket. I suppose that could also be another contributing factor. I did briefly try skipping that step in the past and didn't think it made a difference. Maybe I should play around with it some more.

Nunas wrote:I suppose that the basket being used would also affect this to a degree. I switched to a competition basket, which is supposed to have precise holes--not sure if they're smaller though. Instead of WDT, I now do a longer pre-infusion to let the puck bloom, which I believe results in less tendency to channel, both along the edges and through the puck.

samuellaw178 wrote:In my experience, another major factor for the fines seems to be the basket that I use. From my observation, some baskets have larger holes that allow more fines to go through. What basket are you using?

I have 18g and 20g VST baskets. Currently using the 20g basket for the extra headroom. I believe the 18g basket has slightly smaller holes, so that could help in theory. I haven't done any back to back testing, but I can't say I've noticed a difference in the amount of fines between these two baskets. I'm not sure how the size of the holes compares to other brands.

I use pretty vigorous WDT and also a couple of light taps, and I have no visible fines in the cup. I don't know what the difference may be or what to suggest though.

I've been stirring grinds as part of puck prep for over 14 years. During this time I've used many different grinders, machines, and baskets, and never had a problem with fines in the cup. Not once. Unless you've got grinds sticking to the bottom of the basket, I'm not sure how this can happen. The puck itself acts as a pretty good particle filter.

How significant is the Brazil nut effect when you stir dry coffee grounds for a few seconds? IMHO not very. Until someone provides solid evidence of fines migration (e.g., slices pucks and performs particle sizing), I'll have a hard time taking this hypothesis seriously.

WDT is basicly to mix finer/larger coffe particles to create a more homogeneous puck while destroying clumps. Until you are doing this with an hydraulic press, I don't see how fines can get through the basket. Fines and fines migration have a limit, and this limit is the bottom of the basket.

I would suggest to stop WDT, making coffee or using anything related to it for a couple of minutes and clean the area.

I haven't seen anything like what you describe and it seems highly unlikely that brief WDT is enough to move the finest of fines to the bottom of the PF...those fines quite are static and will cling to larger particles and even if they are moved your WDT will not likely do much to separate them unless using a sieve is part of the routine.

Renegade wrote:WDT is basicly to mix finer/larger coffe particles to create a more homogeneous puck while destroying clumps. Until you are doing this with an hydraulic press, I don't see how fines can get through the basket. Fines and fines migration have a limit, and this limit is the bottom of the basket.

I would suggest to stop WDT, making coffee or using anything related to it for a couple of minutes and clean the area.

I assure you no grinds are stuck to the outside of the portafilter. If you don't believe that fines can pass through the basket, just try grinding a dose into a naked portafilter and knocking it on a clean spot on the counter a couple of times. It leaves a light circle of fines on the counter.

WDT is basicly to mix finer/larger coffe particles to create a more homogeneous puck while destroying clumps.

While I agree that WDT will break up clumps, I'm not sold on the notion that it mixes the finer-larger particles into an amorphous or homogenous mass. As I mentioned earlier, I believe it does the opposite. The fines will head down and the larger particles up. I suspect the longer the WDT the greater the effect. When this came up in another thread, I posited that if tapping was good, then why not a little vibrator. One response was that doing either sends the fines to the bottom and the larger particles to the top. When I thought about it, I concluded that this was probably right, as I'd observed this on a vibe table in a lab once, but had not really thought about its application to coffee. So, I wonder if the WDT technique works not by making an amorphous mass, but rather because it sends the fines down, where they create a finer filtering action, especially when wet.

As for the OP's assertion that fines can come out of a basket, I reiterate my reaction--yup. But I stand by my assertion that it probably depends on the grinder. The coffee coming out of a grinder is not one uniform particle size. It comes out like a bell curve, with a range of finer to coarser. I suspect that a really good grinder has a tight bell curve and that a crummy one has a broader curve. With a tighter curve there'd be fewer fines and thus less of it coming out.