Add me to the camp that does WDT and tapping and see's no fines in the cup. I've read from numerous sources that fines are mostly stuck, via static, to larger particles, so I am not sure if WDT or tapping would be capable of dislodging them.

I stir vigorously, I tap to distribute and get a level bed before tamping.

I use a VST 18 gram basket, so maybe the hole size has something to do with here. I suspect machine pre-infusion process also might play a role here. A high pressure fast flow during preinfusion, may wash the fines off in a way they come out. No clue, just riffing on guesses.

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.

I do not see this at all. Maybe my grinder isn't producing fines in the same way yours is. It certainly does, (i grind mostly from frozen) but not in enough quantity or size to pass through my portafilter basket. That it happens to you is kind of bizarre to be honest, the entire point of a portafilter basket is to keep undissolved solids out of the cup.

Good luck.

mike guy wrote:That it happens to you is kind of bizarre to be honest, the entire point of a portafilter basket is to keep undissolved solids out of the cup.

Espresso isn't free of undissolved solids even if you're using a paper filter. Some ultra-fine particles will make it through. I think that's normal. I think it's desirable. But it's not surprising that the amount varies. I don't know how representative it is but Illy (p.292) includes an analysis of of an espresso shot and they found that 10% of the solids were undissolved. In a 30g double shot that would be 0.3g of "fines".

I get a little circle of dust-like fines when I prep. And the rim of my cup always has a little ring of debris where the crema was. But nothing large enough to sink to the bottom ever makes it through.

I have noticed some fines on my mat (where I WDT, doze, and tamp) after a session of espresso making, but I would imagine all espresso has fines in it. You've gone to top level baskets so that would be the best you could do unless your grinder just makes way too many fines. I have to wonder if it matters? How does it taste? Something tells me espresso would not be espresso without fines.