Just to confirm what everything points at: that separated grind can stick back together again ... I made this:

Sifted coffee into my usual fractions with 400 and 1100 um

Placed the fines (below 400 um) and middle size particles on a plate under the microscope. Pushed them close together for a "before picture"



Then I mixed the two fractions on the plate with a stick ... and yes the fines easily stick to the larger particles again:



The applied use for this is when you got visual fines in your grind ... then it helps to stir the grind ... to get the fines to stick on the larger particles.

Fines just like to stick - but are easily loosened again.

That might explained a reduction of the mud layer I seem to get with stirred grind

Makes me wonder if WDT might have benefits besides distribution

Navigate wrote:That is exactly what I am thinking: it seems to be a good idea that something is held back - the components that give the over-extracted taste.

Just for clarification I was not suggesting that one extracts from the extracted bits (overextraction). I was referring only to the underextracted mass.

If different grinders leave different masses of underextracted grinds - the yield would be different (albeit the flavor may not be).

May assumption then was that given the higher yielding grinder would leave more behind less brown grinds.....

Affixing the fines the thenlarger particles is normalization. Achieving uniform density. That is what WDT does.

Navigate wrote:Then I mixed the two fractions on the plate with a stick ... and yes the fines easily stick to the larger particles again

If the "where the fines are" theory is correct, and it is possible to reattach them to the larger particles, then a stirred version of your experiment where you recombined the sifted fractions should reproduce the unsifted result, should it not?

jpender wrote:If the "where the fines are theory" is correct, and it is possible to reattach them to the larger particles, then a stirred version of your experiment where you recombined the sifted fractions should reproduce the unsifted result, should it not?

I agree. Have also been thinking about doing that; brew a remix of sifted grind.

Microscopy of grind taken out at bloom stage.
Here a medium-dark roast.

Since I will disturb the particles when spread out .... here a photo from a pile of grind ... just lifted out from the filter.
You can kind of see how smaller particles stick to larger. But "a pile" doesn't give a good view.



And here I carefully picked out a little

Here same grind, just after extraction on V60.

We talked about whether the color would be lighter after extraction ... that's not visible here ... not convincingly.

First photo is from the top layer of the V60-drained-puck


Next photo from the grind near the bottom ... not spread out.

Same thing just with very very light roasted coffee.
The darker roast above is darker than I normally roast. This one is lighter - I have never tried so light before: dumped shortly after First Crack started.

And the sun is directly on the grind under the microscope - that gives the bright color too.

Taken out at bloom:


and .... notice the airbubbles trapped just below the center of the photo:

Same grind after extraction on Kalita (by Malling):