Adjusting for coffee bean density

#1: Post by **mwynne** » July 31st, 2020, 2:37 pm

I may have missed this in some of the 101 topics - if so, please just point me in the right direction.

For reference, using a Rok GC (would like to replace with with a Cafelat Robot), not using any conventional espresso machines. Am also still pretty new to at home espresso.

I don't have a specific question, but am curious what effect bean "density" has, and what kind of attention it deserves. As a point of reference, my usual dose in the Rok is 16.5g, depending on the beans. With a lighter roast (ground a bit finer), it may only fill about half the basket. With a darker roast (usually a little coarser), the basket can be full to overflowing. I know the difference in grind fineness is a factor in volume, but not the whole story.

So, I guess what I'm wondering is, should I be thinking about the different volume of grounds that I see with different roasts (in addition to grind, weight, pull time, ratio, etc), or is it not really an important factor?

Thanks!

#2: Post by **jpender** » July 31st, 2020, 5:30 pm

mwynne wrote:With a lighter roast (ground a bit finer), it may only fill about half the basket. With a darker roast (usually a little coarser), the basket can be full to overflowing. I know the difference in grind fineness is a factor in volume, but not the whole story.

Grind fineness has an effect on the packing density of tamped ground coffee but it's a lot less than the effect due to degree of roast. Darker roasts are less dense. If you're grinding more coarsely as well that reduces the density further but most of the difference is due to the roast.

mwynne wrote:So, I guess what I'm wondering is, should I be thinking about the different volume of grounds that I see with different roasts (in addition to grind, weight, pull time, ratio, etc), or is it not really an important factor?

It's a good question. Obviously the coffee has to fit in the basket. After that I think it just comes down to the usual process of dialing in the shot. If the dose (weight) needs adjustment, based on taste, then you adjust it. If there is some general rule about down sizing the dose for darker coffee I'd be curious to hear about that as well.