Can someone clarify this for me;

I like to make single shots and have read it stated that on the basis of a standard shot, ie not making ristretto or lungo, single and doubles should take the same extraction time.

Surely given that the single will use half the amount of coffee and produce half the size of finished shot, for this to take the same time, the tamping and/or grinding must be altered accordingly.

for example; - for 14g coffee producing 2oz in 25 secs for a double; then for 7g to produce 1oz also in 25 secs......finer grinding and/or a lighter tamp?

I know there are lots of variables involved but it is the underlying principle which I wish to clarify.

Thanks.

The difference is in the basket design. In theory, the baskets are designed such that the same grind setting should be used for both. The same should be true moving up to a triple basket as well.

In actuality, singles are VERY sensitive to small changes in dose, since a small change is a much greater percentage of the whole. So it can be tricky to get it right. I personally find it easier to do singles with a slightly finer grind than I use for doubles, but ideally the right grind is the right grind and its really the dose you should be adjusting. Your mileage may vary, and as always you should do what works for you.

David,

No. But allow me to explain.

Not true in a commercial setting; there the baristas do not adjust the grind for every shot.

Not true in your home either, or at least not usually. The alterations in taste from loosening and tightening the grind are more consequential than those which come from a few seconds difference in water contact time.

And, as Nate said, baskets designed for singles will restrict the flow rate enough to provide extra contact time, compared to baskets designed for doubles.

Also more significant than a few seconds of contact time are the relative amounts of time for the beginning, middle and end phases of the shot -- each of which has its own distinctive taste. It's really the proportion which makes the difference between ristretto, normale and lungo rather than the amount of the pull.

More specifically, a ristretto ends before or just as the shot starts to show signs of blonding, with the stream still exhibiting a little striping; while a lungo continues well into blonding, with the stream tending towards very pale.

Of course, with a given grind and similar distribution, the amounts between the different styles will vary just as you'd expect -- with ristretto being smallest and lungo largest.

Either way, grind or dilution, the barista uses temperature and degree of extraction to control the flavor profile of the shot. Time is one method of controlling degree of extraction, but only works if "everything else is equal." If you alter grind and quantity to keep time the same, you'll get big "in the cup" changes.

Hope this helps,
BDL

I occasionally enjoy pulling single shots on my La Peppina and Gaggia Factory, and I don't adjust the grind when going between doubles and singles, and the extraction time is about the same (I don't really measure it) but I do adjust my technique quite a bit. For a double, I will typically pre-infuse the coffee for about ten seconds by filling the group with water and applying pressure (or allowing the lever to rise for my spring lever) so that the puck becomes saturated with water without letting more than a drip or two into the cup before pulling the shot.

For a single, this is too much and will lead to over-extracted, bitter coffee. I will either cut the pre-infusion in half or eliminate it altogether. Because you have less coffee in a single basket, there is less mass to absorb the heat of the brew water from the boiler or kettle as well. In the case of the open-boiler La Peppina, my kettle temp is at my desired brew temp via PID, but with the closed boiler Gaggia Factory, it is probably better to start with a cooler group temp for a single.

The single baskets I have are tapered with less hole area to adjust the flow for a single dose.

Click here for Jim Schulman's dosing formula for pulling singles with the same grind setting as a diailed-in double.

Basically, the single dose is a function of the ratio of the hole areas of the double and single baskets.

It won't work for every combination of double and single baskets, but will work perfectly for some and will only need a small adjustment for others.

I use this formula as a starting point and it usually works quite well.

I understand.

Thank you one and all for your very helpful replies.