another_jim wrote:The TDS and extraction levels that are tastiest vary by coffee, roast and prep method. All you truly need to know is that grinding finer gets you higher extractions; and that higher extractions taste mellower, while lower extractions taste rawer (the mild flavor and body compounds extract last, the strong flavor compounds extract first). You can measure until you are blue in the face and you will learn nothing more than this. Taste the brew, then adjust the grind to taste; and that is all there's to it. The rest is commercial BS and "selling water by the river"

TDS & extraction levels are not obliged to remain constant across different coffees, or methods. This is clearly discussed in the Wendelboe video that inspired this thread. It is not disputed.

Grinding finer increases extraction until it fails to increase it, then it falls if you go too fine. Where water passes in the only places it can, it can overextract some of the grounds & underextract others, the resulting taste may be inconclusive. So we brew, taste, measure, adjust grind, repeat. It is another point of reference.

Andy wrote:Correct, but that doesn't necessarily mean it is inaccurate, only that it is imprecise. I don't know whether such a low-res reading is useful for determining extraction rate. Anyway, I agree with another_jim's approach.

You misunderstand me. I meant that the cloudiness didn't matter much.

Making practical use of an optical refractometer, when you can't dial in by taste:

I and my son-in-law have balances and optical refractometers. He lives 1,000 miles away. He's just getting serious about his espresso, so I have been guiding him in his crafting of shots. The optical refractometer measurements were really handy for advising him on grinding, extraction times, dosing, etc. And a lot of fun for both of us to play with.......

That makes sense. Newbies frequently have a hard time figuring out the setting range for their grinders.

An alternative is using a highly standardized basket, such as the the Strada or VST, at the recommended dose and setting the grinder to get a 30 second shot. That will get you in the range from which seat of the pants adjustments can be made. That still leaves brewing and steeping grind settings; my suggestion there is to start with very wide adjustments and binary search your way to the right range (if you use the link, wikipedia math articles tend to start with "look ma, I know set theory" techno-babble, so scroll down for the rational part).

Jim,

To parse the linked article's relevance, does binary search of values below the 30 second flow rate start by decreasing it a large amount like 6 seconds, than halving the interval to 3 seconds, etc.? You might repeat the same procedure by extending flow rate to 36 seconds, decreasing by 3, etc., until you nail the best shot?

So would binary method be in conjunction with stopping a shot at the blonde point also ...

Oops, I meant binary search as an option for pourover or steeping, because the only information is whether it tastes over or underextracted, and because there is a wide range on workable grind.

In espresso you also know the dose and how it flowed. So once you have an initial grind setting, and you know the dosing range n your basket, you have your usable grind range. The VST-18 and Strada baskets are standardized for 18 gram doses, and that will get you towards the fine grind end of the usable range (although with very light roasts maybe in the middle). If you use any standard Italian basket double, the nominal dose of 14 to 15 grams will be at the fine end of the grind range, singles at 7 to 8 will also be at that range (use the crappy plastic tamper for singles). For non-58mm machines, the supplied baskets at their nominal dose will usually also represent the fine end of the grind range.

IMO, under-extraction in espresso only became an issue because (milk)drinkers in the new, non-Mediterranean espresso countries insisted on overdosing their baskets. If you use the gear as designed, the extractions are almost always fine.

Fine dialing of espresso is def a huge reason to want it, but perhaps even more so is as said above: other brew methods. Varying temperature, roast, steep times and brew methods and grind time can make it difficult to pinpoint optimal adjustments-especially with larger coffee doses

I don't find it a huge reason. If you are familiar with different coffees and roast levels, and if you're familiar with your machine, you can pretty quickly dose by taste. If you're not familiar with these things starting with brew parameters others have posted as Jim did just above can get you there quickly.

another_jim wrote:your way to the right range (if you use the link, wikipedia math articles tend to start with "look ma, I know set theory" techno-babble, so scroll down for the rational part).

Neat! Thanks for the suggestion--my son-in-law's machine is a $100 DeLonghi--seems to be a nice machine for the $$...was worried that I'd need to do optimization: http://en.wikipedia.org/wiki/Mathematical_optimization
(Can see machine learning creeping into espresso making in the future, especially with availability of inexpensive detectors and processors.....)

I use VST and EP HQ baskets--like 'em both. Not sure why they affect my espresso in different ways????? They present the same resistance to espresso machine pumped water and certainly offer a lot less resistance than an espresso puck. Their shapes are different--HQ is kinda conical and VST is cylindrical. Yet they do behave differently for dialing in shots. Wondering if the shape and size of the hole intimately interacts with espresso grounds that partially lodge into these spaces? Subsequently, local constriction of water flow through those holes might have a major effect?????? Square vs. hexagonal hole; jagged vs. smooth, etc...The height of the puck makes a big difference in flow rate and I've read your insightful studies considering such factors.