VST basket size and grind volume are at odds

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BrainZaps

#1: Post by BrainZaps »

I find myself using less coffee for VST (20g) basket recommendations and getting better shots. This confuses me.

I find it odd that VST lists a basket size by weight, when the volume can change dramatically while dialing in the grind size. For example, with a dark french arabica, the VST (20g) works fine; but with a medium roast (Lavazza Dek), I find the VST recommendations are off by 10% in order to get something that isn't wildly over extracted (e.g. 60 second shot time!).

I realize it is impossible to spec ground coffee volume, but since the basket varies by volume, this seems at odds.

I'm using a Profitec Pro 500.

Any thoughts on this, other than "do what works best for you"? I'm new to this, I've only pulled about 360 shots (4 a day for about three months) but I've only used two different types of beans.

baldheadracing
Team HB

#2: Post by baldheadracing »

BrainZaps wrote:"do what works best for you"
You've got it 100% right!

The size recommendation is just that - a recommendation. The recommendation might be stronger if you were using the same kinds of commercial machines and the same kinds of blends that were popular when the baskets were developed, but it would still be a recommendation. VST can't account for the differences in how much headspace is available with the domestic group used in a Pro300 vs. an E-61 vs. a LM, etc.

Also, it isn't clear to me - are you using the same grind setting for both coffees? Decafs typically need a finer grind.

Enjoy the journey!
-"Good quality brings happiness as you use it" - Nobuho Miya, Kamasada

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another_jim
Team HB

#3: Post by another_jim »

The VST baskets are a set. The 22 and 20 gram baskets are for coarser grinds and darker roasts; the 18 and 15 gram baskets are for finer grinds and lighter roasts. In essence, if you like this approach, look at the roast color of your coffee and use the appropriate basket and grind. Nordic roasts? 15 gram basket. Neapolitan espresso? 22 gram basket.

Conventional baskets can use a wider range of grind sizes and dose; so are more flexible. But it may be that the right size VST basket for a given coffee can be dialed in more accurately.
Jim Schulman

zefkir

#4: Post by zefkir »

I wouldn't attach excessive importance to what VST says about the grammage of their baskets. I would just consider it as an indication of the maximum grammage the basket would accept. And even then it heavily depends on the roast level (dark roasts take more volume), on the origin of the bean (high grown beans are denser), on the uniformity of the grinder and a handful of other factors.

If after tamping, your puck doesn't touch the shower screen and has a little margin to account for swelling, you can pull a delicious shot regardless of the basket's advertised grammage.

VST's larger basket are slightly higher flow, and it takes maybe a second or two more times to fill the headspace (so some added pre-wetting), so you end with a different dial as pulling 15g in a 20g basket vs pulling 15g in a 15g basket, and because the grind size is a little different, they won't be the exact same shots.

But all in all, it's a rather minor thing. Different coffees, different grinders, end up dialed differently anyway, why not different grammage baskets.

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cafeIKE
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#5: Post by cafeIKE »

zefkir wrote:VST's larger basket are slightly higher flow
Are there specifications to support this?

baldheadracing
Team HB

#6: Post by baldheadracing » replying to cafeIKE »

Here's some evidence from over a decade ago:
Image
- from How filter baskets affect espresso taste and barista technique
-"Good quality brings happiness as you use it" - Nobuho Miya, Kamasada

zefkir

#7: Post by zefkir »

cafeIKE wrote:Are there specifications to support this?
There's an entire section in the following document about the need of matching total cumulative hole area and hole size to he dose, and larger doses needing baskets with more total cumulative hole area ie. higher flow.

http://cdn.shopify.com/s/files/1/0092/7 ... so.pdf?134
Given that most professional-grade hardware these days is generally capable of providing extraordinarily consistent temperature, pressure and flow, there are three other crucial factors that significantly affect extraction flow rates (i.e., contact time and extraction yields): particle size, coffee depth and total cumulative open area in the filter. There is a relationship between these three attributes that must be harmonized for each filter capacity. A filter with correct hole size and total open area designed for 21-22 grams will not and should not be expected to extract normally when filled to only 14-15 grams. It will pour too fast, causing you to try to throttle flow by grinding finer. The problem is that the holes and total open area are sized for a bed depth of 21-gr, so grinding the coffee finer without also reducing the hole sizes will in effect de-tune the filter. The non-dissolved brew solids component will spike, and you'll over-extract the coffee, providing both a bitter and chalky final beverage.

Similarly, if a filter has a large quantity of holes that are too large for its design capacity, then the barista is forced to grind finer to throttle flow, even when filled to normal capacity. This will inevitably produce a similarly over-extracted, sediment-loaded and unacceptable beverage. If a filter has a substantial deficit (too little open area), the barista is forced to grind too coarse, causing faster pours and reduced particle surface area to extract from, and results will taste sour and will measure under-extracted (Fig. 7, 6-10).]
And then in the conclusion, he says he designed the VST basket to fulfill that objective. As far as I know, the precise specifications aren't published.

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cafeIKE
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#8: Post by cafeIKE »

Yes, I've read that...

However:
  • no coffee beans are 100% consistent from dose to dose
  • a single bean varies the dose by about 1% in 17.5g
  • basket holes wear continuously. At what point does one bin the basket? Or does it take n shots to break in a la racing engines?
There are always going to be roasts that pull well in one basket brand and not so well in another. In the decade plus since the basket claims were made, competent shops pull no more consistently than they did previously. In a lifetime of espresso drinking, back to back identical shots have yet to materialize.

lessthanjoey

#9: Post by lessthanjoey »

cafeIKE wrote:Yes, I've read that...

However:
  • no coffee beans are 100% consistent from dose to dose
  • a single bean varies the dose by about 1% in 17.5g
  • basket holes wear continuously. At what point does one bin the basket? Or does it take n shots to break in a la racing engines?
There are always going to be roasts that pull well in one basket brand and not so well in another. In the decade plus since the basket claims were made, competent shops pull no more consistently than they did previously. In a lifetime of espresso drinking, back to back identical shots have yet to materialize.
I have no problem making back to back shots that pull essentially identically based on charting on my Decent, and are not blind distinguishable. Back to back variation is solvable.

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Jeff
Team HB

#10: Post by Jeff »

I do agree with Ike's oft-made point about VST and similar baskets not providing "dose independence" simply by swapping baskets, which was suggested by VST's marketing many years ago (and still might be present). This is a "myth" that seems to have been perpetuated.

Marketing claims and myths (desires?) aside, for many people there is more than sufficient evidence to believe that VST, some IMS, and perhaps other baskets are "high flow" compared to other "precision" and conventional baskets.

I believe this thread was around if the "basket size" of a VST and the volume of coffee grinds were always consistent. I think there's general consensus that the answer is "no".