In august last year I posted a blog about the difference, if any, between flat based tampers an convex based tampers:
http://kostverlorenvaart.blogspot.nl/2014/08/tamper-base-flat-or-convex.html
My conclusion then was that I could not detect a significant difference.
I do like my little effective Londinium Button tamper but I mostly use it to tamp a puck absolutely flat in order to measure the roast color with the Tonino device. For extractions I mostly use the Intelligentsia Black Cat convex. I have ordered the latest Londinium button tamper which allows 'nutating' of the coffee puck so I can't wait to test that.
This morning I noticed a tweet by R. Justin Sheperd reporting a dramatic "mind blowing' difference between flat and convex tampers:
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http://kostverlorenvaart.blogspot.nl/2014/08/tamper-base-flat-or-convex.html
My conclusion then was that I could not detect a significant difference.
I do like my little effective Londinium Button tamper but I mostly use it to tamp a puck absolutely flat in order to measure the roast color with the Tonino device. For extractions I mostly use the Intelligentsia Black Cat convex. I have ordered the latest Londinium button tamper which allows 'nutating' of the coffee puck so I can't wait to test that.
This morning I noticed a tweet by R. Justin Sheperd reporting a dramatic "mind blowing' difference between flat and convex tampers:
I had not thought to test the difference with a refractometer and I have the VSTlabs TDS meter at hand so I set out to see if I can replicate the Sheperd results.
Shepard did not specify his method, what refractometer / app used, what baskets if any different, et cetera.
In my tests, using the LONDINIUM I machine, three different origins were used: Sumatra Mandheling, Peru and Colombia, roasted Tonino # 107, # 116 and # 103 respectively, so all in the "light roast" spectrum, roasted 23 and 26 February.
Each time 18g of beans were ground on the motorized HG One with 83mm burrs, in the same grind setting for both tampers and into the IMS filter basket with size codes B68 2Th16.5 E.
The same naked portafilter used every time.
Preinfusion: 7 seconds every time.
I monitored the extraction time, flow and weight with the Acaia scale.
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| Mandheling and 27mm spanner |
For every shot I used a freshly unwrapped syringe and I used three different filters for the measurements, frequently comparing the same extraction through another type syringe filter to make sure the filter was not causing a significant difference. No difference was seen, just the flow from the original VST filters is much better and they do not easily break under pressure like the cheaper filters do.
Distilled water was used to calibrate the refractometer between each set of measurements.
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| Test setup |
The Sumatra Mandheling had a slow flow, 35g out in 28s with 10.7 TDS yielding a 21.6% extraction for the flat base, 34g out in 48s and 10.7 TDS -> 20.9 % EXT, which is practically identical.
Peru, flat: 35g in 31s, TDS 9.5 -> 19.1% EXT
Peru, convex: 35g in 24s, TDS 9.0 -> 18.1% EXT
Colombia, flat: 36g in 37s, TDS 8.7 -> 18% EXT
Colombia, convex: 37g in 36s, TDS 9.3 -> 19.8% EXT
In the 'flat Colombia' extraction, my distribution was probably a little sloppy as some early 'thin' drops appeared in one spot on the bottom of the filter basket but luckily during the pre-infusion this channel closed. Still a little lower % EXT which I think was caused ore by the early dripping than by the tamper.
My conclusion is that once more I cannot see any significant difference in the results between the two tamper bases.
