The Prufrockers really love your tamper design. I’ve been chatting with Dave (Prufrock Head barista and Conor’s son) as to how we can make a bespoke service with these. ie. how long the handles are and what wood they are made from. We might also consider the tamper width as many home users will have 55mm diameter bases.
More esoteric considerations might be 0.1mm variations in base diameters though this isn’t too important from a commercial perspective and is widely debated. The main point of contention is that a 58mm tamper, (designed to fit a 59mm basket) leaves an half a mm of uncompressed coffee against the edges. Maybe this isn’t a variable at all. It might be desirable. Make the tamper too wide and it gets stuck or might even create a little suction that can unseat part or all of the puck when it is withdrawn. I have struggled to prevent this with a 58.5mm in the past.
We think a flat tamper base is preferable to convex. The principle behind convex tamps is to guide a little more coffee towards the edges of the basket. The extra bulk should help add a little more flow restriction in the area channels most often occur. I’ve chatted to John Gordon about this and his thinking was that convex doesn’t compress the edges as much as the middle.
We no longer consider the C-Flat and convex designs to be of any benefit in preventing channelling. Channels when they do occur usually flow out through the holes around the outer edges of the basket because water is finding its way between the coffee and the slippery metal edge of the basket. (Coffee water seems more impeded when it travels through grinds locked into grinds rather than grinds resting against polished steel.)
A convex tamp will also tend to swivel a little under load as it is obliquely ball shaped on the base. A flat base with very sheer sides like the base John has sourced you seems to generate more resistance against the grinds and so you have a better sense of when your have tamped flat.
Prufrock has a policy of ‘Vince (Fedele) is always right’ and the VST tamper by Pullman has a flat base and is machined to 58.35mm +-0.5mm so this tells us plenty. Pullman together with Reg Barber certainly seem to be the industry leaders. Pullman has a principle of balance between the weight of the handle and the base. Heavy bases have prevailed historically but if you are tamping 1000 times in a day you might like a lighter base. Titanium? This would help promote balance. The balance principle was established through survey. Read about it here.
The bespoke side of it is mainly to do with height. We can ascertain a customer’s preferred handle length by adding or subtracting washers and then measuring the agreed height from the outer edge of the top of the tamper base to the top of the handle. We teach baristas to fit the handle right into the centre of the palm to reduce pressure on the finger tips. Then the thumb and index finger should be positioned at the outer edge of the top of the base to feel against the filter basket if the tamp is aligned straight in the basket. We could always go small, medium and large but it is preferable to be exact.
The pressure on the index finger and thumb with our prescribed technique is still measurable even with the tamper secured right in the centre of the palm. So Pullman’s rubber section really does relieve pressure beautifully and the John Gordon base being curved is also greatly preferable to a flat surface on the top of the base even if it is angled down towards the edge.
For wood type it would be nice to have some unfinished sample cuts and a lacquered and a satin finish to show customers here in London. Hard wax oil doesn’t seem to stand up too well to coffee tannins and oils over time. It rubs off and becomes grimy.
Easy removal of the handle seems preferable as a barista might choose to fit their own washer to lengthen it. You could consider making a washer or two to accompany a tamper to cover the less fussy end of the market. Home users don’t have the high repetition issues that a professional barista has so optimum length is less critical. It is better to offer it made to measure if we can.
The tamp should be able to withstand frequent un-screwings. A barista will surely play with his/her tamper.
We would like to make a plinth like or sunglasses style display case with a glass lid in the shop to display these so if we had a few on display it would make more of a splash.