tamp

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A tamper is a device used to compact or flatten an aggregate, typically to make it resistant to further compression. Some examples are small, handheld tampers to compress ground coffee into a puck in the preparation of espresso, manual or powered tampers to compact gravel in the preparation of laying a concrete or brick patio or walkway so that the underlying gravel layer does not settle over time, and self-propelled, mechanised ballast tampers, which compact the ballast underneath rail tracks.

Railroad construction foreman Phineas Gage lived for almost twelve years after an 1848 accident which drove a three-foot seven-inch iron tamper ("tamping iron") through his brain.

Coffee Tampers

In the coffee world, a tamper is used to compress grounds into an espresso machine's portafilter. This helps to lengthen the brewing cycle, and thus allowing more of the oils from the ground coffee to enter the cup, providing the intense flavor of espresso.

Coffee tampers come in a variety of shapes, sizes and materials so as to accommodate the different constructions of various machines, as well as the preferences of the barista using it. Some of the more popular brands of tamper include Bumper, Rattleware, and the EP line from Espresso Parts NW. Some baristas will opt to have a tamper custom made for them, many turning to Reg Barber^[1], who has established himself as the leader of the pack in custom tamper manufacturing. While the handles of coffee tampers can matter greatly to the person using the tool, what matters most in terms of espresso extraction is actually the base of the tamper. After picking what size fits the portafilter for their machine (ranging from 49mm for lever La Pavoni machines up to the more common 58mm one will find in most coffee houses)^[2], the barista must pick a base for the tamper. While new styles are constantly being created, the most common choices are between a flat base, or a convex base. There is much debate over what effects the two styles have on the extraction, but there is speculation that the original convex base was created to match the shape of the common single espresso baskets (usually holding 7 to 9 grams of coffee) while the flat was created to match the base of flat double baskets (holding 12 to 16 grams).

Given fresh roasted, uniformly ground coffee, and a good espresso machine, the most important remaining process step controlled by a barista is tamping. Providing a consistent level tamp is very important to making espresso: if your tamp force or angle varies, your shot will vary. Two choices are available for ensuring a consistent tamp: tamping with an ornamental tamper on a small scale such as a bathroom scale or using an automatic 30lb tamper. Increasing the tamping pressure will increase the brew time of a shot of espresso, and thus increase the extraction from the coffee - hence the need to maintain consistency.

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