There Are Pandas, and Then There Are Pandas.
And this isn't either of them! The Pandas we're talking about here, are watches, not bears. And what got me thinking about them (again) was a link posted this morning by @cm.rook who pointed a few of us to the very attractive (and not terribly priced) Yema "Rallygraph" Panda which, in it's most traditional arrangement, looks like the one on the left, but can also be had in the version on the right: The model on the left is a true Panda, while the model on the right is called a reverse Panda. The reason for that distinction is clear--Panda bears, only come in the first arrangement. Now at this point, everyone should be thinking about the most well-know Panda, The Rolex Panda, which is actually a Daytona, and among Rolex Daytonas, the most famous of which is the Paul Newman Daytona, which was famous first, because it was Paul's, and second because it sold at auction for $17.8 million (US Dollars). The story of that auction is well-known so I'll only...
Nov 8, 2019
Don't get me wrong, I use an Aeropress daily to brew my home-roasted, freshly ground coffee beans. I love the strong coffee it can produce, but it is not making true espresso. And I am not just being a stickler about definitions, the taste of the strong coffee is not even close to the taste of true espresso.
What pressure am I referring to? The Specialty Coffee Association of America (SCAA) defines espresso as “a 25-35ml (0.85-1.18 fl oz) beverage prepared from 7-9 grams (0.25-0.32 oz) of coffee through which clean water of 195°-205°F (92°-95°C) has been forced at 9-10 atmospheres (128-142 psi) of pressure, and where the grind of the coffee is such that the brewing ‘flow’ time is approximately 20-30 seconds.”
1) Minimum brewing chamber pressure = 128 pounds per square inch. The Aeropress's cylinder is 2.25 inches in diameter, so the surface area of the flat plunger is 4 square inches (pi*R^2). Which means we have to sustain at least 4*128 = 512 pounds of force on the plunger for 20 - 30 seconds of fluid flow to make espresso.
2) Assuming: a) we can apply this amount of force (hire a sumo wrestler to balance on top of the plunger, or put the Aeropress under one side of a teeter totter near the middle while we sit on the the tip of that same side, or something) b) 128 psi is the minimum pressure needed to open the Prismo's valve for steady flow c) the Prismo's seal to the Aeropress holds at least 128 psi without leaking d) the Aeropress's plastic cylinder wall can handle at least 128 psi without bursting Then the Aeropress's sliding rubber plunger seal needs to handle at least 128 psi without leaking.
I know from personal experience - my own as well as others - that this plunger seal leaks during normal use (Maybe up to 40 pounds of plunger force? So 10 psi.) after a few years. So I am certain even a brand new plunger seal cannot handle 128 psi.
But with its unique higher-pressure valve and fine metal filter, the Prismo just might make a higher-pressure coffee beverage that differs positively from that made using a standard Aeropress.
Do you know of anyone making videos on the hydraulic press channel that is looking for more things to try? It would be an interesting way to find out how much pressure the current seal can hold. I mean, if they want to do it, I'd watch the video.
Amazon also list three others for $60 or less, but I'm skeptical any of them reach the required pressure (9 atmospheres/128 psi minimum by SCAA definition).