Posted Wed Mar 1, 2006, 10:02pm Subject: Re: The Aeropress gets metalized...
Barry wrote.
"Alan--are you listening?"
Yes Barry, I am listening.
Mark wrote.
"Alan's not a fan of these filters; he has concerns about LDL cholesterol (which I don't share, but everyone's opinion is important), and this is why he's not actively marketing these filters at this time."
Actually, I've explained in the post below that I tested metal-filtered brew on a lot of tasters and they all preferred paper-filtered brew. I didn't learn about the elevated LDL cholesterol effects of drinking metal filtered coffee until AFTER we'd gone along with the taster's preference for paper. See:
But I am listening. I've just sent metal filters to two other testers. After further feedback we can decide what to do.
Here are a few things to consider:
The filters I sent are about .005" thick, and the rule of thumb is that minimum hole size is equal to thickness. So we could try .003" thick and .003" holes if greater flow restriction is desired.
We can increase the spacing between the holes. In fact, I have one now, which has .020" spacing and .005" holes. This will also restrict flow.
How are you cleaning the filters? I found that some of the holes plug with coffee. Brushing cleared most holes, but not all. This is a potential annoyance.
We already have AeroPressers calling us and asking for a replacement cap after ejecting the puck AND cap into the trash. So Mark, remember to remove the filter from the end BEFORE you eject the puck.
Posted Wed Mar 1, 2006, 11:03pm Subject: Re: The Aeropress gets metalized...
Hello again,
I have some more thoughts on metal filters.
Metal filters are more open than the 32lb paper filters furnished with the AeroPress. As I've written before, there are more open paper filters. Here are some possibilities:
Cupcake drip filters are thinner and slightly more open.
The thin paper used for teabags. You can buy empty bags of this material from vendors who cater to loose tea lovers. I have a box of 40 such bags sold by Melitta.
Even more open "paper". I have some spun synthetic fiber media which is extremely open. I'll test some of it and, if it works I'll pass it along to some tasters.
The open papers could be discarded and wouldn't need the cleaning that metal filters require.
Posted Thu Mar 2, 2006, 12:22am Subject: Re: The Aeropress gets metalized...
I for one am very pleased to see those metal filters. If I could just get some for my Yama I'd be really happy! Good luck with the product --- I had the chance to sample several brews the other day using cloth and paper filters and was interested enough in the product to want to check it out again.
It's wrong to call the coffee "espresso" though, and in the long term this will hurt your marketing efforts (but in the short term it will help move product, so there's the rub). I think you need to start developing a very solid and detailed marketing and business plan because this product has a pretty interesting market potential.
Posted Thu Mar 2, 2006, 7:19am Subject: Re: The Aeropress gets metalized...
Great to see the buzz here.
I'm dying to know what happens when someone "tamps" a fine grind on top of one of these filters, pours in the water, and does a hard press. ;-)
No, I don't expect espresso. But it would certainly be a different kind of extraction than the immersion that serves the Aero so well. Just something I'd like to try!
I'd suggest to Alan that, yes, varieties of metal filters be fabricated with different specs, and tried by willing parties (hehe . . . as if anyone here isn't a willing party ;-)
Something to consider: I suspect larger hole sizes that are easier to clean would be possible if a larger grind was used, but the proven observation above is that this results in "wash-through" as I'm going to call it from now on. Wash-through is a possibility wherever the native Aero immersion extraction method is used with a coarse grind, and this effect is exacerbated with larger filter porosity (whether paper or metal). I'd suggest, therefore, that a "tamped" extraction method be tried with larger grind and the larger metal holes. This will eliminate wash-through; the question would be whether tamped extraction is a sane procedure with the Aero; it would introduce issues (tamp pressure, more sensitivity to grind level, channeling worries, and so on) that might make Aero use much more complex. I think one of the AeroPress's virtues is how bloomin' simple and pleasant it is to use (it's functionally "elegant," if a bit "geek" in its aesthetics), and here I am complicating the heck out of it.
Only partly in jest, I'd say that a "tamped" extraction is a form of full immersion -- only the immersion is "in serial, not parallel." ;-D
BTW, after rinsing regular filters, I mount 'em back in the Aero and set it in the sink's dish drainer thing. I then pour in whatever spare hot water I have left, and let it drain through. This does a pretty good job of rinsing out anything that oils that might otherwise get acrid in the filter.
Posted Thu Mar 2, 2006, 9:19am Subject: Re: The Aeropress gets metalized...
Hi rasqual,
People in the filter world have a term "cake filtration". That's when a layer of particles builds up a "cake" which filters subsequent particles.
The action in the portafilter of an ordinary espresso machine is a prime example of cake filtration. The holes in the basket are pretty large, but the cake stops much of the particulate from reaching your cup. You could emulate this with tamping in the AeroPress, as you've suggested, but giving up the highly efficient extraction which ocurs during stirring is a very high price to pay. Here's an alternative.
Start out the AeroPress process with the standard stir, but then press hard on the plunger for the first few seconds to form a cake. This might prove desireable with metal. You could also try this with your French press. It should reduce the sludge in the cup.
I'll be testing some thinner paper materials in the next few days and will report results.
espressoperson Senior Member Joined: 9 Jul 2004 Posts: 114 Location: Philadelphia Expertise: I love coffee
Espresso: Olympia Cremina Grinder: Mazzer Mini Vac Pot: Cona Drip: Press Pot Roaster: Hottop
Posted Thu Mar 2, 2006, 3:47pm Subject: Re: The Aeropress gets metalized...
MarkPrince Said:
But in one cup - my very first (well second) use of these filters, I got something that I bet would stand up to the Clover, and definitely shine against press and vac pots. The thing is, I tried the Tegu two days ago in a press and was disapointed that the more delicate blue / blackberry notes seemed gone. And now they're back.
So how does aeropress (metal or paper or whatever) compare to press pot? Vac? Americano?
(... vaguely recalling sage advice on this very website (by this very same poster?) about the danger of gushing reviews after too short an ownership period ...)
Posted Thu Mar 2, 2006, 9:08pm Subject: Re: The Aeropress gets metalized...
Experiments with filters
First I tried teabag-paper, which is much freer than coffee-filter paper. The brew seemed identical to that made with our standard filters.
Next I made three shots with filters which are even freer.
Spun polyester, slightly tighter than #3. below. (#2010)
Spun polyester, slightly freer than #3. (#2005)
Metal, .020” spacing, .005” holes. This filter had been cleaned carefully with hot water and a brush after prior shots. It has never been exposed to soap. I put this metal filter on my tongue and it was absolutely tasteless. It’s made from the same stainless-steel alloy that our forks and spoons are made from
All were brewed with two scoops (24 grams) coffee and 110 cc water at 180F. The resulting brew was about 90cc at Brix=5. However the extraction levels were about ten to fifteen percent lower that we achieve with our standard filters. I attribute this to slightly greater drip-through.
After each shot, I ran exactly 30cc (about a third) of the brew through our standard paper filter to trap and examine the particles. You can see the trapped particles in the top row of the attached photo. If I had filtered the entire 90cc of finished brew, there would be about triple these amounts of particles.
I tasted them at espresso strength (Brix 5) side-by-side with, and without, the second filtration. The taste differences seemed small to me, but the samples, without second filtration tasted slightly more medicinal or “chemical-like” to me.
I also conducted a blind test on my wife with two Americanos, diluted from the metal filtered shot. She reacted very negatively to the metal-only sample and said it had a bad chemical taste compared to the same shot which had been filtered a second time to remove the particles. My own tasted buds found far less difference between the two samples.
Regardless of taste, these experiments suggested that the spun polyester filters pass about as much particulate as the metal filters. So they offer another option for people who want to try less filtration.
I await additional feedback from Mark, rasqual, and Colin, who have metal filters.
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