Fast shots after trying Andy Schecter's paper filter tweak.

#1: Post by **bettysnephew** » January 4th, 2017, 10:30 am

I was perusing some older posts and saw a video by Andy S. that showed him placing a filter in the bottom of his portafilter. I have always placed one on top of the coffee to keep grinds out of the head. After placing a filter under the coffee and still putting one on top my shots are much faster than before. I have been turning my Kafatek Conical to finer grinds but am still not quite dialed into the 30 second mark. I am quite surprised by how much faster the water flows through with the filter beneath the puck. The espresso is improving as I grind finer but is this a normal reaction to placing a filter under the coffee?

#2: Post by **TomC** » January 4th, 2017, 11:40 am

I believe he commented somewhere that he wasn't the first to try this out (a paper disk at the bottom of the basket) but he was the first to note that the EY increased.

There was some interesting dialogue going back and forth here that sorta died off. I think several people toyed with it, but it wasn't an approach that I've read anyone sticking with (maybe with the exception of Andy?). There was some interesting speculation on what's causing it. Basically, most surmised that the holes weren't seeing as much restriction to flow since fines weren't migrating in the same way as they would without the paper. That's probably pocket science, but it certainly seems believable. Hopefully more people will chime in now that you've brought it back up. It was an interesting thread.

#3: Post by **RapidCoffee** » January 4th, 2017, 11:52 am

The last time I played around with paper-filtered espresso was almost 6 years ago. The primary motivation back then was reduction of cafestol and other cholesterol-increasing oils, not extraction yield. I do not recall any noticeable increase in flow rate, but it was a loooong time ago...

#4: Post by **randomorbit** » January 4th, 2017, 12:07 pm

My guess would be that paper restricts flow less than coffee thus by putting a layer of it between the coffee and the holes, you're actually creating a channel.

January 4th, 2017, 1:20 pm

Clarify, please. This does not compute...

January 4th, 2017, 1:37 pm

Makes some amount of sense. The coffee will still have to go through the basket holes, which are now underneath the filter. If the path of least resistance is not directly through the filter, but around and underneath it, that could effectively cause some back pressure and channeling. Not saying that is what is happening, just potential explanations. I don't think you can automatically assume the solution will travel through the filter evenly.

#7: Post by **randomorbit** » January 4th, 2017, 1:40 pm

RapidCoffee wrote:Clarify, please. This does not compute...

If the paper restricts the flow less than coffee would in the same space, then putting the paper between the coffee and the holes allows water to flow across the bottom of the basket more easily with the paper in than without. Without the paper there, water has to flow through grounds to the nearest hole, but with it, it flows through paper to the nearest hole, and it flows faster through the paper than it would the grounds. I think of it a lot like the ridges incorporated into pour over baskets. If the coffee was right up against basket, water could only flow out where there is a hole, but by lifting the coffee away from the surface of the holes, it creates an easier path for the water to flow to the holes. Additionally, if the path is easier along the sides and out the bottom, there may be channeling where the water mostly goes around the puck instead of through. I am not sure if either or both of these things is actually happening, but it seems a plausible theory to me.

#8: Post by **RapidCoffee** » January 4th, 2017, 2:16 pm

Sorry guys, this seems very unlikely to me. The paper filter is pressed against the bottom of the basket with 9 bars pressure. Why would water flow around the outside and under the paper? And why would you assume the paper filter presents less resistance to flow than an equally thin layer of grinds?

BTW, I saw no evidence of channeling when I tried paper filtered espresso. The major effect, as noted in the thread linked above, was smoother crema. Most likely explanation: large bubbles break up as they pass through the layer of filter paper.

#9: Post by **h3yn0w** » January 4th, 2017, 2:29 pm

Length and speed of preinfusion/ramp up to full pressure will have a big impact on the speed of flow through the rest of the shot. My best guess is that having two paper filters if altering the length and speed of your preinfusion and pressure ramp up.

#10: Post by **shawndo** » January 4th, 2017, 2:38 pm

RapidCoffee wrote:Sorry guys, this seems very unlikely to me. The paper filter is pressed against the bottom of the basket with 9 bars pressure. Why would water flow around the outside and under the paper? And why would you assume the paper filter presents less resistance to flow than an equally thin layer of grinds?

I think it makes sense if the fibers of the paper are larger than the fines of the coffee. If the paper fibers are keeping the fines from clogging/restricting the holes. Same reason you get faster flow when you take out the fines.
Water flow through the paper though. Not sure where the idea of it going outside/under/around the paper came from.