Is a Bottom Paper Filter Useful?

Beginner and pro baristas share tips and tricks for making espresso.

#1: Post by OK31 »

I know this has been discussed just can't find the discussion. For one reason or another I decided to try a port filter on the bottom of my PF and I must say from the 3 shots pulled it's almost eye opening. I know it removes oils and possibly the beautiful tiger striping although that part may depend on the coffee? What I did find is the most even extraction where the stream comes together in just a few moments and is consistent throughout.

It also seems to make the crema super saturated and even in color. The flavor feels more clean which I'd expect. Not sure what if any negative there is except for yet another pet to the already long puck prep. My current process is : grind into PF, WDT with a homemade tool, OCD, tamp with LM convex stock tamper.

I've watched some videos of top and bottom filters and completely understand the top and cleanliness vs bottom and impact to extraction but is it worth it from findings by those who have done it?

Before I invest in a puncher or some precut want to make sure I'm not crazy or alone.


#2: Post by GDM528 »

Not a complete list:
Can bottom filters improve flavor by reducing crema bitterness?
Puck paper purveyors?
Paper filter in the middle of the puck
Filter paper shot forensics

I've been a fan of top & bottom papers for many months, with no plans to stop. A big win for cleanliness, and whenever I drop in a mid-puck paper, a nearly channeling-free shot. Biggest issue for me is sourcing cheap, drop-in papers - I have to make my own from AeroPress papers. There are lab-grade papers very close to the right size, but $$.

I still get plenty of oils on the top of the shot when using a bottom paper. Adding a bottom paper will change the puck resistance and alter the shot dynamics, which in turn might initially look like a different shot, but after months of practice I seem to have made whatever small adjustments were needed to get back to pre-paper results (minus the fines).


#3: Post by kidloco »

I use them for anything lighter than medium-dark. My only dilemma is whether I should bother prewetting them or not.

OK31 (original poster)

#4: Post by OK31 (original poster) »

So paper on top sounds like similar to a flair 58 idea which though I haven't tried seems to have more to do with cleanliness and maybe water distribution than the physical extraction. The bottom seems to be doing some level of filtering and helping with at least even flow out. I saw the one forensic thread and that's interesting that the extraction can be checked but I wonder how 3 shots back to back would look? To me the taste is definitely cleaner. Similar to when I use a gold or paper filter with drip. Have you noticed any viscous differences in the body?


#5: Post by GDM528 »

"Flair 58" = one of those fancy mesh filter inserts? I prefer the paper filters, which get tossed out with the spent puck. So, no extra cleaning and/or leftover residue from the previous shot. They're only two cents per disk. The primary hassle (and it's a big one) is cutting the disks.

There is a subtle difference in mouthfeel, but I consider it way below all the other shot attributes. I'm skeptical the paper has much of an effect on the flow rate - at least for AeroPress paper. I think other people have posted that the scientific-grade papers can increase flow resistance.

Re: wetting the paper, I wet the bottom paper just so it will stay put when I stir and level the grind. Another reason to pre-wet the paper, is to rinse out any residue from the manufacturing process.

OK31 (original poster)

#6: Post by OK31 (original poster) replying to GDM528 »

Yes those mesh reusable. After watching some videos sounds like it is in fact more effort than needed and adds more work without a full reward. The only thought would be to eliminate the need for cutting which is a pain. Imagine if I got a hole puncher it still wouldn't work given the aero press papers would just get pushed down. On a thread I just finished lead by your others is the suggestion of an e&b super fine ims baskets. That has peaked my interest as I was wondering why if this is a thing has no one capitalized on this little niche even if it's for a small group. For me, the most important thing and I'm finally realizing it has to do with coffee and a bit water is to get rid of sour/acid. I'll take bitter over that as you can dilute bitter but sour just gets less so yet still stays. I'm going to stay with the paper for a bit maybe until I use up the lot and see what happens. Haven't tried the top yet for exactly same reason of cutting. Would love it if we can find a better way to cut.

Lab papers seem like a science experiment I'm for one not ready for but then again when I got into this 4 years ago I didnt see myself with an ocd, wdt self made rake, and all the other little things that friends think I'm crazy for doing.


#7: Post by p4lxrich »

For me I do find that I can grind finer and it definitely helps filter out the fines.


#8: Post by boren »

OK31 wrote:Before I invest in a puncher or some precut want to make sure I'm not crazy or alone.
I bought a puncher from Amazon and it doesn't work well on filter paper, leaving at best an imperfect circle, and at worst not cutting it completely (regardless of the amount of pressure or speed I use). It does work perfectly on printer paper. Personally, I gave up using it and just buy precut filter papers. At 7 to 10 USD for 600 pieces, I think the price is fine. It's negligible compared to the cost of beans and other equipment upgrades.

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#9: Post by RTOBarista »

I get the EPF paper from Weber, $7.50 if you buy 100 and $60 if you buy 1000. I have them both for the 58 mm basket and for the Unifilter. They stay in place for RDT without wetting.