A friend and I both have aeropresses that have been through 2-4 years of use. I noticed that mine has what looks like coffee-stained abrasions near the top of the column, furthest away from the filter. This is usually the region where the water surface is at longest, before I end up pressing it. No amount of washing seemed to get rid of the abrasions so they must be baked in to the plastic now. My friend confirmed he had a similar experience with his. Due to the rugged surface, it probably increases the chance of upward-leaks while pressing down on the plunger.

Is this due to some reaction occurring (unlikely I would think), or is it due to heat rising to the top (also seems somewhat unlikely to me)?

Update: Photos

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  • 3
    Hi bbarker, welcome to Coffee SE. Do you have a photo of these stains? Maybe the community can identify them more easily with photos.
    – MTSan
    May 26 '16 at 21:36
  • I know what you're talking about, my girlfriends sister (the person who introduced me to Aeropress) has those scars at the top of her Aeropress. I've been using mine for 1.5 years and don't have the scars yet too. I assumed it was heat related, possibly even the type of plastic used. +1 May 28 '16 at 13:51
  • @MTSan - thanks for the suggestion, I finally got around to doing it!
    – bbarker
    Jun 3 '16 at 14:54
  • 1
    from what I read, Aeropress changed material several times through the years until they settled down, so I'm afraid there may not be a universal answer to this.
    – Thomas
    Sep 29 '20 at 13:45

However I cannot understood the scars definitely, I would like to offer a solution to the scars I thought:

There is a possibility that coffee grounds may stick to the rubber ring and scratch the plastic column when pressure is applied as they stay in between the rubber ring and the plastic column. Still, these scratches do not affect the performance of the gadget if they are not large enough to leak.

Easiest way to clean the grounds is rubbing the surface of the rubber ring by your finger under warm water for a few seconds.

Edit: After I see the photos, my guess is, these scars are caused by the scratches first, then the polished surface of the plastic is peeled off by heat. I assume you may continue to use it without problems. For other people with brand new aeropress, my previous advice still holds: try to wash away residual grounds off the rubber ring.

  • I've downvoted this because it's not an answer with any justification or evidence, just a guess.
    – PJNoes
    Jun 6 '16 at 23:37
  • @PJNoes You're right, it may be noted as well as a comment instead of an answer. I'll try to be more careful next time. Thanks for the remark.
    – MTSan
    Jun 7 '16 at 10:13
  • Still, in fairness, I feel like it was reasonable advice and it might be difficult to get a scientifically acceptable answer :) Which is why I upvoted but didn't accept.
    – bbarker
    Jun 17 '16 at 14:55

A couple years ago I emailed AeroPress because I had gone through two presses with a similar problem. In my case, the cylinder had developed heavy abrasions that affected the plunger seal. Here's my original email and photo attachment from 2014:

I really enjoy the AeroPress, but over the past three years I have had to purchase 2 presses because of damage to the inner lining of the cylinders. After about 6 months or so of use, scratches and then cracks appeared in the cylinder walls.
Attached is a photo of my second cylinder. Even after carefully cleaning it after each use it is now so scratched that it will not allow the plunger to hold a good seal.
Would you be willing to replace my damaged cylinder?

enter image description here

Here is the AeroPress response:

The crazing shown in your photo is a rare occurrence with an AeroPress coffee maker. I know you have been unlucky to have it occur twice but it really does happen way less than 1% of the time. We are working to learn what manufacturing process conditions coupled with certain use conditions cause the problem. Send us your mailing address and we will send you a replacement chamber plus a new seal so we can make sure we get your AeroPress back to working properly.

AeroPress did send me a replacement and it developed the same "crazing" (as AeroPress described) after 9 months. I was going to write to them again, but I had an extra AeroPress that I'd purchased for my son, but he'd never used. I've been using this press for over a year and although it has developed a few scratches the plastic seems to be holding up as I would expect.

Anyway, hopefully this adds a bit to the info/background about this issue.

UPDATE: April 2018

After seven years of using the AeroPress (starting in 2011), it looks like I've FINALLY obtained a durable version that lasts more than a year. My current AeroPress (shown in the photo below) started brewing coffee on 22-MAR-2017 and is still going strong, with NO damage to the cylinder. The cylinder's milky, opaque plastic differs from my four (4) previous AeroPress cylinders, which were all smokey, clear plastic (like the 2014 photo that I sent to AeroPress). All of the smokey, clear cylinders developed abrasions (what AeroPress called "crazing") after 6-9 months of use and all became unusable (not holding any pressure) after 9-12 months.

Nothing about my coffee preparation (using ground Peet's coffee and water heated to the 180 degrees) and clean-up process (wash everything immediately after each brewing) has changed, so I feel confident that something about the cylinder's chemical composition and/or manufacturing process has been modified to cause this positive change. :-)

enter image description here

  • I've seen very similar cracks appear on my oldest AeroPress which is about 5 years old. I'm sure I haven't done anything to scratch it and I'm sure there haven't been any coffee grinds trapped between the plunger and the barrel. I've concluded that it's probably an artifact of the injection molding process where multiple streams of melted plastic are fused. My guess is that there are some weakened planes remaining after the plastic hardens that reveal themselves after hundreds of heating and cooling cycles. No proof, just my best engineering guess.
    – PJNoes
    Jul 19 '16 at 18:24
  • Some soaps with antimicrobial/antibacterial or aromatic additives will cause crazing in plastics.
    – Netduke
    Mar 1 '19 at 21:01

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