alt.hn

1/29/2026 at 6:04:45 PM

Coffee as a staining agent substitute in electron microscopy

 https://phys.org/news/2026-01-coffee-agent-substitute-electron-microscopy.html

by PaulHoule

2/1/2026 at 5:41:45 PM

I don't really understand how coffee, lacking heavy metals, can effectively give contrast in the electron microscope. I can't access the paper but the available parts didn't seem to explain how this works.

by s0rce

2/2/2026 at 9:43:46 PM

Even without any heavy metal staining, you would end up seeing some structures. This approach allows looking at unstained / native tissue.

by seesawtron

2/3/2026 at 9:05:49 PM

What is the coffee doing?

by s0rce

2/1/2026 at 2:55:48 PM

I'm puzzled by this. Why hasn't there been, over the last fifty years, a huge amount of research into EM staining techniques and which materials were best under which circumstances? Edison supposedly tried 3000 different materials for light bulb filaments before settling on charred cotton thread. Why hasn't something similar been done in this area?

Or perhaps it _has_ been done and that's why nearly everyone uses uranyl acetate? And perhaps coffee was tried decades ago and found to be generally inferior?

by mjd

2/1/2026 at 3:49:09 PM

Of course it's been done, and there are lots of different stains available: https://www.agarscientific.com/general-consumables/chemicals...

by BigTTYGothGF

2/1/2026 at 3:54:03 PM

Wow you know it’s a fun party when the first result needs to specify it’s _not_ radioactive

Oh I see - Uranyl Acetate is radioactive and this replaces it. Fun!

This seems like a friendly chemical too - “ The chemical properties of Osmium Tetroxide are such that use and handling of the chemical is often considered daunting. Although its volatility and toxicity certainly makes it a dangerous chemical, but when following the proper procedure and taking the necessary precautions, Osmium Tetroxide can be used to its full potential with limited risk to the user.

This is more toxic than glutaraldehyde and has a higher vapour pressure. Particular care must be taken to avoid breathing the vapour or allowing it to affect the eyes. ”

by buildbot

2/1/2026 at 5:39:55 PM

Uranyl acetate for staining is typically depleted and unless you have regulatory issues I don't think the radiation is a big concern, especially when you compare to the very serious toxicity of OsO4 (vapors can react with your eyes and blind you).

by s0rce

2/1/2026 at 7:19:52 PM

Interesting and makes sense! I know nothing but what I read from the stain description haha. OsO4 seems incredibly nasty. So do a few other of the stains!

by buildbot

2/1/2026 at 11:39:04 AM

You just know how they found out about this...

> "I got the idea of using espresso as a staining agent from the circular dried stains in used coffee cups,"

Suuure...

by jacquesm

2/1/2026 at 11:59:58 AM

Quoting more:

> "I got the idea of using espresso as a staining agent from the circular dried stains in used coffee cups," says Claudia Mayrhofer, who is responsible for ultramicrotomy at the institute. During preparation, she cuts tissue samples into wafer-thin slices and fixes them onto sample holders. Staining is the last step before examination under the electron microscope.

I'm curious about the grad student who is the second author on the research paper. Is he the one tasked with the current-SOP staining with (radioactive and poisonous) uranyl acetate? Was it his overworked-and-drowsy "oopsie" which lead to the discovery?

by bell-cot

2/1/2026 at 5:47:25 PM

Amusing, but no (at least I sincerely hope). Food and wet samples are never in the same vicinity as a matter of OSHA (plus just a general desire not to get yourself or others killed). Violating that would typically be a great way to speedrun getting fired.

Radioactive substances go beyond that, generally being handled in their own dedicated area that no one else is permitted to enter for any reason. The level of paranoia is actually fairly impressive (but obviously necessary).

by fc417fc802

2/1/2026 at 2:00:48 PM

You figure they accidentally spilled some coffee and just went with it? That's my guess.

by mikkupikku

2/1/2026 at 5:57:31 PM

One of the references: “Oolong tea extract as a substitute for uranyl acetate in staining of ultrathin sections”

by ravila4

2/1/2026 at 4:10:27 PM

I'm reminded of how blacksmiths use instant coffee to stain damascus steel, at least the ones on YouTube

by Rastonbury

2/1/2026 at 6:50:19 PM

Does that last long? Commercial damascus is typically acid etched which seems like it would last better, but it wears off eventually too.

[edit] oh, I guess coffee is acidic, so maybe it’s not that different. I was thinking of using it as a stain at first

by peacebeard

2/1/2026 at 11:54:25 AM

Calling it now: this is ignobel prize-worthy research. If it doesn’t get a nod I’ll eat my hat.

by fredley

2/1/2026 at 11:47:35 AM

Make sure to leave out the hazelnut syrup.

by amelius

2/1/2026 at 10:02:35 AM

One does not simply ... ordinary espresso.

by hahahahhaah

2/1/2026 at 12:08:38 PM

Next up: "Coffee in Austria recalled due to high concentrations of heavy metals"

by Metacelsus

2/1/2026 at 9:47:36 AM

[dead]

by its_ubuntu

2/1/2026 at 10:05:34 AM

Starbucks doesn't even have good coffee and it's WAY overpriced.

It's an abomination. Trust me!

Black coffee in McDonald's is superior in quality and price worldwide. Especially in UK and Switzerland.

Please explore - Starbucks is baaaad

by iberator

2/1/2026 at 11:18:38 AM

True but on the other hand their coffee beans bags they sell in stores made for the best coffee I have had.

I tried to buy beans from coffee snobs independant stores but all I got was weird and/or acidic coffee

But hey I am a tea person first and foremost, what do I know

by cassepipe

2/1/2026 at 1:28:23 PM

There are definitely speciality shops that sell dark roasts like you might want. One in the UK, Rave, sells the most amazing Italian-style blend with robusta mixed in. It's not fruity at all, just pure dark roasty flavour (yes, I've got an espresso bar lol.)

That darker style gets frowned upon a lot ("bleuch! it's bitter!"), as a lot of people in the space have kinda embraced the more fruit-forward lighter roast stuff (if you roast darker, you tend to obscure them.) I like that too (some stuff is kickass), I just categorize it separately from darker stuff.

I believe some people have started calling it goop, presumably as an anthesis to soup, which is very coarsely ground espresso typically using lighter roasts.

Not sure where you're based (US?), but there will be stuff out there. Try r/coffee or your local forum maybe? Once you find a really good one, you'll probably just stick with it :-)

by tentacleuno

2/1/2026 at 12:41:45 PM

I’m going to hate myself for saying this and sounding like such a coffee snob, but: if coffee tastes bad to you, there’s a decent chance you just haven’t had a good cup of coffee.

I only say this because I used to hate coffee too, only having had Starbucks or crappy supermarket coffee made at home. But then I had a cup of coffee at a very good restaurant and it was so delicious. It was just black coffee, good beans prepared right.

Turns out I just prefer light to medium roasts and found the right brewing times and temps that I like best. Every time I have Starbucks it still tastes awful.

by nkrisc

2/1/2026 at 4:02:33 PM

I was turned on to Chock full o' Nuts years ago, and have never turned back. I will drink any coffee in a pinch, but for great mild coffee I stick to Chock full o' nuts in my french press.

by zafka

2/1/2026 at 12:24:40 PM

There are actually a whole bunch of good medium to dark roasts out there, but third wave coffee is hip and has been for a while.

If you like Starbucks beans, you'd probably like a better dark roast. Try Lavazza. Coffee snobs will look down on it, but they're highly consistent like Starbucks while offering more variety and more flavor. Lavazza Super Crema makes a pretty nice espresso and is cheap relative to high-end coffees.

by terribleperson

2/1/2026 at 1:30:45 PM

Ehh, who cares what the snobs think? Drink what you like! I've been experimenting with coffee for like 2 years, and have found myself really enjoying dark roasted stuff (as well as lighter stuff!)

The truth is, you can get a really fruity single-origin bean but as soon as it goes into a latte, typically you've lost 99% of the origin characteristics. It gets a bit wasteful and expensive. Cafes typically go for house roasts that lean darker, and I can see why: they just work better in milk!

by tentacleuno

2/1/2026 at 12:27:56 PM

Yes, their cappuccino milk is foamy, not creamy. For the price I expect cappuccino art. And they serve it too hot. 3 out of 5 stars at most and subtract one star for the price.

by amelius

2/1/2026 at 10:03:25 AM

No... maybe you misread... they said coffee.

by hahahahhaah

2/2/2026 at 2:35:27 AM

[dead]

by its_ubuntu

2/2/2026 at 3:01:29 AM

I love a rollercoaster comment. Goes up, then down.

by hahahahhaah