[HN Gopher] Coffee as a staining agent substitute in electron mi...
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Coffee as a staining agent substitute in electron microscopy
Author : PaulHoule
Score : 47 points
Date : 2026-01-29 18:04 UTC (3 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| its_ubuntu wrote:
| Finally, something Starbucks is good for!
|
| ZING!
| hahahahhaah wrote:
| No... maybe you misread... they said coffee.
| iberator wrote:
| 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
| cassepipe wrote:
| 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
| terribleperson wrote:
| 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.
| tentacleuno wrote:
| 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!
| nkrisc wrote:
| 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.
| zafka wrote:
| 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.
| tentacleuno wrote:
| 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
| :-)
| amelius wrote:
| 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.
| hahahahhaah wrote:
| One does not simply ... ordinary espresso.
| jacquesm wrote:
| 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...
| bell-cot wrote:
| 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?
| fc417fc802 wrote:
| 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).
| jacquesm wrote:
| I hope the staining agent is at least visually very
| different from Espresso.
| bell-cot wrote:
| https://en.wikipedia.org/wiki/Uranyl_acetate
|
| - so easily distinguished from espresso. OTOH...
|
| https://www.google.com/search?q=far+side+comic+culture+of
| +am...
| mikkupikku wrote:
| You figure they accidentally spilled some coffee and just went
| with it? That's my guess.
| amelius wrote:
| Make sure to leave out the hazelnut syrup.
| fredley wrote:
| Calling it now: this is ignobel prize-worthy research. If it
| doesn't get a nod I'll eat my hat.
| Metacelsus wrote:
| Next up: "Coffee in Austria recalled due to high concentrations
| of heavy metals"
| mjd wrote:
| 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?
| BigTTYGothGF wrote:
| Of course it's been done, and there are lots of different
| stains available: https://www.agarscientific.com/general-
| consumables/chemicals...
| buildbot wrote:
| 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. "
| s0rce wrote:
| 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).
| buildbot wrote:
| 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!
| Rastonbury wrote:
| I'm reminded of how blacksmiths use instant coffee to stain
| damascus steel, at least the ones on YouTube
| peacebeard wrote:
| 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
| s0rce wrote:
| 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.
| ravila4 wrote:
| One of the references: "Oolong tea extract as a substitute for
| uranyl acetate in staining of ultrathin sections"
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