Science Discovers What We All Missed: More Than An Anti-Static Hack 

I’m not sure why the links aren’t showing for some people. Here they are: The Google Survey: forms.gle/aggEtudDCnqUVRZr7 The Paper (Direct Link): bit.ly/wetbeans Supplemental Paper: bit.ly/coffeestatic

New bad coffee trend, drink only positively charged coffee grounds, throw away the identical negative charged grounds.

It’s always a pleasure to watch these videos. And even more of a pleasure to watch James slowly transition from barista to a coffee research scientist with his own laboratory

It’s fascinating that the spritzing makes a MEASURABLE difference to the extraction of the espresso. I could totally see “well in theory this should have a marginal benefit but in reality it’ll probably never mean anything,” but it’s amazing that they were able to actually measure a meaningful, quantitative change.

My suggestion for the slowing flow rate would be that the coating of water on all the coffee particles drastically increases the capillary action of the coffee bed, which usually I would think is fairly hydrophobic if dry. The oils in the coffee also probably don't help with that. If you try to water dry soil versus slightly damp soil, you see the effect of a thin water coating makes orders of magnitude of difference. So a stronger capillary force from the already present water allows the coffee to be drawn into the packed bed more evenly and reduces the chances of channels forming, leading to higher leaching rates and slower flow rates. This is not contrary to what the prof said. It might be a combination of both.

I love the citizen science your channel is promoting, and that you're encouraging mixed and unclear results to be shared. There is a signal here, we just can't see it yet. Keep sharing, keep signal boosting, and keep experimenting!

A month ago I thought, I was a pedantic home coffee guy. After discovering this channel, I'm now weighing my coffee to 0.01g and micro spraying with distilled water and I can firmly say that the rabbit hole is significantly deeper that I ever expected...BUT I can also say that you firmly improved the consistency of my espresso shot.

I am SUPER excited that you got a particle size analyzer, and from a legit analytical science company like Anton Paar. That is an incredible leap towards quantifying the impact of different grinders, burrs, grind RPM, etc, which so far has been limited to assumptions. Wow! That instrument is a significant investment too and I'm thrilled you got to a place where your fame and fortune, so to speak, can be put towards advanced coffee science to benefit all weird coffee people everywhere! I'm assuming we'll be seeing a lot of grinder studies now using that instrument. Can't wait =)

I was not ready for this man's voice... Like a warm cup of coffee

As a scientist and coffee drinker, I really enjoyed this video.

“I have a half dozen grinders…I don’t have enough” this killed me haha

The reason you're not seeing particle size differences in your particle sized analyser is probably because it breaks up the electroclumps during the measuring process. No idea the details of how the machine works, but it would be far from surprising if it was violent enough to the micron sized particles to break up the electroclumps into their constituent grains.

I used this spritzing water method a few weeks back before this paper was published. My grinder is the new Fellow Opus. It was the first time I did it with the Opus because I never thought of doing it since the grinder has anti static tech. And I was so surprised that when wet, it took vastly much longer to reach 36g than when it’s dry. Now that this paper has been published, I’m going to try it again!

You reminded me - for pour over filter coffee, I discovered that if I bloom the coffee with room temperature water (73F ish), then brew as usual with the rest of the water off boil, the taste is amazing. It retains a lot more VOC content and the aromatics are way better. I don’t usually care for pour overs much, but this changed the game for me. You can experiment with bloom temp, but I prefer room temp.

I am absolutely certain that if 1% of humanity increased the level of interest and passion in what they did, regardless of what that may be, to even a fraction of what you do with and for coffee the world would be a much better place. Thank you James for encouraging people, through coffee, to do more, do better and question what they do.

Man, this video is surreal. I don't think I ever had a chance to meet him specifically, but I was just at a small conference with Chris Hendon a few months ago and met several of his students and heard a bit about his coffee research. I don't think I've ever seen someone I've encountered so closely in such a popular piece of media as this. I suspected that he or his work about coffee (though he also studies wine and other compounds more relevant to industrial chemistry) would show up here eventually though. Super exciting stuff!

This is fascinating! There's a nugget here about grinding frozen coffee. I've been freezing beans for freshness since I use coffee pretty slowly. An unintended result is that when I take out a dose of 18 grams of beans to grind, pretty quickly they get covered in a nice even layer of condensation because they are so cold. It's like getting a mist and mix for no effort. Hard to control the amount (which is a function of time and the relative humidity in the room), but interesting nonetheless. I've also had no issues with grinding frozen beans in my Breville Barista Express or my Fellow Ode gen 1, and not surprisingly I've had much less issue with static compared to grinding room temperature beans in the same grinders.

I've been struggling with static on my coffee grinder for so, so long. This video is my game changer. THAN YOU VERY MUCH.

James, I would love if you could get a multimeter and measure the resistance of the various materials the griders are constructed from, particularly where the machines directly contact the ground coffee at the end of the grind. My theory is that more conductive surfaces like metals will better dissipate the charges than plastic insulators. I think this likely accounts for that initial difference you noticed between different grinders -- the Eureka Mignon Oro has a metal spout and cup.

Interesting. I've been using this much water already, because a single spritz was never enough to get rid of the static. My grinder after 3 years of doing so is perfectly clean inside, as I just did a maintenance run of it last week.

The mention of frozen coffee was interesting to me. I wonder if dosing out of the freezer (Or freezing a premeasured dose) and allowing it to defrost a bit before grinding would allow for enough water to condensate on the beans to where an additional spritz of water wouldn't be necessary to observe these benifits? I wonder if maybe that effect played some roll in your findings on grinding frozen coffee beans?

Decided to try this again after giving up on misting beans ages ago. Somehow forgot that I’d since repurposed the atomizer for adding orange blossom water to homemade orgeat. While I can’t endorse deliberately using orange blossom water in your coffee grinder, it certainly made for an interesting espresso and a real Proustian moment while I played “what the hell is that weird perfume flavor?”

Even though I'm not "that into" coffee and usually just guess each time I make it, I absolutely love your videos. It's not just the information, but the candor, the dedication without obsession, and the curiosity. I wish there were clones of you making RU-vid videos on different topics - it'd be a better world.

I just wanted to drop some extra information that wasn't in the survey since I found this very interesting: I used a Fellow Opus and had an 18.4g dose (pre-ground) for both dry and wet beans. I used 0.4g of water on the beans to try to match the recommended dosing, but I couldn't be exceptionally precise, and just used the scale to measure a general amount that I dropped in and mixed. I noticed that my grind time increased from 17.19 seconds dry to 21.75 seconds wet - however the dry grounds lost .1g to static that I was able to keep with the wet grounds, so ultimately the dry grounds brewed 18.3g of coffee to 40g out and the wet grounds brewed 18.4g of coffee to 40g out. There was noticeably a difference in the texture and distribution in the grounds as well - the dry grounds tended to clump together when moved around and the wet grounds were completely loose and would not clump or stick to any receptacles. It was noticeably easier to distribute the wet grounds and dose it into my portafilter. To a point, it seemed to not even need a distribution tool as there was virtually no clumping to begin with. My dry shot measured 20 seconds to yield 40g and wet took 31 seconds. Neither shot produced any noticeable difference apart from the length of time, there was no impact on crema or any strange occurrences during the shot. I checked both pucks, and because I use a puck screen I wouldn't expect there to be any channeling, and sure enough neither puck showed any signs of channeling. Both were completely in tact and looked to be about the same volume, though I didn't think to weigh them and see if they had any noticeable difference in that way. Finally on flavor: both had a very similar flavor, however I would say there was (and it could be confirmation bias) just a bare hint of extra flavor in the wet grounds. Tasting both side by side it was a very minor difference, and it could even just be a shot to shot variation from any number of factors, though I attempted to control everything as much as possible. Overall I personally find that the experiment really just gave me a good reason to use the RDT method because of the distribution and ease in actually prepping the shot rather than any additional flavor benefit. The 11 second difference in shot time was fascinating, but the flavor wasn't significantly changed enough to warrant the technique on that behalf with my grinder and brewer. Thank you, as always James, for giving something to think about and having us along for the journey!

I think one aspect has been overlooked in the experiments you described: time scales of the wetting process might have a relevant role in the process of both triboelectrification and fractoelectrification. What was the elapsed time between wetting the beans and grinding them? It takes time for water to diffuse evenly into the beans. A suficiently long period should be allowed for the water to diffuse evenly into the beans in a way that the beans would have a uniform moisture content and consequently promote uniform stress transfer throughout the beans during grinding. If the elspsed time between wetting of the beans and their respective grinding was different for different experiments, the resulting effects related to tribo and fractoelectrification would certainly be different.

If you close your eyes you can experience what it’s like to have Jon Hamm describe coffee physics to you

Long-time lurker, first time joining in, and this finally got me to actually incorporate the spray. No difference for me in brew time (Compak K6), but less retention so I'll keep spraying. Data's also delivered to Google Forms, can't wait to see what's next!

As a fellow scientist, I find this fascinating! It makes me happy to know there’s scientists out there studying coffee

This is fascinating. I have the Eureka mignon zero and I felt like I’ve noticed a small difference in the extraction time when spraying and not spraying. Going to be doing some experimenting now to really see if it does or not!

Works well for me. I use the 1ZPRESSO hand grinder and now I have almost no grounds adhering to the burrs at the outlet, grinds don't cling to the bottom receptacle either. Visibly less clumping. Grinds flow smoothly out of receptacle into the Porta filter unlike before when I had to tap firmly to remove them.

Love this video. It's great to see coffee educators like you and Lance covering this kind of material. We are nerds, and this is very indulgent! Also, the one electroclump quick text had me cracking up.

I just started doing 3-4 sprays about 2 months ago, it made a huge difference in the blockage I was getting in my grinder, I almost bought a new grinder because it was so frustrating having to shake bang and remove top to brush out grinds. Thanks for the video

About the results from the particle size analyzer not changing with spritzed beans: such analyzers results depend on how you fluidize (suspend/homogenize) the sample before loading it into the machine. That will be different than how those grounds interact with water flowing over them when they're already in a lump in the coffeemaker (ie, in the coffee maker the *effective* particle size will be finer, since without the spritzes it forms clumps). Those clumps can be broken up in the process of preparing the sample for analysis. To test this, you could freeze a lump of wet grounds post-brewing, take a cross-section of it, then look at it under an optical microscope.

I wonder if the condensation that occurs when keeping coffee beans in the freezer and bringing them out for grinding leads to more of the same as spraying with water

"My most intellectual turtleneck" - this is why I follow this particular coffee channel :)

From Lance to James, wet beans are the new craze!

I just got into making espresso at home, and your channel has been a fantastic find during my recent journey. I'm making some stuff at home that is better than any coffee place I've ever been.

I use a Chestnut C3 Pro hand grinder, usually for aeropress coffee. 22 g beans to 400 g water. I tried out the water squirts and it definitely looked like the grind was more even and very little clung to the grinder which was very nice. 4 squirts of water onto the beans before grinding. I’m sold!

Good morning, James Longtime listener, first time responder. I have a Rancilio Silvia and a Baratza Sette 30 using 18g. After 4 spritzes of water I found fluffier grounds in the portafilter after grinding. At 27.3 seconds I stopped the brew with 34g (the point I stop brewing without water on the beans), however the weight out was 38g with the spritzed beans. I found the flavor of the espresso richer with the spritzed beans. I had used the single spritz a couple years ago and didn't find enough change to warrant the additional step. Thanks, JS

"I'm left with more questions, than answers" -Welcome to scientific reasearch, it is fascinating but unsatisfying at times ^^

Do a video where you ask beginners/intermediate coffee people to submit videos of them making coffee. You could get great info about the most common mistakes, giving you better info when making guides.

For removing variables for filter coffee, you could use one of those cafe automatic pour-over machines. You could even do different numbers of water spritzes on like four different doses and start the brews all at the same time.

Super interesting - so I did the experiment (added to survey). I have the Niche Zero (64MM conical burrs) and an Isomac Zaffiro (e65) machine - using a WAFO basket. My normal dose is 17g in / 34-36g out at 19 seconds (because of WAFO basket) at ~ 202F for my dark roast espresso blend from Anderson's Coffee in Austin, TX. What I've found so far is that with ~ 4 spritzes of water, it is immediately obvious that that espresso powder is fluffier in the grind cup. Moreover, it adds about 6 seconds to the extraction time. Flavor profile is as good if not better than my normal routine.

I just finished watching the Lance Hedrick video on the paper and this one, back to back. Both utterly fascinating. I'm 47 years old and until three years ago I absolutely hated coffee, detested it. So much so I called it Satan's Sputum. However, my only access and experience of coffee was commodity instant. Now I watch an hour and a half of coffee science videos from 7am on a Sunday morning 😂 Brilliant piece as always James, and I love that immediately you encourage your viewers to participate in the science. I started with an Aeropress after watching your Ultimate Aeropress technique video. Graduated to a Clever Dripper, again after watching your video about it. And I'm hoping to buy my first espresso machine in the next few weeks. The obsession continues

THIS is exactly the kind of episode I live from James.

Who has time for a spray bottle when you can just buy a $4500 grinder like Lance?

I don't follow all the advice in these videos because I don't make coffee in the same way, but I still love these because it just makes me excited to drink coffee and enjoy that part of my day more so thank you.

I've been trying this for a few weeks now. Only got a spinning blade for a grinder and i make coffee in a moka pot but I've found once ground the coffee grounds aren't as clumpy and the actual coffee has so much more flavour compared to usual. Thanks yet again for another tip enlightening my coffee experience

Great to see more science being publicly available.

This is why I keep coming back. The balance between the goofy fun stuff and the citizen science videos and scientific paper analysis. It's all about the balance. And the slurps. 😂

Two new coffee makers I'd love to see you review and hear your take on. The Orb One, which works like a moka pot but has a couple of significant innovations... and the Kuku maker, which separates water temperature from water pressure, allowing for a wide range of variation and experimentation.

i own a grinder from ceado. it comes with titanium covered burrs specificly against water damage or rust. they also recommend 2-3 spritzes with the spray bottle that comes with the grinder, which was more than what I was used to, but worked pretty well...

great video. Making the parallel with Soil compression when we build roads, it is important to add moisture to achieve the right compression and soil sensity. Maybe coffee reacts the same way. Hence adding moisture helps to get the puck density higher. I did not test this hypothesis, however if this is correct, spraying after grinding and just before tampering would lead to a longer shot. Food for thoughts

The Weird Coffee Professor 2: The ElectroKlumps

One major issue is the way the water is applied to the beans: whereas usually the water is spritzed on the coffee, in the paper they used a pipette to apply water and shook the beans in a sealed container.

In hindsight, it is quite reasonable that spraying coffee with water would make the distribution more even because of less electrostatic clumping. Excited to see a follow-up once more is known about what's happening (or at least the possible results of the different variables at play when grinding.)

The turtleneck, the hand on chin, the nods, exceptional work James!

Grind it, then retest moisture content, see if the moisture is lost during the grinding process. Honestly, I just got to where you said you are having varied results with each machine, that tells me yes, the moisture is like grind lube, and you want to dissipate the moisture before the final dispersement into the cup.

This is fascinating to learn about! There is one point I think you may be a bit confused on. You talked about not thinking the effect of adding water to the beans not being statistically significant when grinding with the Eureka. What you described sounds more like effect size. Statistical significance refers to the probability that the observed effect was due to random chance rather than due to the intervention. You can have an effect that is statistically significant but very small.

I do not see the link for the google form?

For my experience I find that during the winter months, when the heat is on, the house is very dry, and I have in inordinate amount of static electricity in my grounds. So far, I have used a big stainless steel canning funnel to get the grinds into the hopper of the drip brewer and that seems to dissipate the static charge. I then upend my grinder and give it a tap to get as much of the grinds as I can to fall out of the grinder into the funnel. I will give the mist a shot and see if this takes care of the annoying static charge. Great video James thumbs.

I use a 1z presso J manually grinder as my daily and I’m intrigued if this will make a difference, particularly as it’s not a machine grinder. I’ll be sure to fill out the form! Excellent video, James - fascinating as always.

honest curiosity.. why don't we just ground the grinder?

Looking forward to experimenting with this - I have not been sprizing of late and am currently chasing grind size as I'm getting what I think is under-extraction and a sour soapy espresso from my DF64. I'm also wondering how environmental factors play into this as well. My kitchen is not a lab and is not climate controlled so humidity and air temp are going to be factors in the variability of the results - which might also explain why I keep getting different results using the same grind, beans, distribution techniques and variability in the extraction time on my gaggia.

Around 6:00: I've been using the DF64 for the past 2 years. This grinder has a massive amount of status, basically requiring me to use RDT every single time i grind my beans for espresso (2 times per day, rarely 3 times), with 2 sprays for each grind because 1 spray only negate the static partially, not nearly enough to eliminate it altogether. Using RDT with this grinder, i discovered that the flow rate actually slows down as the aforementioned paper indicates. Therefore, i concluded that the 2 sprays of water results in the ground being more sticky, causing them to be reground. I got it partially right! The water attracts the fines and causing the fines to be regrounded!

If someone asked me "what does coffee sound like" I think its Chris's voice, that sort of deep rich sound, that's the perfect voice for coffee!

I think electroclump sounds awesome, and the name is correct imo, even though after it is formed it’s not electrified anymore, the reason that it is formed in the first place is that the particles that end up creating it are electrified in the first place.

I'd love to see a video on applying this to filter coffee grinding. Also, since I've been drinking decaf, stored in Fellow vacuum canisters in the freezer, I'd love to throw in the additional wildcard of frozen beans and adding water or not.

Hi ! I have a cheap wilfa conic shaped burrs grinder and I use it for filtered coffee. I always spray my coffee beans. About 4 sprays for 30g. I feel like it change the flow rate but IMO it increases it. Also the grind result is way more uniform with the sprays. I have way less fines. These two techniques WDT + RDT are the most game changer I witnessed so far in my coffee life.

00:00 🎬 *Introduction to the Coffee Static Hack* - Explaining the history and usage of the Ross Droplet Technique (RDT) in reducing static electricity when grinding coffee. - Introducing the scientific paper revealing new discoveries about the effects of adding water before grinding coffee beans. - Discussing the three parts to be covered: why water is needed, the impact of adding water before grinding, and the unexpected effects on coffee brewing. 01:27 🔬 *Understanding Coffee Grinding & Static Generation* - Exploring the mechanisms of static electricity generation during coffee grinding: triboelectrification and fractoelectrification. - Highlighting the variability in how coffee generates charge and the challenges in predicting its charge. - Describing experiments visualizing the charged particles' movement using positively and negatively charged plates. 04:18 💧 *Role of Water in Mitigating Static Accumulation* - Detailing how water acts as a dielectric medium, mitigating charging during grinding and dissipating heat. - Discussing water's multiple roles in changing surface chemistry, cooling beans, and acting as an interfacial barrier. - Addressing the scientific significance behind understanding the impact of water addition on espresso brewing. 06:15 ⚙ *Effect of Water on Espresso Brewing & Electroclump Theory* - Investigating the surprising impact of water quantity on espresso brewing, altering flow rates and extraction levels. - Proposing the concept of "electroclumps" formed during grinding and their potential influence on flow uniformity and extraction. - Exploring the theory behind water's role in preventing electroclump formation and its impact on brewing quality. 08:39 ☔ *Risks and Considerations with Adding Water to Grinders* - Addressing concerns and potential risks associated with adding water to grinders. - Discussing the moisture accumulation in grinders and addressing potential risks, albeit minimal, associated with water addition. - Encouraging cautious experimentation while highlighting the need for further research and collective testing. 11:05 🧪 *Replicating Study Findings & Grinders' Varied Responses* - Explaining the attempt to replicate the study's findings across different grinder models and the unexpected results. - Speculating on differences in charging mechanisms between grinders and the impact on the effectiveness of water addition. - Encouraging viewer participation in an experiment to understand the impact of water addition across various grinder models. 15:23 📊 *Community Experimentation & Unanswered Questions* - Proposing a collective experiment to measure the impact of water addition on different grinder models. - Acknowledging unresolved questions related to the impact on filter coffee and the potential taste differences. - Emphasizing the need for further exploration, shared insights, and a collaborative approach to unraveling these discoveries. 18:45 🗣 *Call for Engagement & Reflection* - Expressing gratitude to the researcher and team for sharing insights and advocating for accessible coffee science. - Urging audience participation, inviting thoughts on the paper's impact on coffee brewing, and encouraging experimentation and sharing of results. - Soliciting feedback and opinions on the effectiveness of the current approach and potential alternative solutions in dealing with static in coffee grinding.

Its literally the same reason that you get more static shocks in the winter when the air is super dry as opposed to basically zero shocks in the summer when the air is humid. Identical concepts.

i read this in the washi post, suggested by google, so discovered it in my "own" way! immedeatly, in my next shot, I dripped 3-4 drops of water on the beans, the ground them. Noticed longer shot time, and noticable increase in total flavour. What an amazing find!

I have found that holding an ordinary baking brush under the tap, shake off most of the water, and then stir the beans with it before grinding provides a much better distribution of moisture than a micro sprayer (and less sticky mess).

My partner always makes the coffee in the cone filter completely saturated with water before letting it drip. The reason is because it's easy to see with a cone filter that sometimes the water will find a bit of a "river" to follow, and leave most of the surrounding grounds completely dry. So it's not just an espresso thing. 🧐☕

I’m wondering what difference a hand grinder makes? I use a comandante for espresso and known that if I spray the beans before grinding that the grounds don’t stick to the bottom of the burrs or the inside of the glass jar nearly as much. It makes less mess, but I wasn’t sure if the whole set up would change things (e.g. slower, less uniform grinding times; maybe contact with the metal chamber and a person’s hand?). I’d try the experiment, but I also use a Flair, and my consistency is… adequate for the occasional drink at best :D

Honestly, the wet to dry ratio inside of the grinder would still lean it to being dry while frinding thanks to the powder, and it becomes more homogeneous aswell. Partily blooming the powder and keeping it at a lower temperature before brewing.

I have a Kinu hand grinder. I never sprayed the beans before at all. Started spraying four times like in this video. My shot time was way faster went from 28 seconds down to 20 seconds. But I had a lot less clumps before I started doing my preparation, so I think it’s more valuable of preparation.

I wonder if the charging isn't partially the reason why steel burrs are preferred to ceramic ones. Steel is a conductor so it would help in dissipating the electric charge while ceramic is usually an insulator which can't conduct the charge away so the overall charge in the coffee would be higher. Because usually as a cutting material ceramic is usually better - longer lasting, harder etc.

I watched this video a couple of weeks ago, and tried praying the beans with a couple of spritzes of water before grinding. It made all the difference in the world in keeping the fine particles from flying all over the kitchen, and this was all I was looking to get out of it. Clean-up time has been reduced enormously. I don't see any difference in the brew, as the channeling James discussed has never been a problem for me. I'm not using a fine grind, as I brew with a Hario Switch, so this aspect of the process isn't really a player for me. While I'm nit seeing any changes in the brew, I like not having to sweep up a lot of fine coffee particles every time I brew.

I've recently stopped doing the RDT. It was my suspicion that adding water was causing too many clumps and causing my puck prep to suffer. So now I just overdose by .2 ish to compensate for retention, and my puck prep and pulls have been more consistent. Maybe I was using too much water, but I'm still happier after removing it from my workflow.

I did the experiment over a couple of weeks now. All in all, I think I liked the result a tiny bit more with that method. BUT I never did a side by side comparison. Just tried changing my routine to add more sprays, and I definitely don't see a huge difference. Now. I have to say, though, that it made grinding significantly harder with one particular bag of beans that were a bit more oily. To be clear, they are high quality beans from a local roaster, not burnt costco beans where the oil has no choice but to bead on them; they just have a bit more oil than usual. But with those beans, adding more water made them stick to my hopper, the burrs, the chute, etc. I had to deep clean my grinder after just a few days, and I basically need to grind a dozen beans or so on a really coarse setting if I want to clear the grinder, and that never happened before.

Hi James, very interesting video. I really enjoyed it! I’m food technologist. Maybe the fact that you didn’t find any difference between Df64 dry milled and wet milled is because some analyzers are not able to measure aggregates. Some of them apply a big flow in the chamber for the measurement and can disintegrate the aggregates. Check with Anton Paar if that’s the case. Hope it helps.

Surely the roast profile of the beans has a large part to play in this. With dark roasts being more soluble and less dense (heat up quicker in the grinder) I would think the water would have a greater effect when grinding darker roasts.

Hi 👋 From my experience with particle size analyzers (did a PhD with technical ceramics that involved a lot of particle analysis), one should analyze particles with a visual image as well with the distribution the analyzer gives you. Simply put a bit of that same sample in a slide and see it on a SEM. There are nowadays super convenient table-top electron microscopes that will work just fine for this. This will help to understand further if the distribution consists of weirdly shaped particles or regular, or if they are clumps of small particles sticking together (possibly electroclumps) that are fooling your distribution. I’ll go have a look at that paper now 🙂

The effect on flow time may depend on whether the grounds have time for charge relaxation before the shot is pulled

This just popped up…after only this morning I accidentally wet my beans. Then ground them. Then had a nice cup. Who knew I was grinding in a recognised way when I just didn’t want to waste my beans or wait for them to dry out! Great coincidence. Thanks James.

Tried some water on the beans before grinding. Definitely less to no static. I use an AeroPress, plastic tube, so static is very obvious. But my Baratza Encore was not happy. The next morning just dragging the grinder out across the counter caused little chunks of grounds to fall out. An initial cleaning on/off showed lots of chunks to fall into the discharge container. They had obviously struck while wet and fell off after drying overnight.

I would try an alternative experiment of pre-moistening the grounds. My hypothesis is that spritzing the beans is increasing the moisture content of the grounds which is changing the water absorption / repellence during the brewing process. Materials often become hydrophobic when dry.

My Graef CM 800 made no distinction between wet or dry beans, I sent in the form. Thanks so much for all the videos.

I believe the reason that the Eureka grinder doesn't benefit from RDT is because its anti-static metal piece is at the beginning of the chute so they are more effective than the ionizer at the end of the chute like DF64gen2.

I took a minor in material physics in college, so getting into the rabbit hole that is coffee brewing (started from watching this channel) was really interesting to say the less 😂 I started with a $5 off-brand moka pot and less than $8 v60 set (still uses them), grind my beans with a $10 grinder, now I've added an aeropress to my collection. Won't be buying an espresso machine for a long time still (because of reasons), yet it's all still so fascinating experimenting how all the variables that goes in the extraction process can change the yield performance (sometimes) so dramatically. Feels like I'm in a laboratory again. You can bet I giggled seeing a siphon brewer for the first time.

So I have an Ode 2 grinder and it still has a lot of static. I only make pour-over coffee so the granularity of the grind is "medium". I have to clear it of previously ground coffee that's been statically clinging to the grinder every morning before I can grind my fresh coffee. I think it will be pretty easy to measure the amount of left-over grounds with and without spritzes of water.

I think you should have also asked what machine is used to brew the coffee, because pre-infusion may have a cross-correlation with the sporting effect. In that case, may as well also include filtered coffee in the same survey (with and without pre-wetting).

I do not know the exact way your particle size analyzer works, but if it works anything like the experiments I did in the early 90's, it works by analyzing diffraction patterns of light that is send through a solution of the particle mix you want to measure. In your case that would be a solution of the ground coffee into a compatible large amount of water compared to the size of your sample, while that solution is also well mixed. That would mean any clumps that would have formed in the grinder could easily come apart (they are after all a collection of particles) in other words in that abundance of water the clumps would break apart, and the measurement would not show bigger particles. These clumps would not necessarily break apart during the brewing process because of a few factors. The ground coffee is packed fairly tightly at the start and the entire mass is put under considerable pressure during the brewing of espresso. This probably keeps the particles and clumps pressed together and prevents the clumps from falling apart. Also during the brewing, there is no abundance of water as all the water is pressed through the grinds and passes past the particles without giving them the room to fall apart. I am not very good at using all the right terms (I am not a native English speaker and haven't worked in a lab for about 30 years) but if my impression of how your analyzer works is correct, I am fairly sure this is close to the correct explanation of your measurements.

From a phycicist (master) point of view ask some more questions in the survey: Air temperature and humidity, material of grinding burrs and cup. Every contact with metal will discharge the particle. It may recharge by friction with other nonconducting particles. Wet air is much more able to discharge particles. You know this from electrostatic charging of clothes and hair which is a much stronger phenomenon during winter with low (absolut) humidity than during summer. Also there is this simple question to measure conductivity of sprayed vs non-sprayed coffee. Electrostatic charging is a phenomenon only isolators or very bad conductors show. If there is only a small amount of conductivity all charges in the electroclumps will neutralize instantaneously. Coffee contains lots of soluble ions. A bit of water may transform it from a (dry) isolator to a (humid) ionic conductor.

At last, i understand, why the coffee of our local roaster produces so much static electricity, when grinded with the wooden handgrinder of my grandma. I'm looking forward to experiment with adding water. Thanx for sharing and a happy new year!

Probably a good idea for a qualitative section in the form. --- The only key thing I noticed was that grinding took 5 seconds longer than usual ---- Coffee -- Peet's Big bang medium roast (Frozen beans) ---- No spritz In 18.6g @6 grind setting, took 20 sec to grind Out 53.5g shot Time: 26 sec from first drop ---- 5 spritz 18.6g@6, 24sec to grind Slower flow, darker in beginning, creamier in end Out 56.1g shot Time: 26 sec

I had a small grinder, and abused it. I used it to grind coffee, slightly dampened. I used it to make nut butter! It never complained.

causation/correlation question - how certain is it that the added water is affecting the coffee in terms of the static charge, and not simply presenting moisture to begin the process of re-moistening the now ground beans before brewing? sort of a pre-bloom stage that enables the grounds to become a better puck in the portafilter? maybe it's affecting the static and that sounds nice, but maybe it's just added moisture?

I grind many different varieties of coffee bean in my Niche Zero and over the course of 2 years can honestly say static has never been a problem either in the grinder, cup or portafilter. I just don't see it anywhere in the process. The short clip in the above video of grinds going everywhere is crazy, if people are really experiencing this then suggest considering swapping to a Niche or similar. Tapping the Niche cup a few times before upending in the portafilter helps the process, I don't use a tamper either, just a rotary distributer (using a tamp has no effect at all on extraction times or yield), and gave up using a needle distributer some time age (I don't believe weakly bonded clumps of grinds survive the rotary distributor process so can't see the point, and the rotary distributor does a better job of ensuring consistent depth of puck - far more important than breaking down boulders imo)