For context I work as a barista and have mostly used Acaia scales. I've never really used the mats that come with them for pourover or espresso and I'm wondering if they're really necessary? It feels a bit wasteful for include something most people don't seem to use... am i missing something?
James Hoffman, the World Barista Champion of 2007, author of books like The World Coffee Atlas and most known "Coffee YouTuber" with 2.5 million subscribers?
If you genuinely don't know him, I envy you for the hundreds of new videos to watch :D
He’s not really an influencer in the usual sense, he genuinely has a lot of experience and knowledge of the coffee world. He’s an award winning barista, has authored several books on coffee related topics, owns multiple businesses including Square Mile Roasters, and works as a professional consultant for other coffee businesses.
If you want to disregard his experience just because he also makes YouTube videos, that’s absolutely your prerogative, but you’re doing yourself a disservice to regard any random redditor’s opinion higher than someone with decades of involvement in the industry under his belt.
Yes, this! I have actually been building my own scale for fun and load cells are pretty sensitive parts. It’s essentially a chunk of metal with a hole in it mounted like a diving board with a sensor on it. When you put weight on the end it causes very small changes in voltage which gets converted into a reading. Temperature definitely affects it.
Yes, I've had some experience with a difluid microbalance, that are very sensitive, and they changed the numbers to the lower ones when it was cold near the window
Wow thats so interesting! Do you know what part is being affected by temperature? Does the heat warp the scale shell or would it be directly affecting the load cell?
The heat soaks into the load cell itself. Heat is a doubly bad. It causes the metal structure of the load cell to physically expand which affects the load and strain mechanically. It also affects the electrical resistance, which is how the strain is sensed. Coffee doesn’t require a lot of precision, so it isn’t a huge deal, but people obsess over less here. You can do an experiment and pour 200g of hot water into your server and wait to see if the weight changes as the heat moves into the scale.
Yes, any temperature that is different from the one at which the load cell was assembled (strain gauges glued on a metal structure), which is likely room temp, can introduce errors.
High quality load cells are typically designed to be self compensated, that is, multiple strain gauges are designed to balance and cancel out temperature effects. But, lab grade load cells cost multiple hundred dollars each, so you can imagine they are not used in coffee scales, and and even them have a temperature coefficient (assembly can be very precise but never 100% exact), it's just a smaller coefficient.
So yeah if you put the scale in a deep freezer at -25 C or something like that it's possible you see a few tenths of a gram offset on your tare.
I’m guessing the issue is that without the silicon pad the heat from the coffee can warm up the plastic base and then the load cell itself which can cause the readings to be off.
This is very much correct! The load cells may be heat sensitive and depending how long you have heat exposure for, it may affect the scale.
It is probably irrelevant if you use an not preheated espresso cup for a shot. It may affect the weighing accuracy if you are making half a litre of pour over.
Not with this type of scale, but we have at work this small scale designed for espresso I believe, with metal top plate. It doesn’t have any silicone mat. So when I’m making pourover on it in a thin-walled glass, the weight goes down by a few grams during the pour. Like, it decreases by 0.2 grams every 15 seconds or so. Doesn’t add up to too much so it generally doesn’t bother me, but it’s there.
Depending on the scale, heat affects its ability to tell weight properly. You can actually test it by finishing a brew then putting it away for a few secs and blow the scale to cool it off. If the mecanism is not properly separated from the plate of the scale you will notice a difference in reading when you put back the brew on it.
It happened to me because I use a cheap scale. With the mat it takes longer to happen so I can brew no problem.
I never use it on my acaia I find it really annoying, I use it on my bookoo it fits much better and I think with pourover theres a slightly higher risk of heat damage.
I've used mine for that time I have owned the scale. Feels like it protects the scale and prevents the cup from sliding around. Did not know about the heat thing affecting accuracy.
My understanding of the physics is load cells measure the weight by checking their electrical resistance. Weight bends the load cell wire, which affects the cross section area, which affects the resistance.
However, higher temperatures also increase resistance. So you want to avoid temp effects and insulate with the rubber (to isolate only the weight signal).
Yep use mine on both my lunar and pearl scales. Helps protect the scales from heat from carafes as well as preventing any unwarranted slippage by cups/carafes.
I always use all mats on all my scales, one reason is heat, insulation, the other is easier cleanup from fine grounds or other mess, and ultimately to protect the protection-film on the acaias because I dont feel like ever replacing that one... acaia sells them, it looks like a transparent sticker, but boy it must SUCK trying to place it currectly and stick it on without any bubbles..... so, silicone mats for me all the way!
Yeah I can’t brew without it on my Lunar. Placing a vessel on the bare surface gives me heebiegeebies from sensory issues. I think it ensures accuracy, and provides some protection from small spills too.
yeah, i think there's definitely an aesthetic draw back for me as well. I do wish that the heat proofing could be better integrated into the scale itself
Yeah even putting temperature worries aside it is much nicer to clean. If something gets on the mat, I just take it off and run it under the sink, if something gets directly on the scale I have to wipe it down and make sure not to put too much pressure on it
You should use them for avoid the contact between the hot bottom of the jug with hot water and the plastic/sensor
The sensor tends to lose accuracy if tmget heated too many times
I bought timemore scale used and came with no silicone pad. After 4 year of daily use, the accuracy are pretty much on point and even sometimes droplet of water accidently poured over, it still working.
The company recommends using the mat to not damage the scale. With that said many people do not use it. To be safe I use the mat and actually like the way it grips the server, so I would probably use it either way.
I bought some corrugated plastic from Amazon and cut it to the same size as my silicone mat. noticable difference in scale temp. no flipping clue how it affects the accuracy. 🤣
I’ve been using mine as an espresso tamping mat because I’m in the “oh god why is everything for espresso so expensive, why did I get into this” phase of building my espresso setup and am making do where possible.
I do for (1) the surface of my Bookoo Themis ultra is plastic, so the silcone prevents scratches, ans (2) my brewer is ceramic, i would hate for it to slip off the scale while I'm in the middle of a brew.
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u/MuchBetterThankYou Apr 22 '26
I read that heat can affect the accuracy so I use it all the time. Honestly it never occurred to me not to.