Yesterday I posted a question/poll about how much of a change in the dose of coffee do you need to make a difference in the taste of your coffee. The collective answer seems to be that you need at least 0.5g difference in the dose of the coffee to make a difference in taste, all other things being equal. This is in line with my experience, as the times I’ve made a change in dose to tweak the taste of my espresso, I’ve gone in 0.5g jumps, as changing the dose by less than that doesn’t seem to do anything in my hands.
The reason I asked about this is that my workflow in making espresso in the morning includes weighing 18.0g of beans on a super cheap scale I got from Amazon (I know, I know). After grinding, I weigh the ground coffee to make sure that there’s no retention.
What I’ve noticed over time is that the weight of the ground coffee is sometimes the same as the initial beans that I weigh. What’s more common, however, is that the weight of the ground coffee coming out is 0.1-0.3 g more than the weight of the beans I put into the grinder. The ground coffee never weighs less. I kept track of this, and over the course of last week I’m up by 1.5g.
I have only 2 explanations for this.
- Although my scale displays the weight to 0.1g of accuracy, repeatability to 0.1g doesn’t happen. (You get what you pay for.) When I’m grinding my 18.0g of beans, 18.0g of ground coffee is coming out, but the scale gives me 18.2 because of the repeatability issue. This seems to be likely, as when I weigh the dosing cup, take it off the scale, and put it back on, the weight bounces between 109.1-109.3g. I also think that from one morning to the next, the scale is accurate enough, as I consistently get the espresso that I want with the 18.0g of beans I’m weighing out to start.
- My grinder is magically creating coffee each time I use it. This would be a violation of thermodynamics, however. The plus side of this scenario is that I’ve solved global warming. 😆
The reason I asked about how much of a change in dose makes a difference in taste is that I wanted to gauge how much of an issue this really is. Whatever my scale is doing, it seems like it’s within 0.1-0.2g in terms of repeatability. This means that this inaccuracy may be a moot point if it takes a larger change in weight to change the taste of the espresso.
The main thing I use my scale for is to see if I have retention during the grinding process. If the weight of the ground coffee is consistently higher than what I first weighed out with the beans, and I use the bellows on my grinder until I don’t see any more coffee coming out, I’m pretty sure I’m consistent with getting to the zero retention point. The few times I’ve taken apart my grinder for cleaning bears that out, as I’ve never seen big collections of coffee inside the grinder.
My OCD side is telling me that I need to get a new, more accurate and repeatable scale for making my espresso because it has this error of 0.1-0.2g.
My practical side is telling me that because (1) I can consistently make excellent espressos from my wife and myself every day, and (2) it seems that the collective experience is that it takes at least a 0.5g change in the dose of coffee to change the taste of espresso, that the scale is good enough for this purpose.
Am I missing something here? Should I get a new scale anyway?