I currently have an old R2 Refractometer [URL=https://i.imgur.com/71yNCKV.jpg][IMG]https://i.imgur.com/71yNCKV.jpg[/IMG][/URL] [URL=https://i.imgur.com/MnHZKJv.jpg][IMG]https://i.imgur.com/MnHZKJv.jpg[/IMG][/URL] Its very time consuming to use: 1) clean the glass 2) bring unit and glass to room temperature (within a specified range) 3) ditto for the distilled water 4) calibrate the unit, 5) setup the extraction syringe and its filter 6) take the sample 7) express the sample into a mini beaker 8) dilute the sample to a specified ratio 9) bring the diluted sample to a specified temperature, within a narrow range 10) ensure that the R2 glass and the sample are at the same temperature 11) place a drop of the sample on the R3 glass 12) run the test, 13) repeat test multiple times 14) calculate average result 15) enter data into EY calculator 16) note the result That is just too much faff to be bothered. Is there an easier way, perhaps with a different unit?

The VST Lab II & III zero quickly and have better accuracy, precision and temperature compensation, they also produce a reading in a few seconds (compared to the rolling display of, say, the Atago, never used the Reichert, from before my time). Why are you diluting the sample? (Step 8). This seems faffy & a possible margin for error? But all will need zeroing, syringe filtering and 30s or so to let the expressed syringed sample cool, then again to equalise on the lens. It sounds like the main basic procedure is what you have a bugbear with. So the later models are a little bit less faff, but most of the procedure remains. I find it easy enough to measure every filter brew I make (98% of the coffee I drink) without syringe filtering, but I only occasionally do runs of measurements on non-filtered methods due to the cost of syringe filters. Noting & retaining the EY and correlating to your preference score is essential for the refractometer to give you any meaningful info.

Thanks for full reply @"MWJB"#139 . Appreciated! And found this [Refractometry Workflow](https://pocketsciencecoffee.com/2022/12/07/my-current-refractometry-workflow/) And this, from the coffee influencer superego we all know [Ultimate Coffee Refractometer Showdown](https://youtu.be/yF2fIaQS70k?si=1wyorF3xPwI8penX?t=1490su) PS Is the Reichert R2 Mini I have (which I believe was a collaboration between VST and Reichert) sufficient for my purposes? Will I gain much by buying a more recent model, or a Dilfuid R2 or ?

VST have instructions on how to take sample, https://cdn.shopify.com/s/files/1/0092/7622/files/VST_Lab_Coffee_III_USER_GUIDE.pdf?3540336393965960970 I rarely use my Atago because the workflow is slow and it's about half as precise as the VST Lab II (despite additional calibration by the vendor at purchase), which is what I consider the minimum for filter coffee, OK for espresso though. Tim Wendelboe has a video for espresso measurement here: https://www.youtube.com/watch?v=NPp0fpnH_0A For filter, I spoon about 5ml of a stirred brew into a shot glass/espresso cup, let it cool for 30-60s (whilst rinsing the just used brewer), then drop 3-4 drops onto the refractometer, allow another 30-60s to equalise and take 3-5 reads depending on how stable the reading is (half the time no variation, sometimes varies by 0.01%, sometimes by 0.02% at the most). Add to that 30-60 seconds minimum to let the distilled water equalise for zeroing prior to use (maybe while measuring out a coffee dose) and the whole process only adds about a minute to a brew. I use 3ml plastic pipettes for dropping the sample on the refractometer, these are easy to flush with 0TDS water, allow to dry out & reuse, also less prone to delivering 'bubbly' samples. The DiFluid is absurdly cheap for the spec it quotes, but I've not tried it and have too many refractometers that I don't/can't use, already. A more modern VST will be more precise a quicker to zero.

I can definitely recommend the difluid R2, the older model isn't very good but the new one is more than good enough, we have 5 of them (and I have my own one)and they all tested very similar compared to the VST that we use for QC and the atago we had. The R2 has a few quality of life features that make it nicer to use, the app is good as well but thankfully not required to use the refractometer. I like the workflow from pocket science, the temperature stabilises very well so all of the readings are close together. And having distilled water ina dropper makes it nice and fast.

> @"InfamousTuba"#p54382 they all tested very similar compared to the VST that we use for QC Interesting! Would you mind sharing the comparative results done over a sample, which can be 10-15 different coffee. It will also be good to see the standard deviations of the results. DW, if it is too much of a work. 😊

I’m wondering if my original Reichert r2 Mini (which was the result of a collaboration between Reichert and VST; it's effectively the VST I), which is accurate to 0.1 TDS, is sufficiently accurate? By comparison, the Difluid is accurate to 0.03%, as is the VST III. If my current Reichert R2 Mini is sufficiently accurate then I will just continue to use it and not throw $$ at yet another accessory. If it's not, then I would not use it. And think about what my coffee budget priorities are. FYI, with my R2, you do have to dilute the sample for espresso testing, as the unit can’t handle espresso TDS and produces an error code. But it's easy enough to make the mathematical adjustment. Any thoughts on the above @"DavecUK"#1 or @"MWJB"#139 or anyone else?

@"JHCCoffee"#p54406 You won't be able to test accuracy (so reliant on manufacturer's figs), only precision/repatability. The R2 coffee is stated as accurate to +/-0.1%TDS, +/-0.05%TDS typical. The VST Lab II is accurate to +/-0.05%TDS (precision +/-0.02%), Lab III accurate to +/-0.03%TDS, precise to +/-0.01%TDS all figures for coffee, rather than espresso. At filter strength 0.01%TDS equates to about 0.14%EY, or 0.03%TDS to around half a %EY. Precision much outside of +/-0.04%TDS starts to make things tricky over a sample of filter brews.

@"LMSC"#p54403 I can probably do that comparison in the future, might be a while until we have free time at the roastery to do it properly. The R2 had slight variance but they were consistent, so if one unit tested 0.05 TDS higher it was reliably always 0.05 TDS higher

If my math is correct, if I have a 2:1 espresso brew ratio, and a .10 (10%) TDS, the EY is .20 which is 20%. If I have a 2:1 brew ratio and a .101 (10.1%) TDS, the EY is .202 which is 20.2%. So the EY impact of .1% accuracy at a typical espresso brew ratio is only 0.2%, which is meaningless? The only thing is that I have to dilute the espresso sample by say 2:1 or I get an error code. But I can simply adjust the EY formula math for that by multiplying the resultant EY by 2.0 So my Reichert should be good enough. Am I missing something here?

@"JHCCoffee"#p54412 Your math is fine, you can multiply the TDS by the brew ratio (for espresso as it's based on beverage yield, not brew water poured). What you are maybe missing is that you seem to be confusing 'resolution' (the number output by the refractometer display) with 'accuracy' (the reading relative to a known datum, usually dehydration carried out by the manufacturer and fairly moot as far as we are concerned) and precision (the ability of the device to replicate that number when taking multiple readings of the same sample). This is the same for many devices, especially scales for instance, some are accurate to 0.1g, others read to 0.1g resolution but are only accurate to 0.4g. So, if you have an espresso that is 4x the dose weight and reads 5.05%TDS your EY is 20.2%, it could really be +/-0.2%EY if the device is +/- 0.05%TDS. No big deal, as you say. Or, +/-0.4%EY span if the reading is out by 0.10%TDS. Still useful. The higher concentration of 1:4 shots is working in your favour here, but as the concentration of the brews gets weaker for filter coffee, the precision gets worse. 1.40%TDS +/-0.05% at 1:14 (dose:beverage mass) is 18.9% to 20.3% for readings of the same sample. Repeated brews of the same coffee & method may span 2%EY or a tad over, You're going to brew multiple coffees from varyious origins which will double that span (rule of thumb), still around 4-5%EY and the target range is typically 4%EY. Still doable, enough to be of some use. It doesn't necessarily matter if your average is 19%EY or 21%EY, rather than 20%, other factors could have a bearing here. Precision is more useful for checking brew consistency. As you go farther out with the readings to say +/-0.10%TDS you now have a span of 3%EY for the same 1:14 filter sample, by the time you are considering different origins your range of readings is as wide as the likely extractions that are typically possible & much wider than the target region…not much use at all. If you are primarily concerned with espresso (especially if you can read the undiluted samples at around 1:2), this may not be of concern to you, filter generally requires better accuracy & precision.

Easier to Use Refractometer ?

MWJB

LMSC Syringes can be flushed with distilled water, dried & re-used. The filters are single use, no I don’t re-use them. Hasbean are the UK distributors of VST products.

MWJB

LMSC I can’t see the raw data, or sampling method details there, not sure why they tested with sucrose as only the dual scale Atago shows Brix v TDS, the other devices do not display Brix.

Looks a bit confused & sloppy to me.

Why 19 samples on the instant?

Why test 5x R2 but only 1 each of the others?

Not trying to convince you, or anyone else of the usefulness of the R2, A bigger study than my test would be better, but this doesn’t look like it.

LMSC

MWJB I generally tend not to judge articles / research that fall outside my area of expertise.

But, my immediate thoughts were notable variations in the outcome between DIfluid devices, yet still showing them on a positive framework, and VST apparently underperforming against home truth.

The data used in research is generally not published IMO. One can contact the authors, should the data be required. Of course, I am no way affiliated to the author. 😁

Your research and tests are not just invaluable to baristas but also completely transparent and unbiased. So,

Giphy - Well Done Good Job GIF by Pudgy Penguins

:-)

MWJB

LMSC and VST apparently underperforming against home truth.

There is no ‘home truth’ for the sucrose test, again because sucrose is measured in the Brix scale which is not available for most of the devices shown.

Neither is there ‘home truth’ for the instant coffee because they haven’t carried out any filtration & dehydration to back up the dissolved solids assertion. As I stated, early on, I am not aware of any influencers, commentators nor bloggers who are equipped to make determinations on accuracy compared to a datum/home truth. This is exactly why I avoided discussing accuracy (apart from relative averaged readings vs manufacturer’s own claims).

JHCCoffee

Bumping this, for access.

DavecUK

One thing I found important for the Di Fluid R2 is to definitely have the samples at room temperature. A good guide as to whether you have not been successful seems to be where the reading continuously drops as it takes samples. I think it’s cooling down when it does this.

Since I definitely cool down to room temp now, the systems 3 readings seem consistent.

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