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We were in the market for a digital refractometer - as we find regular floating hydrometers cumbersome and wasteful in terms of the amount of fluid required to take a sample.
Initially we were looking at a handheld 'telescope' style refractometer, but our research suggested that these were wildly inaccurate and unreliable - to the point that correction charts need to be calculated and maintained in order to get any sort of accuracy when using them. Check out this video from Flora Brewing on YouTube to see what is involved in doing this. Needless to say, this is not something we were willing to do - we're looking for ways to make our brewing days and processes easier and more straightforward, not more complex and convoluted so we started looking at options for digital refractometers.
As you'd expect, digital refractometers are a significant price jump from the previously mentioned handheld refractometers. After some research though we discovered that some digital refractometers can be found on AliExpress at a price point somewhere between the handheld ones and the digital ones available from other online stores.
The one we found looks just like this one from Fruugo which at the time of writing this article, was on sale for $289. We were able to purchase one from the "Soonda Goodfaith Store" on AliExpress for around AU$118 including delivery. If you're in the market for one, make sure you get one that reads Brix of Specific Gravity as these are the scales generally used for brewing.
No doubt if we post a link directly to the item on the AliExpress website, the link will eventually break, so here's a screenshot of the actual advertisement for the one we purchased.
We know buying from AliExpress can be a little hit and miss - but certainly in some cases bargains can be had for seemingly identical products at a fraction of the cost of those sold in regular retail or other online stores. We wanted to take the gamble so took a punt on buying one from AliExpress.
As expected when buying from AliExpress, shipping was from overseas but was surprisingly prompt. It arrived in a nice plastic hardcase, however the plastic clips to secure the case are just folded plastic so will no doubt snap off in due course after being open and shut many times.
Inside the hard case is the actual refractometer, a plastic pipette for drawing samples, a screw driver for removing the battery cover, as well as a microfibre cloth for cleaning the lens.The refractometer requires a single AAA battery which isn't included.
We performed an initial accuracy test by testing a sample directly from our latest All Inn Brewing Co fresh wort kit - which has been stamped with a gravity of 1.060
Straight out of the box without running any calibration, we had a reading of 1.068 - 8 points higher than the specific gravity of our wort at 1.060
Our next reading of the wort was now a whopping 1.076 - 16 points higher than the known value. Obviously the calibration threw everything way out, so we ran a calibration again using distilled/spring water instead.
After running a calibration again using distilled/spring water, we were able to get some more consistent readings of around 1.062 and 1.063, which was still 2-3 gravity points higher than expected
We did find it interesting that the volume of sample (ie. number of drops) placed onto the lens of the refractometer seemed to affect the readings. Using 2 drops seemed to give the best results, with using more than 2 drops causing a reading significantly higher.
Admittedly we've only tested the accuracy of this unit against a single sample with a gravity of 1.060. We plan on doing some further testing of samples with differing gravities and will compare the results against a regular floating hydrometer. It's possible that lower gravity samples may be more accurate.
We'll update this article again once some more testing has been done, but at this point the results seem reasonable, but not as accurate as we'd like. It's perhaps a fair compromise between a floating hydrometer and the 'top of the line' digital refractometers.
Check out the results of our further testing and comparison between this digital refractometer and our floating hydrometer.
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