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View Full Version : Refractometer vs Hydrometer



McJeff
01-07-2015, 10:00 AM
Just started using my 26 dollar refractometer i bought off amazon. Im totally in love, why would anyone ever use a hydrometer when you can spend just a little bit more for the refractometer?

edblanford
01-07-2015, 10:43 AM
I would like to use my refractometer (actually I have ended up with two, as one came with a used batch of misc. brewing stuff I bought a while back), but unsure of the proceedures when alcohol is present. Maybe one of the experts could provide a tutorial? Hint hint, Medsen Fey, who seems to use both regularly.

EJM3
01-07-2015, 01:21 PM
http://www.northernbrewer.com/refractometer-calculator/

http://onebeer.net/refractometer.shtml

McJeff
01-07-2015, 04:18 PM
You are just making my case that much easier against hydrometers ;)

GntlKnigt1
01-07-2015, 06:48 PM
Doing the conversion is an extra step when using refractometer. I generally use mine in must preparation, or in situations where hydrometer doesn't have room to float. Each has their place

Medsen Fey
01-07-2015, 06:56 PM
I like to use a hydrometer at the end of fermentation, and during aging to insure stability. In many cases there is enough variability from drop to drop to give you uncertainty about stability with a refractometer. However, for tracking an active fermentation, I love using a refractometer.

Sent from my THINGAMAJIG with WHATCHAMACALLIT

Sleepy
01-16-2015, 11:26 AM
I have done a bit of looking around and reading on the use of refractometers and it seems to be a consensus with most serious brewers that you have to make an adjustment for the off-clear nature of the liquid being tested. A refractometer is calibrated to measure the sugar dissolved in a clear solution (RO or distilled H2O), so having a semi-clear/light amber must as the test sample requires some additional corrections to the equation. Has anyone that uses a refractometer found a way to deal with this?

Earendil
10-09-2017, 05:38 PM
I know this is an 'old' thread but thought I'd add this information in case it is useful to subsequent viewers.

I recently got a refractometer and have been very pleased with it. It saves me the time, mead and cleanup involved in using a wine thief with a hydrometer.

As others have noted, however, as the alcohol in the must increases, the refractometer readings become progressively more inaccurate. As EJM3 pointed out, there are websites like northernbrewer that have calculators which will calculate the current gravity, given the original Brix and the current Brix.

I found it more expedient to build that calculation into my own mead log form. It took a bit of searching to find the formula, so I thought I'd share it with others who may want to use it in their own mead logs or programs.

The formula calculates the Current Specific Gravity as:

=1.001843 - (0.002318474*OB) - (0.000007775*OB*OB) - (0.000000034*OB*OB*OB) + (0.00574*CB) + (0.00003344*CB*CB) + (0.000000086*CB*CB*CB)

Where OB = Original Brix and CB = Current Brix

You can paste this formula into a spreadsheet or use any programming language to incorporate this conversion formula into your applications. A spreadsheet example would work like this:

Name cells A1, B1 and C1 with labels "Original Brix", "Current Brix" and "Current Gravity" respectively
Format cells A2 and B2 as numbers with 1 or 2 decimal places. Format cell C2 as a number with 3 decimal places.
Paste the above formula into cell C2, substituting 'A2' for 'OB' everywhere it occurs and 'B2' for 'CB' everywhere it occurs.

Now, entering the original gravity (in Brix) in cell B1 and the current gravity (in Brix) in B2 will result in the current gravity (in S.G.) being displayed in cell C2.
If your mead logging form is a spreadsheet, you can use this formula to automatically convert your refractometer readings to S.G. everywhere they are useful to you.

As Sleepy pointed out, the sharpness of the refractometer's dividing line decreases as the mead gets murkier but it is still within a few points and accurate enough (in my view) for most purposes, such as determining when you're close to the sugar breaks, how fast the fermentation is progressing and so on. What I did was take readings side-by-side, using both hydrometer and refractometer to get a feel of where, in the 'twilight zone', I should be taking my readings. Having done that, I find they are consistently within 2 to 4 points of 'reality'.

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Eärendil
Miruvor maker and Eternal NewBee
Mithlond Meadery, Grey Havens, Eriador