Does this refractometer scale look off to you?

[brewguyver]

So I was taking a mid-ferment reading to see how things were progressing, and pulled up a calculator with correction factor. It wants to know brix, so I checked my meter. It has 1.065 at about 16.8 brix. So I type that in, and a little pop up says that’s about 1.069.

Weird.

So according to the calculator, 16.2 is the right number.

Is my scale off, or is it just me reading things wrong?

 

[DBhomebrew]

First, if it's not ATC (automatic temperature control) you need to do your reading with the tool at the correct temp. Yours looks to be 20°C.

Second, have you calibrated the tool using RO or distilled water? Even tap will get you close enough.

Third, if fermentation is in progress you need to use a calculator that uses both your OG and current perceived gravity in Brix. Part II here...

https://www.brewersfriend.com/refractometer-calculator/
Fourth, you can typically ignore the SG scale of most $10-20 tools. You need the calculator and correction factor to account for the bigger sugar and dextrins molecules that comprise beer wort other than sucrose.

 

[InspectorJon]

Fourth, you can typically ignore the SG scale of most $10-20 tools. You need the calculator and correction factor to account for the bigger sugar and dextrins molecules that comprise beer wort other than sucrose.

I don’t understand this. If the SG scale is no good, then why is it there? What makes you say to ignore it?

 

[DBhomebrew]

I don’t understand this. If the SG scale is no good, then why is it there? What makes you say to ignore it?

The refractometers we're buying are built for sucrose solutions. Our worts have other gravity affecting molecules such as maltose, maltotriose, and dextrins. These larger molecules refract light differently than sucrose. By reading and recording the SG scale, a brewer ignores that difference. By reading the Brix scale and running the observed Brix value through a refractometer calculator which uses a wort correction factor (WCF), the brewer receives a SG value which more accurately reflects (pun intended) the wort's true gravity.

In my home brewery's logs, Brix values are raw observed data. SG values have been crunched by a calculator to incorporate WCF and, once fermentation starts, to account for the skewed refraction of ethanol.

NB, these practices are derived from reading brewers way smarter and scientifically accomplished than me.

 

[InspectorJon]

Thank you for taking the time to write all that. I just ordered a refractometer the other day. Now I have some more research to do.

 

[brewguyver]

The refractometers we're buying are built for sucrose solutions. Our worts have other gravity affecting molecules such as maltose, maltotriose, and dextrins. These larger molecules refract light differently than sucrose. By reading and recording the SG scale, a brewer ignores that difference. By reading the Brix scale and running the observed Brix value through a refractometer calculator which uses a wort correction factor (WCF), the brewer receives a SG value which more accurately reflects (pun intended) the wort's true gravity.

In my home brewery's logs, Brix values are raw observed data. SG values have been crunched by a calculator to incorporate WCF and, once fermentation starts, to account for the skewed refraction of ethanol.

NB, these practices are derived from reading brewers way smarter and scientifically accomplished than me.

Thanks DB - that answer is very appreciated, and it explains why the Brix and SG values don't necessarily foot. When I was using a calculator, a lot of the values were in Brix, and had an option to switch to SG. That explains why the switching back and forth from calculator on the brix side to the SG side gives me a weird result.

This also reminds me that I need to calibrate with a hydrometer so I can get my WCF.

 

[DBhomebrew]

This also reminds me that I need to calibrate with a hydrometer so I can get my WCF.

Technically, no. The WCF is specific to the wort, not the refractometer. That said, some forum members report their refractometers needing WCFs way off from the typical 1.03-.04

 

[brewguyver]

Technically, no. The WCF is specific to the wort, not the refractometer. That said, some forum members report their refractometers needing WCFs way off from the typical 1.03-.04

Thank you - I definitely read that wrong when I'd researched a few weeks ago. I took the information to mean refractometers had an average WCF, not "brewers have an average style, that might lend itself to an average WCF. You saved me a lot of testing for the wrong purpose.