Don't use a Refractometer for FG readings. Your beers didn't stall at 1.024.

[Kalvaroo]

If those OG's were taken using the SG scale on your refrac, we can't trust them. Sorry, the OG scale on these things is garbage. We can sight across the picture and pretend that we know what the OG is in Brix, but that's not really accurate to the point we can make judgments about 1-2 point differences.

Look at your pictures. The one on your phone shows 1.120 is 28.2 Brix. The one in your refrac shows 1.120 is about 31.0 Brix.

I agree. I'm going to shop around for a new refrac.

EDIT: After reading up on my refrac. I ran across some more info on the MoreBeer website, and a lot of websites sell this "Dual Scale Refrac w/ATC" and say it's adjusted correctly to give accurate results.

More Beer said this;

Getting Geeky about why the Specific Gravity Scale on our unit is accurate
Some dual scale refractometers feature a linear scale that multiplies brix by 4 to get Specific Gravity. This is okay at lower gravities up to around 1.040 but the higher your starting gravity goes, the less accurate the conversion is. For example, take a Brix reading of 10, multiply by 4, and you get a SG reading of 1.040 - the accurate SG reading is 1.041. Take a Brix reading of 20, multiply by 4, and you get 1.080 - the accurate conversion is 1.084. We worked with our Refractometer manufacturer to create a unit with a non linear conversion and thus this model can be accurately used for Specific Gravity readings.

NorthernBrewer says this:

A Brix Refractometer that includes a specific gravity scale. You won't have to do conversions between Brix and gravity when measuring musts or wort. Measuring final gravity accurately will still take some calculations.

So basically this is what I got so far... the refrac is accurate before fermentations, then use the conversion tools available to get accurate results throughout fermentation. Not entirely sure which scale is accurate before fermentation though... they hint that the SG scale is accurate before fermentation.

My question now is... how do i properly use a dual scale refrac (the popular one everyone sells)? Before and during fermentation...

As in, which scale to use when, and when to do the conversions, and which conversion?

 

[iaefebs]

If I remember right Morebeer adjusted the dual scales a few years ago. The picture of the scale on their website photo contradicts their "getting geeky" statement since it still shows the same scale as pictured in post #57
Maybe they never updated a stock photo, but it only adds to the confusion.

 

[TrickyDick]

Well,

I first read this thread to figure out why my readings seemed "off" having just recently bought and started using a refractometer. I feel like a dummy, that I thought my beer stalled, and now I know the reason why: I wasn't accounting for the fermentation!

The rest of the thread seems a bit beyond what I hoped to learn, but I guess as with all things, the devil is in the details.

I will say this however. I have a bad nearsightedness. Like 6 diopters of correction. In order to read it, I need to take off my glasses, and then is hard to concentrate on not spilling the sample. Its also hard to keep air bubbles out at times. When I do get a read, the line is blurry, and the smaller lines are so hard to see, that I am wondering how accurate I can get with this instrument. I will try a filter and the other tricks suggested.

In spite of these shortcomings, it seems many are able to get "good enough" readings, which is probably fine enough for me.

Thank for the enlightening thread!

TD

 

[stpug]

Well,

I first read this thread to figure out why my readings seemed "off" having just recently bought and started using a refractometer. I feel like a dummy, that I thought my beer stalled, and now I know the reason why: I wasn't accounting for the fermentation!

The rest of the thread seems a bit beyond what I hoped to learn, but I guess as with all things, the devil is in the details.

I will say this however. I have a bad nearsightedness. Like 6 diopters of correction. In order to read it, I need to take off my glasses, and then is hard to concentrate on not spilling the sample. Its also hard to keep air bubbles out at times. When I do get a read, the line is blurry, and the smaller lines are so hard to see, that I am wondering how accurate I can get with this instrument. I will try a filter and the other tricks suggested.

In spite of these shortcomings, it seems many are able to get "good enough" readings, which is probably fine enough for me.

Thank for the enlightening thread!

TD

Yeah, now drop a transparent glass tube in a light transparent liquid and tell me you can find the meniscus with more certainty than a blurry refractometer line

 

[thadius856]

Refractomerers have diopter adjustments built in. Try screwing back the eyepiece.

 

[ajdelange]

My question now is... how do i properly use a dual scale refrac (the popular one everyone sells)? Before and during fermentation...

Back in #51 I posted paired values for specific gravity and Plato/Brix. Look at your refractometer. If the Brix numbers match the SG numbers in #51 then at least the SG scale is properly calibrated to the Brix scale.

The next step would be to obtain or make a 10 Brix solution. Do this by weighing out 10 grams of sucrose (table sugar) and adding 90 grams of water (add water until the total mass is 100 grams). Check that your instrument reads 10 Brix at the temperature for which it is calibrated. Given that they can't properly translate between Bx and SG I don't see why we should be confident that they can properly translate between RI and Bx.

Given that you get 10 Bx and that correponds to 1.040 SG then you can use either scale. If it is one like those that have been illustrated here where the SG scale is incorrect you will have to rely on the Bx scale and convert Bx to SG. Given the inherent inaccuracies in using refractometry the inverse Lincoln equation should be plenty accurate:

SG = (668 - sqrt(668*668 - 820*(463+Bx))/410

or SG = 1 + Bx/(258.6 -0.8796*Bx)

All this is before fermentation where you will usually get an answer within 1 or at worst 2°P. After fermentation starts all bets are off. You will have to use one of the formulas that float around the net and hope it comes close to matching your beer.

 

[TrickyDick]

Yeah, now drop a transparent glass tube in a light transparent liquid and tell me you can find the meniscus with more certainty than a blurry refractometer line

I agree with you there! Reading the "meniscus" in a hydrometer flask or tube, the fluid sticks to the stem of the hydrometer! So where are you supposed to "read" the fluid level?!? Plus, it is often not entirely level, or has spun away so you can't read the numbers. I think it does that to trick us!

I guess we need to work with the tools we have however, and I guess this is the best aside from fancy land uber expensive ab equipment.

TD

 

[TrickyDick]

Refractomerers have diopter adjustments built in. Try screwing back the eyepiece.

My eyesight is beyond the ability of these eyepieces to correct. Most such eyepieces have a diopter adjustment of +/- 2 usually. My correction is about a 6. at close range, I can manage with the eyepiece however, since I am nearsighted. Wearing glasses or contacts however, is pointless to attempt to use the refracto.

TD

 

[ajdelange]

...the fluid sticks to the stem of the hydrometer! So where are you supposed to "read" the fluid level?!?

Wherever the manufacturer tells you to. A good hydrometer's calibration includes the surface tension effects of beer/wort not water. The instruction sheet should either direct you to read at the bottom of or top of the meniscus.

I guess we need to work with the tools we have however, and I guess this is the best aside from fancy land uber expensive ab equipment.

A good set of brewing hydrometers can be read to about 0.05 °P. That's plenty accurate enough for anything a home or craft brewer is doing.

 

[TrickyDick]

Wherever the manufacturer tells you to. A good hydrometer's calibration includes the surface tension effects of beer/wort not water. The instruction sheet should either direct you to read at the bottom of or top of the meniscus.



A good set of brewing hydrometers can be read to about 0.05 °P. That's plenty accurate enough for anything a home or craft brewer is doing.

I didn't get any instructions with my hydrometers. I'll have to contact the manufacturer. I think its BrewFerm or something similar. and BTW, is it true that hydrometers are inaccurate at temps 100F and over?

TD

 

[ajdelange]

They are inaccurate at any temperature except the temperature for which they were designed IOW they only read the specific gravity correctly at that one temperature. Correction tables and formulas can be found in dozens of places on the net, in books etc.