Refractometer

[Nebraskan]

I have been looking on line for something from a standards body that is more definitive than secondary sources, but am not having much luck (most standards bodies want to get paid for their publications.)

Brew on

Here is the thing. I asked at work another winemaker about Brix. 100 ml of water weighs 100 grams. So you and I are both right. 10 grams in 100 mls is 10% ref: http://mathcentral.uregina.ca/QQ/database/QQ.09.06/s/shian1.html

 

[hawkbox]

That is the beautiful thing about metric.

 

[doug293cz]

Here is the thing. I asked at work another winemaker about Brix. 100 ml of water weighs 100 grams. So you and I are both right. 10 grams in 100 mls is 10% ref: http://mathcentral.uregina.ca/QQ/database/QQ.09.06/s/shian1.html

Not quite. 10 grams of sugar + 100 ml of water equals 110 grams of solution. 10 g / 110 g = 0.091 or 9.1 wt% = 9.1°Bx. However, if you add water to 10 grams of sucrose to make 100 ml of solution, you will use significantly less than 100 ml of water, so the error will be much small than 0.9°Bx. I'll figure out what the exact error is, and post back here.

And, to be really pedantic, 100 ml of water only weighs 100 grams at 4°C. At 20°C (68°F) 100 ml of water weighs only 99.82 grams. Not a big error, but if you're calibrating, you want to be as precise as possible.

Brew on

 

[portguy]

Not quite. 10 grams of sugar + 100 ml of water equals 110 grams of solution. 10 g / 110 g = 0.091 or 9.1 wt% = 9.1°Bx. However, if you add water to 10 grams of sucrose to make 100 ml of solution, you will use significantly less than 100 ml of water, so the error will be much small than 0.9°Bx. I'll figure out what the exact error is, and post back here.

And, to be really pedantic, 100 ml of water only weighs 100 grams at 4°C. At 20°C (68°F) 100 ml of water weighs only 99.82 grams. Not a big error, but if you're calibrating, you want to be as precise as possible.

Brew on

Even when using wheight/volume there's an obvious catch: if adding 100 ml of water to 10 grams of sugar, the end solution will be 115,9 ml , as sugar has a 1,59 g/cm³ density.

It's good info when making priming solution in a target volume that is easily divided.

 

[doug293cz]

Even when using wheight/volume there's an obvious catch: if adding 100 ml of water to 10 grams of sugar, the end solution will be 115,9 ml , as sugar as a 1,59 g/cm³ density.

If you assume ideal solution theory (solution volume = component 1 volume + component 2 volume), then 10 grams of sucrose at 1.59 g/ml is 10 g / 1.59 g/ml = 6.29 ml. So, with 100 ml of water the total volume would be 106.29 ml. I don't believe sucrose in water follows ideal solution theory, but at around 10°Bx the error is quite small.

Brew on

 

[portguy]

If you assume ideal solution theory (solution volume = component 1 volume + component 2 volume), then 10 grams of sucrose at 1.59 g/ml is 10 g / 1.59 g/ml = 6.29 ml. So, with 100 ml of water the total volume would be 106.29 ml. I don't believe sucrose in water follows ideal solution theory, but at around 10°Bx the error is quite small.

Brew on

Yes. Of course you are right. That is how i calculate my target volume exactly when priming with a syringe.

 

[Nebraskan]

At the winery today I took in my refractometer and zeroed it with deionized water (from our special resin filter) I ran brix on 3 grape samples with a 24-16 Brix hydrometer and then tried the same juice on the refractometer. It was about 2 deg Brix low. What I did was use one of the 3 samples that was 23.2 Brix on the refractometer and using the small screwdriver, adjusted the refractometer to read 23.2. I then tested the other 2 juice samples that were close to this Brix reading and now it was spot on. I am not sure how accurate it would be when reading down around 13 deg Brix.

BTW my Dad lived in Renton WA when he was alive and retired from Boeing. He managed to get me a job out there at Plant II back in 1977. Beautiful country when you get outside of the city *like in the Cascades*.. kind of OT but

 

[doug293cz]

At the winery today I took in my refractometer and zeroed it with deionized water (from our special resin filter) I ran brix on 3 grape samples with a 24-16 Brix hydrometer and then tried the same juice on the refractometer. It was about 2 deg Brix low. What I did was use one of the 3 samples that was 23.2 Brix on the refractometer and using the small screwdriver, adjusted the refractometer to read 23.2. I then tested the other 2 juice samples that were close to this Brix reading and now it was spot on. I am not sure how accurate it would be when reading down around 13 deg Brix.

BTW my Dad lived in Renton WA when he was alive and retired from Boeing. He managed to get me a job out there at Plant II back in 1977. Beautiful country when you get outside of the city *like in the Cascades*.. kind of OT but

Not surprising that a juice sample might not read the same as a sucrose sample, just like a wort sample doesn't read the the same as sucrose. A hydrometer always reads SG, no matter what is in solution.

Back to the OT. My dad also worked for Boeing for a time (on the 747), but I never did. I actually left the Puget Sound region for work in late 1977, but moved back in 2013 to retire. It's still beautiful, but you have to go a little farther to get away from the population density.

Brew on

 

[Nebraskan]

This link might be of use in this thread. It talks about wort correction, and making up a 20 Brix/ 1.083 S.G. solution using DME and water. https://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/

Just for clarification on the above post, I was not adding 10 grams to an already 100 ml of water (which would be 110g ) but it was added as "Part Of" the 100 ml. Sugar dissolves and will take up space, so to be more accurate, 10 grams was added to "some" water in a 100ml volumetric flask, allowed to dissolve, and then the volume was brought up to the line representing 100 mls in the volumetric flask. I think it comes closer that way to an actual 10% solution, but not an exact ... but close.