Refractometer

[sosman]

Wont help you with brix to SG but if you want to compensate hydrometer readings for temperature then I have an online form here which lets you print out a table for whatever temperature your hydrometer is calibrated for.

I also have a units converter if you ever wanted to know how many litres in a firkin.

 

[Daznz]

10 Brix in promash is 1.040

 

[Ross]

10 Brix in promash is 1.040

Daznz - Any reason for reviving this 2 year old thread :huh: ??

Cheers Ross

 

[Darren]

Doc

Just wondering if you're still using the same data that you posted back in Feb 2003. I've been playing around with the calculations for refractometers and there appears to be considerable difference in the results of Brix to SG conversion depending on the equation you use. The simple equation is just to multiply the Brix by 4, so 10Brix would be a SG of 1.040. Using your calculations it would be 1.041. Using an alternative formula reported in BYO magazine in November 2003, you would get a SG of 1.039. The formula that you used for the table is the same one used by the guy who makes PrimeTabs, which are a bit like Coopers Carbonation drops. The supposed Guru on the matter is a guy called Louis Bonham who came up with the formulas for ProMash.

The other significant difference is that ProMash uses a wort calibration factor set at the default value of 1.04. This is because Brix refractometers are meant to measure the percentage of sugar in a pure sucrose solution, but wort is not simply sugar and water, so you need to make a small correction for the non-sugar components. Using the PrimeTabs equation plus the calibration factor would equate to a Brix reading of 10 to 1.039 and using the the formula from the Nov 2003 BYO magazine would give a SG of 1.037.

So depending on the formula you use and if you calibrate for wort you could interpret a Brix reading of 10 as high as 1.041 or low as 1.037. I'm still not clear on what the best equation to use is. I suppose using ProMash takes away the need to try and work this out for yourself. If anyone has ProMash what does it measure 10 Brix as in SG?

Cheers
MAH

MAH,
Now you can't tell me you don't have time to chill your wort.
I understand now. You have been quibbling with 4 SG points.

Those measured differences would fall outside the accuracy of homebrew measuring device.

cheers

Darren

 

[cj in j]

For anyone who's interested, here are a set of on-line calculators that make converting a refractometer Brix reading to specific gravity, and it even works for post-fermentation readings.
Thomas's Refractometer Calculators

I should mention -- you can save the page to your hard disk and access it any time, even without an Internet connection. You can also delete the Google ads on top in a web page editor.

Oh, I just noticed that I can add an attachment to this post, so here it is: View attachment __Refractometer_Calculations.html

Quick note about the attachment -- when I just did a test download, it opened in MS Word, which is definitely not what you want. Open the file in an Internet browser and it should work fine (although I can only test it in Netscape).

 

[sinkas]

Does the accuracy of a refrac reading depend on liquid film thickness?
I recently tried to make a big (1.150) barleywine, and was taking reading through the last alf of the boil, they seemd to be all ove rthe bloody place, 19 to 26 and inbetween. Near the end it seems to stabilizes somwhat between 23 and 26, I was alittle miffed when it came out at only 23 when cooled....
My refrac is a Mashmaster unit

 

[Screwtop]

Temp!

Take a small sample using the dropper. Swirl around in the bowl of the dropper and leave it for 5 min or so, then take your reading, from experience.

 

[oldbugman]

I've noticed readigs to to vary quite a bit during the boil after hops have been added.. could it be the hop oils?

 

[sinkas]

The unit says it temp compensating.

 

[mika]

So does mine, but once the wort cools down the readings a lot different. I take the dropper and sit it for ~5mins before taking a reading, but then I'm not fly sparging and got no need for an instantaneous reading.

 

[Ross]

The unit says it temp compensating.

It is, but only within a certain range & is affected by how much you drip/pour over the lense. I find if you draw a small sample it cools very quickly. I drop a few drips from the pipette onto a metal teaspoon which in effect drops the temp instantly - This can then be dropped on the lense for a consistant result. I always take 2 readings though, just to be sure.

cheers Ross

 

[mickoz]

I found a very nice spreadsheet that does all the math necessary to use your refractometer all the way from mash to bottling provided you provide an OG.

http://morebeer.com/public/beer/refractbeer.xls

There's a tutorial here as well http://morebeer.com/learn_vids/vids_refract

Mick

 

[Hogan]

I found a very nice spreadsheet that does all the math necessary to use your refractometer all the way from mash to bottling provided you provide an OG.

http://morebeer.com/public/beer/refractbeer.xls

There's a tutorial here as well http://morebeer.com/learn_vids/vids_refract

Mick

I'm finding the issue of Brix = Gravity readings very confusing as of late. I have always relied on Docs chart but these latter charts, refrac tools and BrewSmith calculations can differ quite considerably. Who is right? Which chart, tool should I follow??

Cheers, Hoges.

 

[BrissyBrew]

I'm finding the issue of Brix = Gravity readings very confusing as of late. I have always relied on Docs chart but these latter charts, refrac tools and BrewSmith calculations can differ quite considerably. Who is right? Which chart, tool should I follow??

Cheers, Hoges.

I looked at bringing out refractometer with brix and SG for wort (pre-fermentation) but I have consulted a few text books, brewing formula, a few pieces of brewing software, a few online calculators, formula supplied in Magazines (brewing industry, and also others eg juice) at the end of the day I found no consensus on the formula to be used for pre-fermentation. The big issue is some formula are based on a clear liquid (think more japanise rice beer) and others are tweeked to turned out a lager. Technically you are suppose to calibrate the refractomer to the wort (if you are doing the same brew over and over again such as in a commerical brewery).

I am interested in people opinions regarding acceptance of an approximate SG (prefermentation scale) probably best for getting prewort gravity/run off from the sparge readings.

 

[SpillsMostOfIt]

I am interested in people opinions regarding acceptance of an approximate SG (prefermentation scale) probably best for getting prewort gravity/run off from the sparge readings.

It's a real *******, IMO. I think in SG as does the world (of homebrewers) apparently. But I love my refractometer.

My ideal would be a slide rule type device that I could zwoosh-zip to apply whatever formula I wanted then get my SG. A wheel, perhaps?

Nowadays, I use a table I made or switch back and forth in Beersmith... Very elegant.

 

[Ross]

I just use my refractomer for rough brew day calculations, where I want to check my preboil gravity etc. Used in this way, a simple 4 x brix calculation is more than adequate & makes the unit worth it's weight in gold. When I require more accurate data, & during fermentation I use my hydrometer.

cheers Ross

 

[Cortez The Killer]

It's interesting to look at this analysis here

http://www.basicbrewing.com/radio/xls/BrixPlatoSG.xls

And a spreadsheet I setup here

http://www.aussiehomebrewer.com/forum/inde...st&p=237324

I'm not 100% on which formula is most accurate

Though I reckon that it'd be worth tabulating a range of user comparisons between refractometers and hydrometers at a range of gravities - to determine which formula gives the most accurate real world results

Perhaps a AHB feature to record this or a wiki on topic would be good

Cheers

 

[PJO]

I just use my refractomer for rough brew day calculations, where I want to check my preboil gravity etc. Used in this way, a simple 4 x brix calculation is more than adequate & makes the unit worth it's weight in gold. When I require more accurate data, & during fermentation I use my hydrometer.

cheers Ross

I used to use mine the same way (until I dropped it, must get another, looks like your up for another order soon Ross ).

I did'nt think that it was possible to get an accurate reading with a hot solution regardless of ATC.
The problem I can see is in cooling down a small drop, while it may only take a minute, you are bound to lose some water through evaporation, so I've never used it as an accurate reading just a guide.

Though I'm not sure how big the loss is through evaporation or whether it is even big enough to worry about.
How do people cool down the solution before putting on the refractometer?
Any chemical engineers out there to do the calculations? I guess it would strongly depend on humidity.

Cheers,
Petr

 

[Sammus]

They annoy me. I have to take about 6 readings, and then I take the two that agree (if I'm lucky there will be two) from that lot as my reading... which is normally way off what my hydrometer says anyway. On top of that the little steel pin holding the lens cover was loose and i finally lost mine last night.. looks like ill have to dodge it up with a nail or piece of wire or something.

 

[Kai]

I just use my refractomer for rough brew day calculations, where I want to check my preboil gravity etc. Used in this way, a simple 4 x brix calculation is more than adequate & makes the unit worth it's weight in gold. When I require more accurate data, & during fermentation I use my hydrometer.

cheers Ross

Exactly what I do.