Refractometer

[SJW]

The way I see it is, when I get a refractometer I will set it to 0 with water and just check all readings with the hydrometer and use the chart that appears to match. I suspect it's just one of thoses things that is just unknown at this stage and we will just have to make the best of what we got. No one is saying to thow away the hydrometer, just use the refrac the best we can.

I decided to trust the hydrometer and took the pilsner out for a Diacetyl rest and hope it drops to 1.017 over 48hour and then I'll rack it.
Bloody oath I love my hydrometer.

:icon_offtopic: I just raised the temp on my Pilsner at 1.020 or so and after 2 days at 18-20 deg C its at 1.014 so I got it crash chilling at 0 deg C for the next 24-48 hrs then I will keg with some Gelatine. BTW I bought some Isinglass and maybe I used it wrong but it does not come close to being half as good as Gelatine for clearing beers.

Steve

 

[goatherder]

Might be able to help you out matti.

The formula from BYO:

SG = 1.000019 + [0.003865613(Brix)+ 0.00001296425(Brix) + 0.00000005701128(Brix)]

is suffering from a nasty typo. Have a look closely at it and it doesn't make sense - why expand the same 1st order variable (brix) into three separate parts?

My best guess is that the equation should have been a cubic, probably based on a regression fit of some experimental data. As such, the equation I've been using for some time is:

SG = 1.000019 + [0.003865613(Brix)+ 0.00001296425(Brix)^2 + 0.00000005701128(Brix)^3]

It plots pretty close to SG = 1.(brix times 4) and really really close to SG = 0.999 + Brix/233 between 0 and 30 brix.

Another tip I've found is to avoid using Beersmith for your conversions. It makes you calibrate the refract to create a fudge factor for all your measurements. The problem is that the fudge factor changes from beer to beer and is probably very dependent on your measurement accuracy. Ignore this altogether, either use the "times by four" method or knock up a spreadsheet with the above formula in it. I've found the above formula agrees with my hydro to within a point or two.

BTW, my refract is supposedly temperature compensating but I often get 0.2 brix difference between a hot sample and a cold sample. Not a big deal, just something to be aware of if you are a data geek.

 

[matti]

I was told I was a "visual mathematician" but it is still confusing, Goat!
What's ^ mean?
I'll copy the formula into a work sheet and see if that makes any sense.
Cheers.

P.s I do luv my refractometer too.... :wub:

 

[schooey]

^ means to the power of

so 2^2 = 2 squared = 4

 

[matti]

Thanks

 

[andrewg1978]

Hi all,

I just purchased a refractometer. I have a brew that has been going for 8 days and thought that I would try both hydrometer and refractometer but cannot get even close to the same reading...... Any ideas? or is it best not to measure after fermenation has started?

Thanks
Andrew

 

[alexbrand]

I just purchased a refractometer. I have a brew that has been going for 8 days and thought that I would try both hydrometer and refractometer but cannot get even close to the same reading...... Any ideas? or is it best not to measure after fermenation has started?

After fermentation has startet there's alcohol in the wort. So the refraction is not correct anymore. You need to convert it concerning the OG. The refractometer reading together with the known OG can be used to calculate the actual gravity. There are some formulas and some tools do do so. I have no English tool, German only, but have a look at this:

View attachment Brautools.zip

'Stammwrze' is OG, 'Bier/Jungbier' is refrac. reading, 'scheinb. Restextrakt' is what the hydrometer would say.

If there's no English tool I try to make one. Tell me.

Alex

 

[yardy]

i have neither a refractometer nor a hydrometer (it fell off the brewstand a few brews back) getting by without either quite easily.

 

[Maple]

Great tool Alex! I'll have to use a translate website to figure most of it out, but the tool is very good, just my foreign language skills that require work!

Maple

 

[alexbrand]

Great tool Alex! I'll have to use a translate website to figure most of it out, but the tool is very good, just my foreign language skills that require work!

Indeed, it's a nice tool. It's written by Earl Scheid, a German brew mate. He also wrote a reciepe maker for Open Office and Excel.

At the moment I'm putting these formulas into a 'new' progamme. So it'll be available in English as well. Give me some minutes...lol...

Alex

 

[andrewg1978]

Thanks for the download, looks like a good tool. But elas still can't work this one out. :angry:

Intial OG-1040 (5.3%)
after 8 days
reading with tap water - 0 brix have checked twice
reading with refactometer - 4.5brix (approx 1019) - have checked reading 3 times!
reading with hydrometer - 1010 - have checked reading twice


Any ideas?

NB - 22Ltrs x Coopers Int'l larger with 1kg BE2 @ 20deg

 

[bljpoad]

After fermentation has startet there's alcohol in the wort. So the refraction is not correct anymore.

I think this is the point that you are missing. The refractive index of water and alcohol are different. So when fermentation has started, you have alcohol present in the wort and can not get an accurate reading with a refractometer without compensating for this fact. Before fermentation there is no alcohol so there is no problem.
- Bez

EDIT: I need to watch my spelling!

 

[Stuster]

Intial OG-1040 (5.3%)

+1 to what Berwyck said. Just wondering what you mean by 5.3% here? :huh:

 

[andrewg1978]

+1 to what Berwyck said. Just wondering what you mean by 5.3% here? :huh:

5.3% is potential alcohol content,

you have alcohol present in the wort and can not get an accurate reading with a refractometer without compensating for this fact

sorry for the hard of learning!!! re-compensating for the alcohole that is present, how does one do this? Am I missing something?

Appreciate the help!!

 

[alexbrand]

sorry for the hard of learning!!! re-compensating for the alcohole that is present, how does one do this? Am I missing something?

Nothing to say sorry for. For compensating the refraction error you need the formula and a calculator. Or the above mentioned programme. It's almost ready, I just have to look up some English expressions. Just stand by.

Alex

 

[alexbrand]

So... here we go. I attatched the promised tool for using a refractometer during or after fermentation. It is just a BETARELEASE. So please tell me about problems. I'm not a programmer, so there may be many (runtime) errors in the programme. The calculated values themselves should be okay.

I still didn't find all the English expressions needed. Probably you can help me out...


View attachment RefractorBETA.zip

Alex

 

[Effect]

is it necessary to get a refractometer?

i mean what benefit am I going to get from having a refractometer (other than the ease of getting readings from small amounts of wort)? Am I able to find out the gravity reading with a refractometer during fermentation. From what Doc said in his inital post it seems to me that I can't? So why would I want one?

A hydrometer can measure the gravity of any liquid yeah? but refractometer only pre-ferment???

Please help :S

 

[the_fuzz]

is it necessary to get a refractometer?

i mean what benefit am I going to get from having a refractometer (other than the ease of getting readings from small amounts of wort)? Am I able to find out the gravity reading with a refractometer during fermentation. From what Doc said in his inital post it seems to me that I can't? So why would I want one?

A hydrometer can measure the gravity of any liquid yeah? but refractometer only pre-ferment???

Please help :S

I love my refractometer - Really only a benifit when doing AG - can't really see the point for a KKer

Very easy to get all your readings, taking readings straight from your wort running out of the mash tun is very handy

You can use it during ferment and after - just need to use the right calc's - They are in Beersmith

I only use the Hydrometer now to check colour and clarity

 

[Adamt]

You can get a good estimation of the fermenting wort gravity if you know the original wort gravity. Beersmith is really helpful for this.

 

[Frank]

A hydrometer can measure the gravity of any liquid yeah? but refractometer only pre-ferment???

As others have stated you can get conversions to work out the SG of wort + alcohol.
When your beer is finishing ferment, they are great to ensure the same reading is achieved for a couple of days, does not matter what the number is, or on what scale, as long as it is static. When you consistenly get the same number, then you can go back to your hydrometer for the final reading.