Refractometer usage

[Black n Tan]

Old saying... poor workman blame tools.

Not sure that saying is apt in this situation. If you have something helpful to add please do.

 

[Killer Brew]

Think I might park mine between brew days. Am finding the converted calcs very unreliable. Just finished tracking the ferment of a pale ale calibrating before every reading. Final one was 6P degrees after starting at 13P degrees (cross checked with hydrometer). The converter suggests that this is a FG of 1007. Hydrometer check is showing 1013. Double checked both to make sure. Hell of a difference.

 

[Lyrebird_Cycles]

Using the right calculation will give you the right result.

If you use the Brewer's Friend calculator and put in a correction factor appropriate for attenuated wort (0.90) it gives an equivalent FG of 3.35 oP (1013).

I explained in #15 above why the correction factor changes with attenuation.

 

[RdeVjun]

Maltplat, IMO the tiny air bubbles in your refractometer sample don't seem to interfere with the actual result, however they do seem to lead to some blurriness in the blue edge which makes it difficult to instantly note the result.
With respect to the variability, a cooled hydrometer sample at these points would have been be helpful- I'm not convinced the wort draining from the lautering operation is completely homogeneous and, for what ever reason a sharp rise in SG toward the end is not uncommon in my experience, so what you measured may in fact be real.
I personally find that the two instruments complement each other brilliantly, its hard to see what the fuss is all about.

 

[Mardoo]

I'd agree. Granted, a refractometer is not a sonic screwdriver, but it's also not like the last few generations of brewers, winemakers, beekeepers and mechanics (among others) have been using the wrong tool and just didn't know it.

If there's one thing I've learned from brewing, it's that certainty can be a process of estimation. And sometimes, our estimations don't fit reality. It's a weird feeling when I get a reading that makes no sense, but tracking back through the processes usually yields an explanation.

And thanks, RdeVjun, for that one. You've got me thinking more about weird readings. They're not always operator error.

However sometimes they are device error. That's why I believe bodging together brewing systems can be just fine, but spend as much as you can afford on measuring devices.

 

[Killer Brew]

Using the right calculation will give you the right result.

If you use the Brewer's Friend calculator and put in a correction factor appropriate for attenuated wort (0.90) it gives an equivalent FG of 3.35 oP (1013).

I explained in #15 above why the correction factor changes with attenuation.

Ok, will check that out. Have been using a PDF which cross references starting Plato gravity with current (so no correction factor). Had assumed all of the calculators worked the same. Wrongly obviously.

Is there then somewhere a list of wort correction factors based on the stage of fermentation or is this the required math you speak of?

Actually, don't worry. Found it. Will read through this one tonight and see if I can work it out.
http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/

 

[Elz]

Does anyone use the refractometer tool available in Beer Smith 2. It seems to work well for me, in that I am mostly hitting numbers expected. I did have to calibrate the software when first setting it up with a hydrometer measure. If anything my FG seem to be too low; that is expecting 1.010 and Beer Smith calculating 1.006-7

 

[Lyrebird_Cycles]

Is there then somewhere a list of wort correction factors based on the stage of fermentation or is this the required math you speak of?

Actually, don't worry. Found it. Will read through this one tonight and see if I can work it out.
http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/

No that doesn't have the correction factors for worts at different attenuations, as far as I know no-one has published them. I use ones I worked out myself.

I've seen a reference to something in Kunze, I am chasing down a copy so I can cross check it. Once I've done that I will write something up.

Does anyone use the refractometer tool available in Beer Smith 2. It seems to work well for me, in that I am mostly hitting numbers expected. I did have to calibrate the software when first setting it up with a hydrometer measure. If anything my FG seem to be too low; that is expecting 1.010 and Beer Smith calculating 1.006-7

Is there any tool in Beersmith that works properly? If so I haven't found it. I use Beersmith and quite like the program, but the calculators are all useless IME.

 

[Mardoo]

No that doesn't have the correction factors for worts at different attenuations, as far as I know no-one has published them. I use ones I worked out myself.

Care to publish them? I'd pay for that.

 

[Killer Brew]

No that doesn't have the correction factors for worts at different attenuations, as far as I know no-one has published them. I use ones I worked out myself.

I've seen a reference to something in Kunze, I am chasing down a copy so I can cross check it. Once I've done that I will write something up.


Is there any tool in Beersmith that works properly? If so I haven't found it. I use Beersmith and quite like the program, but the calculators are all useless IME.

That would be great. Thanks.

 

[MHB]

Don't laugh, I came very close to scoring a Hewlett Packard GC-MS package on Ebay a few years ago for under $7k. Probably a good thing I missed out, would very likely have been a source of domestic disharmony.

Not just the cost ($7k), had one of these at TAFF when doing Chem Dip, the lecturers scheduled all the HPLC/GC pracks into a very narrow window.
Apparently it took a couple of days to stabilise the vacuum in the MS and it spent the whole time sniffing ultra high purity Helium, worked out something like $100/day just to turn it on.
But OH what a toy, do some stuff that would startle you, we were looking at second and third order DDT degradation products in breakfast cereal, comparing "Organic" with just the regular stuff.
Mark

 

[Lyrebird_Cycles]

Care to publish them? I'd pay for that.

Once I've had a chance to check Kunze I will write something up and post it to a thread here.

I cobbled the information together from a bunch of disparate sources and did some analytical work to back it up, I'd prefer to check all available sources before going public.

 

[Lyrebird_Cycles]

Not just the cost ($7k), had one of these at TAFF when doing Chem Dip, the lecturers scheduled all the HPLC/GC pracks into a very narrow window.
Apparently it took a couple of days to stabilise the vacuum in the MS and it spent the whole time sniffing ultra high purity Helium, worked out something like $100/day just to turn it on.
But OH what a toy, do some stuff that would startle you, we were looking at second and third order DDT degradation products in breakfast cereal, comparing "Organic" with just the regular stuff.
Mark

Yeah I set the GCs in the lab in Perth up (we had three: one for alcohol, one for diacetyl and a back up in case one of the first two failed*). We used a lot of expensive gas.

* That sounds stupid except for the time we walked in one morning and the main control board in the alcohol GC had literally gone into meltdown: there was a pool of solder and components below it. We were back up and running in about an hour. Since bottling downtime was $20k per hour and these are primary checks, that was worth the price of the spare GC.

 

[MHB]

It's been a while but
I think the slow bit was waiting for the high vacuum diffusion pump to settle down, if you had multiple units on a manifold it would make booting up pretty quick.
Mind you TAFE didn't have the newest models of anything - I remember one machine that was Pre-Doss, instructions had to be loaded in its own very unique language, the ICP literally fell off the back of a truck, got refurbished and sold to TAFE cheap.

Some of the newer generation of analytical equipment is spectacular, just wish it wasn't so stupid expensive (translate as I don't get to play with it!)
Mark

 

[malt junkie]

I thought a Mass Spec could analyze the lot in one go; ie: alcohol, IBU, Bacteria or at least run them consecutively.

 

[Lyrebird_Cycles]

Mind you TAFE didn't have the newest models of anything - I remember one machine that was Pre-Doss, instructions had to be loaded in its own very unique language, the ICP literally fell off the back of a truck, got refurbished and sold to TAFE cheap.

Some of the newer generation of analytical equipment is spectacular, just wish it wasn't so stupid expensive (translate as I don't get to play with it!)
Mark

Tell me about it: in the same lab as the 3 GCs we had an Anton Paar densitometer so old it had a Nixie tube display.

Image is a counter timer with Nixies, couldn't find an image of the AP.

 

[Lyrebird_Cycles]

I thought a Mass Spec could analyze the lot in one go; ie: alcohol, IBU, Bacteria or at least run them consecutively.

Per the above, I didn't buy the GC MS, the GCs in the lab mentioned used flame ionisation detectors IIRC.

 

[Lyrebird_Cycles]

Rather than continuing to kidnap this thread with my ravings, I have started a new thread:

http://aussiehomebrewer.com/topic/92065-towards-an-understanding-of-refractometers-in-wort-and-beer/#entry1398654

enjoy.