# Refractometer Problem?



## Duff (3/6/06)

This is the 3rd brew in a row I've done where my refractometer is giving me a pre-boil reading equivilent to 97% efficiency :blink: 

I made a Dunkelweizen today OG:1.056. ProMash pre-boil is 1.044 (11.4 Brix). My refractometer read 14 Brix (1.054), my hydrometer reading was 1.045. This is after stirring the wort thoroughly for several minutes to ensure even distribution of sugars.

Now, simple answer is it's not calibrated correctly, I've checked several times and it is fine with boiled, cooled water. Further, when the boil has finished and the wort cooled (as with the other two) it gives me the correct anticipated OG. Has anyone had any issues like this with their refractometers? It's quite off putting when you are second guessing in your mind about the upcoming hop additions.

Cheers.


----------



## mika (3/6/06)

Is it just that your refractomer does not have ATC (Automatic Temp Compensation) and you're seeing an inflated reading.
Did you cool the sample when you checked with the hydrometer ?


----------



## Duff (3/6/06)

mika_lika said:


> Is it just that your refractomer does not have ATC (Automatic Temp Compensation) and you're seeing an inflated reading.
> Did you cool the sample when you checked with the hydrometer ?



It has the ATC and the hydrometer sample was cooled. This has only occured for the last 3 brews, before that no problem.


----------



## mika (3/6/06)

If the reading was good once the wort had cooled it would have to point to a problem with the ATC or something temp related :unsure: I'm still waiting for my refractometer, have to verify my damn paypal account :angry: so can't offer anymore advice.


----------



## pint of lager (3/6/06)

Have you calibrated the refractometer to zero with distilled water? The easiest way to obtain distilled water is to use a few drops of condensed steam from the kettle lid, or hold a spoon in the vapour path of the steam escaping. Also check that your hydrometer floats at 1.000 in water at 20 deg C. 

You could also check both the hydrometer and refractometer with a known sugar sample. 100 gms of sugar dissolved in 1 litre of water is supposed to give an sg of 1.040. Have never measured this myself.

Is the glass landing and the flip down plastic cover spotless? If wort has at some time dried on the cover (both top and bottom sides) or the glass bed, this would give you an incorrect higher reading. Is the cover seating flat as it has always done in the past? If there is dried wort in the hinge, this may be causing it to not seat correctly.


----------



## Gulf Brewery (3/6/06)

Duff said:


> mika_lika said:
> 
> 
> > Is it just that your refractomer does not have ATC (Automatic Temp Compensation) and you're seeing an inflated reading.
> ...



We have had erroneous readings in the brewery using a refractometer. I think the ATC refers to correction for the ambient temperature, not the wort sample. We find the safest and most accurate way is to cool the sample and then measure.

Cheers
Pedro


----------



## Zwickel (3/6/06)

Gday mates,

the ATC does not correct the temp of the sample.
The ATC avoids only an offset of zero-calibration.
Thats only a mechanical balancing of the zero point.

Anyway that ATC works only within a certain range.
If you left the refractometer laying in the sunlight, youll not get a proper reading.
The ATC will run out of range.
Also if the temp of the sample is too high.

Thats a physical matter, a cold samples density is higher than that of a hot one.
A refractometer cantt correct the sample!

To get proper readings, the refractometer itself should be at 20C.

just my 2 cnt.


----------



## Darren (3/6/06)

I have been dunking my refractometer into the boiling wort waiting 15 seconds and then reading. It is always the same as the hydrometer.
I would check your hydrometer as it the most likely to break and be reading incorrectly.

cheers

Darren


----------



## Zwickel (3/6/06)

Darren said:


> I have been dunkimg my refracto into the boiling wort waiting 15 seconds and then reading. It is always the same as the hydrometer.



Sorry Darren,

a hot wort, has never the same density as a cold one.
The refractometer has no device to adjust its optical lens to another refraction.
It only can compensate the drift of zero line. 

just my 2 cent


----------



## Darren (3/6/06)

Zwickel said:


> Darren said:
> 
> 
> > I have been dunkimg my refracto into the boiling wort waiting 15 seconds and then reading. It is always the same as the hydrometer.
> ...




No need to be sorry Zwickel,

The wort reaches ambient almost immediately as it is essentially only about 100 microlitres in volume
If it is too hot the line is blurred, as it cools the line becomes sharper.

Done it dozens of times now. Try it yourself.


cheers

Darren


----------



## mika (3/6/06)

Zwickel, Darren, would be interesting to take a measurement the way the other does it and then do it your way and let us know if there is any difference in the reading.


----------



## Darren (3/6/06)

mika_lika said:


> Zwickel, Darren, would be interesting to take a measurement the way the other does it and then do it your way and let us know if there is any difference in the reading.




Mika,

When I first got my refractometer I was sooo careful not to damage it and also use it as per instructions. As time went on I got lazier and lazier. In the end I just dunked it in and it worked.
I always take a flame-out (hot with refractometer) and post chill (with hydrometer) They always read within the limit of sensitivity of either device (never more than 4 SG points apart).

Just my observations.

cheers

Darren

I should have added. Most false results from a refractometer come from not washing the prism or lid.
If it is slightly wet from water or wort it will greatly skew your results.


----------



## Zwickel (3/6/06)

Darren,

the compound of the device will cool down your sample very quickly, thats why your reading is close to the real value.
But... dont dip the refractometer into the hot wort or never leave it lying in the sunlight.

sure your readings will be far away from its original.

when the horizon is unsharp, the reason is mostly a cloudy wort.

You may take an experiment. Take clear water and add some powder.
Youll get a very unsharp horizon.

To resolve that problem, you may press the lid to the device, so the layer of wort becomes thinner and the horizon will sharpen.

Cheers


----------



## Darren (3/6/06)

Hi Zwickel,

I have watched the line become sharper as the wort within the chamber cools. Try it yourself. Reads the same 20 seconds afterwards as it does 10 minutes later.

BTW, Cloudy wort will not effect SG or Refractive index.

cheers

Darren

I agree that leaving the whole unit in the sunlight will adversely heat it up and cause problems.


----------



## Zwickel (3/6/06)

Darren said:


> BTW, Cloudy wort will not effect SG or Refractive index.


thats absolutely right.
but the clarity of the sample is responsible for the sharpness.

lets have a beer :beer:


----------



## Darren (3/6/06)

Zwickel,

:beer:

cheers

Darren


----------



## sqyre (3/6/06)

Hi, i've just been skimming through the posts on refractometer problems and a few posts mention the word "DUNKING". 
What ever you do dont submerge any part of your refractometer into any liquid as the seals in these things arn't the best. As soon as you get any moisture inside them they are stuffed.

I have been using refractometers for about 10 years (for testing coolant levels in machinery) and the biggest cause of damage is people submering the refractometers in the water.( even only the tip. )

The best way to take a reading ( in my experience) is to remove a small sample in a cup or whatever... and leave to reach room tempreture before testing. Apply 2-3 drops to the glass by dipping the end of a clean spoon or something into the cooled wort sample and use the drops off the end of the spoon.

To keep the reading acurate all the readings you take after the first reading should be close to the same tempreture as the first reading you took. (this also applies to calibration, but not sure how you guys do that as we calibrate to the water before the addition of soluble oils,etc.)

Hope this helps... :blink:


----------



## Zwickel (3/6/06)

Hi sqyre,

thats absolutely my position :super:


----------



## Darren (3/6/06)

sqyre said:


> Hi, i've just been skimming through the posts on refractometer problems and a few posts mention the word "DUNKING".
> What ever you do dont submerge any part of your refractometer into any liquid as the seals in these things arn't the best. As soon as you get any moisture inside them they are stuffed.
> 
> I have been using refractometers for about 10 years (for testing coolant levels in machinery) and the biggest cause of damage is people submering the refractometers in the water.( even only the tip. )
> ...




Sqyre,
Interesting post. I have had my brewing hydrometer for at least two years and have dunked it many times. It is just the tip, the same thing that you drop your oil on.
Btw, I have used lab refractometers to measure sucrose and salt solutions for 20 or more years. I would never be stupid enough to submerge the whole thing in the fluid.

Also, water on the lens will not be a problem with oil as the two don't mix. Water on the lens with wort will make a considerable difference.


cheers

Darren


----------



## Zwickel (3/6/06)

Darren,
it also depends on the quality of the device.

Some of the very cheap one dont allow to get dunked into the wort. Not even the tip of it.

Maybe you are owner of a very good one, so you are lucky.

But other hand, better not to advice anyone to do the same, some of that equipment will die very quickly.

Just my 2 cnt.


----------



## Ross (4/6/06)

Zwickel said:


> Darren,
> it also depends on the quality of the device.
> 
> Some of the very cheap one dont allow to get dunked into the wort. Not even the tip of it.
> ...



Wise words Zwickel - dipping your refractometer into hot wort is fool hardy - just because you've never had a problem, doesn't make it safe practice - Darren, you amaze me at times  

cheers Ross


----------



## johnno (4/6/06)

Well i have never dunked mine in the hot wort, but i was using a large spoon to just scoop up wort while the boil was on and pouring it all over the lens.

Worked ok like that for the first 2-3 brews then it started getting blurry readings.

Now I have to pour some wort in a cup an let it sit for a while then use the dropper and put 2-3 drops on the lens.

This is annoying as it is hardly taking a reading instantaneously.

As bought up in chat last night.

The ones we use are just cheap versions of proper, more able equipment.

Long live cheap junk.
johnno


----------



## BrissyBrew (4/6/06)

You state the last 3 brews have been off what have you been brewing? Are we talking stout? or something dark?


----------



## Ross (4/6/06)

johnno said:


> This is annoying as it is hardly taking a reading instantaneously.



Johnno, 

If used correctly by just using the dropper & just adding a couple of drops, the mass of the unit will pretty well instanly bring the sample within the temperature compensating limts of the unit & you should have no problems, unless the model you bought hasn't got ATC.


cheers Ross


----------



## normell (4/6/06)

So are these meters any use to non AG brewers.
My brewing is mostly ESB fresh wort packs now, with some extra hops added into secondary (thanks Ross), but an extra shiny bit of gear woundn't go astray, so come on Guy's, convince me that I need one


----------



## Ross (4/6/06)

normell said:


> So are these meters any use to non AG brewers.
> My brewing is mostly ESB fresh wort packs now, with some extra hops added into secondary (thanks Ross), but an extra shiny bit of gear woundn't go astray, so come on Guy's, convince me that I need one



Norm,

Very simple to check the starting & progressive gravity of your fresh wort kit with just a few droplets of wort. No hassles from CO2 clinging to your hydrometer samples - Also far less prone to breakage than using your hydrometer. But the real benefit to the ag'er is being able to read hot wort samples instantly.

Ooh & they look dead cool as well  

Cheers Ross


----------



## Gulf Brewery (4/6/06)

Ross said:


> If used correctly by just using the dropper & just adding a couple of drops, the mass of the unit will pretty well instanly bring the sample within the temperature compensating limts of the unit & you should have no problems, unless the model you bought hasn't got ATC.
> 
> cheers Ross



Ross

Have a look at my previous post (and also Zwickel's and sqyre's) in this thread - the ATC is not correcting the sample temperature and we have found you must cool the sample to get an accurate reading

Pedro


----------



## mika (4/6/06)

Normell, this says it all



Ross said:


> ....... with just a few droplets of wort......



thus you waste less precious beer :beer: 

And this may also have something to do with it h34r: 



Ross said:


> Ooh & they look dead cool as well


----------



## johnno (4/6/06)

normell said:


> So are these meters any use to non AG brewers.
> My brewing is mostly ESB fresh wort packs now, with some extra hops added into secondary (thanks Ross), but an extra shiny bit of gear woundn't go astray, so come on Guy's, convince me that I need one



Normell,
If you are mainly doing the fresh wort packs there is hardly a need for a refractometer.
A hydro reading is all you need.

If you ever go AG, sure you may find one handy then.

Save yourself the money. Even better buy 2 fresh wort packs with it.

cheers
johnno


----------



## Ross (4/6/06)

Gulf Brewery said:


> Ross said:
> 
> 
> > If used correctly by just using the dropper & just adding a couple of drops, the mass of the unit will pretty well instanly bring the sample within the temperature compensating limts of the unit & you should have no problems, unless the model you bought hasn't got ATC.
> ...



I never had a problem when just using the little eye dropper that comes with the refrac (I used to just draw enough for the sample, so I guess it cooled pretty rapidly), but having lost it, I now take a sample with a teaspoon & pour on the lense. I've found like you & others, in this case it needs to cool a little to get an accurate result. I take one reading & then follow with one from the same sample a minute later for confirmation. 

cheers Ross


----------



## Kai (4/6/06)

So far I haven't had inaccurate readings, from putting hot wort from a pipette directly onto the lens of my non-ATC refrac.


----------



## Zwickel (4/6/06)

Kai said:


> So far I haven't had inaccurate readings, from putting hot wort from a pipette directly onto the lens of my non-ATC refrac.



So, you may do a test: fill up an eyedropper with hot wort and take one sample of it instantly; then leave the eyedropper with the rest of wort alone, til the temp has reached room temp and measure again.
Sure youll get two different readings.

One hand, a hot wort cannot have the same density as a cold wort, thats a physical matter, if your refracto. shows the same, it has to be wrong.

Other hand, as Ross has mentioned, the mass of the refracto. will dissipate the temp of the sample, but anyway it heats up the most sensitive part of the meter, I wouldnt rely on it.

Cheers


----------



## sah (18/12/06)

I've just brought a refractometer and have used it for 3 brews. I'm having a couple of problems.

Yesterday the after boil reading was 18.3% brix (1.074). I had let the sample cool. Today the wort reads 17.5% brix (1.070).

I'm also finding that the pre boil reading is indicating that I've achieved about 82% efficiency, according to Beersmith's calculations, the immediate after boil reading was indicating 78% efficiency and today's reading indicated 74% efficiency.

The brew the day before (a wit) pre boil reading 1.064 (81% efficiency) post boil reading 1.071 (70.6% efficiency)

For the pre versus post boil readings I'm guessing incorrect boil off and volume estimates are mucking things up. However its the first problem I'm more concerned with. That is, different readings immediately after the boil versus the next day when it has completely cooled. Don't forget I'm letting the samples cool.

Does anyone have some words of wisdom?

Thanks in advance.

regards
Scott


----------



## Darren (18/12/06)

SAH,

Have you dried your refracto between uses? Minute amounts of water will cause huge fluctuations in refracto readings.

cheeers

Darren


----------



## sah (18/12/06)

Yes I forgot to mention that Darren. I dried both lense and lid thoroughly with a soft paper towel.

Scott


----------



## Darren (18/12/06)

sah said:


> Yes I forgot to mention that Darren. I dried both lense and lid thoroughly with a soft paper towel.
> 
> Scott



SAH,

could it be where you "took" the line? Maybe brewday maths? 4 sg points are not really worth worrying about anyhow.

cheers

Darren


----------



## sah (18/12/06)

Hi Darren,

I had an assistant yesterday who also check the reading and concurred. The maths was done by Beersmith. I take your point about not worrying too much about 4 points.

All the best.
Scott


----------



## Simon W (18/12/06)

Is it possible that after sitting for a while, heavier sugars have fallen to the bottom, so the upper levels of the wort are slightly thinner? Maybe a stir of the wort will bring he reading back up? Just a thought.


----------



## Stuster (19/12/06)

Probably a silly question, but what volume are you using for your post-boil efficiency? In kettle or into fermenter? :unsure: 

Has it started fermenting?


----------



## PostModern (19/12/06)

Hi Scott,

Did you calibrate your refractometer? ie, check that it reads 0 with tap (or ideally distilled) water? I gave mine a test of tap water then another with 10g of sugar in 100ml of water and it read bang on 10, so I know mine is at least as accurate as my scales. (EDIT: oops, just read PoL asked Duff this in post #5)


----------



## redbeard (19/12/06)

In a recent ag brew, i found the start of 1st sparge compared to the end to be very different, let alone the 2nd sparge start & end ... perhaps thats the point - the average ?


----------



## Simon W (19/12/06)

> ...then another with 10g of sugar in 100ml of water and it...



That didn't look right so I've been hunting and I think it's supposed to be 10g sugar + 90g water(90ml)
Everything I can find about the Brix scale says its this way, some state it as 10g per 100g solution(water+sugar), others a percentage, eg. 1g = 1% by weight of sugar, therefore 100deg Brix = 100% = pure sugar, 50deg = 50% = 50g sugar 50ml water.
10g in 100g water would be (10g/(10g+100g))*100 = 9.09 percent by weight of sugar or 9.09Brix

Can anyone confirm this?


----------



## sah (19/12/06)

Simon W said:


> Is it possible that after sitting for a while, heavier sugars have fallen to the bottom, so the upper levels of the wort are slightly thinner? Maybe a stir of the wort will bring he reading back up? Just a thought.



Hi Simon,

I took the pre boil reading after stirring, however this reading is giving me the higher result so the theory doesn't hold.

The post boil sample was collected very soon after flame out. There is still a lot of turbulence at this time.

The sample for the wort cube may well not be uniform.

Thanks for highlighting this.

regards
Scott


----------



## sah (19/12/06)

Stuster said:


> Probably a silly question, but what volume are you using for your post-boil efficiency? In kettle or into fermenter? :unsure:
> 
> Has it started fermenting?



Stuster,

You know there's no such thing as a silly question. Here's the story. I've setup my equipment in Beersmith so that it knows the final volume is 46L of that 14L is added after the boil.

In Beersmith's efficiency calculator it has a section for efficiency into boiler. That bit is easy. It also has a section for "Brewhouse efficiency based on target volume". Here you enter the actual OG, that is, after dilution or into the fermenter.

No it hasn't started fermenting after 12 hours. This is very unusual for US-56. I aerated. It's at 1.047. I've upped the temperature a fraction. I'm also having problems getting some coopers pale yeast to finish off at the moment.

Thanks for all the help.

Scott


----------



## sah (19/12/06)

PostModern said:


> Did you calibrate your refractometer? ie, check that it reads 0 with tap (or ideally distilled) water? I gave mine a test of tap water then another with 10g of sugar in 100ml of water and it read bang on 10, so I know mine is at least as accurate as my scales. (EDIT: oops, just read PoL asked Duff this in post #5)



It's bang on 0 for tap water.

Cheers PM.

regards
Scott


----------



## albrews (19/12/06)

SAH said:


> It's bang on 0 for tap water.
> 
> Cheers PM.
> 
> ...


hi, yes, your brixmeter is giving reverse indication as to what is expected, in that cooled wort is denser and should give higher brix (sg) compared with hot wort. could you have had the samples mixed up?
did you use the same light source for the measurements? ie sunlight , or fluro.

cheers al


----------



## sah (19/12/06)

albrews said:


> hi, yes, your brixmeter is giving reverse indication as to what is expected, in that cooled wort is denser and should give higher brix (sg) compared with hot wort. could you have had the samples mixed up?
> did you use the same light source for the measurements? ie sunlight , or fluro.
> 
> cheers al



Gday Al,

No chance of mixing up the samples. They were taken with a dropper (pipette). Same light source.

regards
Scott


----------



## sah (19/12/06)

SAH said:


> No it hasn't started fermenting after 12 hours. This is very unusual for US-56. I aerated. It's at 1.047. I've upped the temperature a fraction. I'm also having problems getting some coopers pale yeast to finish off at the moment.



I've just had a closer look at this. It looks like the US56 went through its growth stage ok. There was a good yeast cake. So I gave it a stir and gave them a stern talking to about slacking off on the job. Oh yeah, I also upped the temperature.

I'm counting on these brews to finish out before chrissy :excl:

Good day.

Scott


----------



## Asher (19/12/06)

Scott

How did you cool your first sample?
I've heard (from somebody sensible ) that whilst dropping directly onto the cool lense some steam is given off. thus giving a slightly higher than 'true' reading.... Not sure it would add up to 4 gravity points though.

Asher for now


----------



## PostModern (19/12/06)

Simon W said:


> That didn't look right so I've been hunting and I think it's supposed to be 10g sugar + 90g water(90ml)
> Everything I can find about the Brix scale says its this way, some state it as 10g per 100g solution(water+sugar), others a percentage, eg. 1g = 1% by weight of sugar, therefore 100deg Brix = 100% = pure sugar, 50deg = 50% = 50g sugar 50ml water.
> 10g in 100g water would be (10g/(10g+100g))*100 = 9.09 percent by weight of sugar or 9.09Brix
> 
> Can anyone confirm this?



Hell, then my refractometer must be out. (But then again, my scales only have 2g accuracy, so I could have fluked it).

EDIT: Wikipedia has this to say:



> A 25 Bx solution has 25 grams of sucrose sugar per 100 grams of liquid. Or, to put it another way, there are 25 grams of sucrose sugar and 75 grams of water in the 100 grams of solution.


----------



## sah (19/12/06)

Asher said:


> How did you cool your first sample?
> I've heard (from somebody sensible ) that whilst dropping directly onto the cool lense some steam is given off. thus giving a slightly higher than 'true' reading.... Not sure it would add up to 4 gravity points though.



I collected with a dropper. Put some directly on the refractometer lense, took a reading. Let it cool on the lense took a reading. Cleaned the lense and put another couple of drops on from the dropper, now cooled. All three get the same result.

regards
Scott


----------



## tangent (19/12/06)

i've found that stratification happens quicker than i expected and my readings were all over the place, depending if i took a reading from the top or the bottom of the wort. The only way i found to stop it was to take one during full boil so heaps of motion or just after transfer to the fermenter.


----------



## Screwtop (19/12/06)

PostModern said:


> Hell, then my refractometer must be out. (But then again, my scales only have 2g accuracy, so I could have fluked it).
> 
> EDIT: Wikipedia has this to say:




But 10g of sugar aint 10g of sucrose????


----------



## sah (19/12/06)

SAH said:


> I've just had a closer look at this. It looks like the US56 went through its growth stage ok. There was a good yeast cake. So I gave it a stir and gave them a stern talking to about slacking off on the job. Oh yeah, I also upped the temperature.
> 
> I'm counting on these brews to finish out before chrissy :excl:



It just goes to show. Sometimes a stern talking to is all they need. The US56 brew has a good thick krausen now and the other one with the Coopers pale yeast has dropped from 7% to 6% brix today. You beauty! That's the first time since I've been checking that I've had a fermentation stall. A degree or two at the lower end can really make a difference.

regards
Scott


----------



## albrews (19/12/06)

SAH said:


> It just goes to show. Sometimes a stern talking to is all they need. The US56 brew has a good thick krausen now and the other one with the Coopers pale yeast has dropped from 7% to 6% brix today. You beauty! That's the first time since I've been checking that I've had a fermentation stall. A degree or two at the lower end can really make a difference.
> 
> regards
> Scott
> ...


----------

