Accurate Refractometer Readings

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Accurate Refractometer Readings

Postby theotherone on Mon Jan 17, 2011 4:06 pm

I'm a refractometer newbie; I can only barely wrap my head around how exactly the darn thing works.

I've heard from a couple of folks that getting consistently accurate readings can be a bit difficult. I've had a good amount of success with mine so far, but there are times when I would like to know what I can do to ensure that my readings are as accurate as possible. One thing I've been doing is to time everything so that my samples cool for the exact same amount of time, and so that the temperature of the glass has the same amount of time to find equilibrium with the sample. The manual says to clean the sample well between each use with alcohol, and I was recommended to calibrate between each reading.

What works, and what doesn't? Please let me know. Vince can hopefully jump in on this too.
Jonathan S. Jarrow
Harbinger Coffee, LLC

"Happy Martinique! Hospitable land!
In a new world, you were the first
To gather and fertilize this delightful Asiatic berry,
And, in a French soil, to ripen its Ambrosia!
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Re: Accurate Refractometer Readings

Postby Jim Cleaves on Tue Jan 18, 2011 8:52 am

We calibrate before every session, just to be sure. And anyway it's so easy, why not?

The single greatest factor we find affecting consistent readings is sample temperature at the time reading is taken.

it's not how long the sample is cooled before reading- it's the temp itself. We find that a range of 18-21.9 C gives consistent readings.

If the ambient temp is above 80 F we use an ice water bath to get the sample in the porcelain cup down into the acceptable range
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Re: Accurate Refractometer Readings

Postby IanClark on Mon Jan 24, 2011 6:53 am

I'd just like to echo Jim here. In my experience the best thing you can do for your refractometry practice is to clean and calibrate every session. It works like a charm if you do. Apart from this, just allow your sample to cool properly make sure you're using properly filtered coffee and you should be good.
Ian Clark
Bridgehead
Ottawa, ON
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Re: Accurate Refractometer Readings

Postby theotherone on Mon Jan 24, 2011 5:34 pm

Thanks Jim and Ian. Great advice.
Jonathan S. Jarrow
Harbinger Coffee, LLC

"Happy Martinique! Hospitable land!
In a new world, you were the first
To gather and fertilize this delightful Asiatic berry,
And, in a French soil, to ripen its Ambrosia!
theotherone
 
Posts: 31
Joined: Wed Nov 10, 2010 2:14 am
full name: Jonathan Jarrow
company: Harbinger Coffee, LLC
: www.harbingercoffee.com


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