Author Topic: I finally got myself a refractometer ....  (Read 1626 times)

Offline Kaiser

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I finally got myself a refractometer ....
« on: February 02, 2010, 02:17:07 PM »
…. and have been busy on reading up on how they work. Pretty clever I must say. The ATC function, for example, is simply done by placing the scale on a bi-metal strip. This shifts the scale up and down based on the temperature of the refractometer itself.

The measurement of refractive index is based on “total internal reflection”. Depending on the refractive index of the test solution you are either looking at the blue background of the prism (total internal reflection) or through the sample and lid at the light source. The refractive index changes at what angles that happens and that’s why you are seeing a transition from white to blue. That also allows a very simple design.
Kai

« Last Edit: February 02, 2010, 02:27:29 PM by Kaiser »

Offline bluesman

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Re: I finally got myself a refractometer ....
« Reply #1 on: February 02, 2010, 04:28:48 PM »
Well it's about time Kai.  ;D

You're going to love this tool. I promise.  ;)
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Offline tom

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Re: I finally got myself a refractometer ....
« Reply #2 on: February 02, 2010, 05:10:22 PM »
It really is about time you got scientific about brewing!  ;)
Brew on

Online Thirsty_Monk

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Re: I finally got myself a refractometer ....
« Reply #3 on: February 02, 2010, 08:55:59 PM »
Well it's about time Kai.  ;D

You're going to love this tool. I promise.  ;)

+1 It is nice tool to have around.
It makes gravity reading much easier.
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Offline lonetreedavid

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Re: I finally got myself a refractometer ....
« Reply #4 on: February 02, 2010, 10:27:56 PM »
Sorry for my stupidity! But what's a refractometer?  I have been looking for a digital hydrometer - would that be similar to a refractometer. Please could you post a link where I could see one - and maybe, buy.
Thanks David

Offline Kaiser

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Re: I finally got myself a refractometer ....
« Reply #5 on: February 03, 2010, 08:04:18 AM »
Not a dumb question at all.

Generally speaking a refractometer is a device that measures he refractive index of a substance. The refractive index is a measure of how much light is bent when it travels from air (or another substance) into the particular substance being measured.

We home brewers use refractometers that are designed to measure the refractive index of sugar solutions. Since that index and the sugar content are related one can determine the sugar content simply by measuring the refractive index. That is done though a scale that is calibrated to the Brix scale. Another property that is strongly related to sugar content is specific gravity and that is measured with a hydrometer. For these devices too the scale can be marked as sugar content (Brix, Balling, or Plato).

Refractometers are not necessarily more precise than hydrometers but they allow sugar content (or specific gravity) measurements on very small samples (few drops) and don’t require cooling a large sample. The sample quickly takes on the temperature of the refractometer which is the temperature that is used in the temperature correction of the reading. This is necessary since the refractive index of a sugar solution also changes with temperature.

I recommend a refractometer only as a supplement to a hydrometer and not as a replacement. Determining the specific gravity of fermented beer is a bit tricky since the alcohol affects the refractive index differently than it affects the specific gravity.

Here is a good BYO article: http://www.byo.com/stories/projects-and-equipment/article/indices/29-equipment/1343-refractometers

Kai

Offline lonetreedavid

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Re: I finally got myself a refractometer ....
« Reply #6 on: February 03, 2010, 12:09:27 PM »
Thanks for the background information. Could you possible recommend an actual model of refractometer.
thanks
David

Offline bluesman

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Offline lonetreedavid

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Re: I finally got myself a refractometer ....
« Reply #8 on: February 03, 2010, 12:16:50 PM »
Thanks

Offline Kaiser

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Re: I finally got myself a refractometer ....
« Reply #9 on: February 03, 2010, 12:18:28 PM »
This is the same that cynmar sells: http://cynmar.com/item_detail.aspx?ItemCode=21036370

And since I commonly buy stuff there I got it from them.

Kai

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Re: I finally got myself a refractometer ....
« Reply #10 on: February 03, 2010, 01:17:33 PM »
It's also the same one frequently sold on eBay for $25-30. ;)
Beer is like porn. You can buy it, but it's more fun to make your own.
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Offline blatz

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Re: I finally got myself a refractometer ....
« Reply #11 on: February 03, 2010, 01:20:00 PM »
It's also the same one frequently sold on eBay for $25-30. ;)

+1 - giddy up!
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Online Thirsty_Monk

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Re: I finally got myself a refractometer ....
« Reply #12 on: February 03, 2010, 01:33:52 PM »
I know a lot of people shop on ebay but I just can not do it.
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Offline tygo

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Re: I finally got myself a refractometer ....
« Reply #13 on: February 03, 2010, 01:41:22 PM »
I know a lot of people shop on ebay but I just can not do it.


Why not?  I don't do it a lot but I've found some good deals on there before.
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Offline tygo

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Re: I finally got myself a refractometer ....
« Reply #14 on: February 03, 2010, 07:38:22 PM »
Clint
Wort Hogs

Fermenting: Wit
On Tap: Lucifer's Hammer Golden Strong Ale, Dopplebock, Old Fuzzynut's Ale