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How to calibrate a refractometre

Discussion in 'General Brewing Techniques' started by DrewCarey82, 5/5/18.

 

  1. DrewCarey82

    "Baron Hardmans" Chief brewer.

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    Posted 5/5/18
    Hey Guys.

    Anyone in the Sutherland area willing to show a dope how to calibrate one, got one love it but pretty sure its out, youtube clips have only confused me!

    Cheers in advance, happy to provide a 6 pack of james squires best :)

    Drew!
     
  2. MHB

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    Posted 5/5/18
    Just Googled the heading above, lots of step by step come up, a bunch of YouTube videos to so it cant be too hard find one.
    Most people just Zero it with pure/distilled water, if you wanted to get really fancy you could make up a test solution.
    Most are marked in Brix or Plato (SG optional), Just dissolve 100g of household white sugar in 900g of purified/distilled water, make sure its fully dissolved and you have a 10oP (or Brix) 1.040 test solution..
    Mark
     
  3. Brewno Marz

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    Posted 5/5/18
    Use tap water to calibrate, unless you have distilled water at hand.
    There is a screw on the top of the refractometer (maybe within a knurled knob) and you should have have a small screwdriver with the unit.
    With a few drops of tap water on the slide and looking through the eyepiece you turn the screw until the bottom of the blue shading is level with the bottom marking (1.000SG or 0%Brix). Calibration done. I find my refractometer needs calibration often and I always use tap water.
     
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  4. DrewCarey82

    "Baron Hardmans" Chief brewer.

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    Posted 6/5/18
    Okay cool, will do, cheers, just got confused with all the different types of solutions to use instead of water.

    And was 28 beers in lol.
     
  5. MHB

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    Posted 6/5/18
    Better to use pure water over tap water, I don't know what your tap water is like but anything dissolved in tap water will give a reading other than 0.000.
    I always have a carton of Pura Water, about $5/10L at woolies, I use it for drinking, working with yeast, when I'm making a cup of my favourite Tea (lapsang souchong)... and for calibrating Digital SG meters, cleaning pH electrodes.
    Mark
     
  6. Tony121

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    Posted 6/5/18
    Off topic but do you boil the Pura Water prior to using or use as is?
     
  7. MHB

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    Posted 6/5/18
    Pureau Water, sorry
    No not for most jobs, it is sterile. Only time I boil it is if I want close to Oxygen free.
    Mark
     
  8. Tony121

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    Posted 6/5/18
    Thanks Mark
     
  9. philrob

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    Posted 6/5/18
    I use distilled water. Just a few drops each time I use it is all it takes. Still using the bottle of water I first got about 7 or 8 years ago. Works for me.
     
  10. Brewno Marz

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    Posted 6/5/18
    Unlikely. The difference in specific gravity between distilled water and capital city tap water is negligible. Another home brew myth....
     
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  11. MHB

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    Posted 6/5/18
    Depends on what you call negligible, problem with errors is they accumulate.
    Same applies with weighing sugar/water to make a stock solution, if you know anything about measurement it pays to have a long hard look at how big your cumulative error is before trusting a reading.
    And like I said, I have ultra pure water on hand anyway, for that matter a 1L bottle of distilled water at woolies is only a couple of dollars, as prilrob said it would last for years if just used for calibration, less if you have a pH meter and rinse the probe between calibration standards/tests. Good practice as it makes the probe last longer.
    I have a digital refractometer and SG/density meter and can see the difference between tap and distilled.
    Use anything you like, but pure water is a better option.
    Mark
     
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  12. Brewno Marz

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    Posted 6/5/18
    Errors accumulate, yes, but in a single reading there is no accumulation. If you are seeing a definitive difference between your tap water and distilled water you should not be breweing with your tap water - or drinking it.
     
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  13. DrewCarey82

    "Baron Hardmans" Chief brewer.

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    Posted 9/5/18
    Cheers mate zero with whats out of the tap.
     
  14. Brewno Marz

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    Posted 9/5/18
    Yes! Consistency should be the goal. If you zero your refractometer with tap water everytime you will get consistency. You might be a 0.01% out on % ABV, but is that important? You don't pay excise!
     
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  15. S.E

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    Posted 10/5/18
    Looks like OP is happy using tap water but for anyone wanting to calibrate a refractometre with distilled water and can’t get to Woolies you could make some at home with a kettle and two clean dessertspoons.

    I’ve just tried it while making a cup of tea (PG Tips pyramid bags). Just hold one spoon over the spout when the kettle boils and catch the drips with the second spoon. I got about half a spoon before the kettle clicked off so plenty to calibrate a refractometre.

    What I do though is use wort as a test solution. At the end of a brew day I check my wort gravity with a hydrometer then check and if necessary calibrate the refractometre with a drop of wort from the hydrometer tube.
     
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  16. hellbent

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    Posted 10/5/18
    I check mine every brew using tank water and most times it needs adjusting.
     
  17. MHB

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    Posted 10/5/18
    Been thinking about it and tap water is probably fine for most people, I will keep using pure water because it always on hand and is (marginally) more precise.
    I also use a conductivity meter for a couple of odd jobs, believe me that's one instrument where the difference between tap water and distilled will really matter, so for me its a pretty important when I'm measuring stuff. Sometimes I use it to zero a turbidity meter to, again not something you can trust to tap water.
    If you have distilled/purified water on hand I would use it, if not I wouldn't get in a bunch but for a couple of dollars for several years supply it's worth it.
    Mark
     
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  18. wynnum1

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    Posted 10/5/18
    Just keep a bottle of same water for testing and if you get a different result then it needs adjusting.
     
  19. S.E

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    Posted 10/5/18
    Mark, if you check out my post above anyone can have enough distilled water on hand in a matter of minutes if they have a kettle and couple spoons.
     
  20. MHB

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    Posted 11/5/18
    Yep saw that, amazing how many ways there are to get to the same place.
    I'm a Lapsang Souchong man my self, not necessarily in teabags tho.
    Mark
     
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