Refractometer problem

[Lowlyf]

Ay lads,

I bought a refractometer off ebay and configured it to 0.000 with distilled water. I did have to change the little dial so I thought it was working. I took an SG of 1.065 and then left it. When it came to check the FG it said 1.035. At this stage I thought that wasn't right so I checked the beer with my hydrometer. 1.012.

I just did a IIPA which started at 1.075 and my hydrometer says today 1.010 huge beer ay? Well my refractometer read 1.035ish so what the bloody hell?

 

[barls]

are you allowing for the correction factor due to the alcohol in solution?

 

[bradsbrew]

You have to do a calc once it has started fermenting

https://www.brewersfriend.com/refractometer-calculator/

 

[Lowlyf]

Hmmm. Not sure how it bloody works

 

[manticle]

Alcohol affects the reading so either use it to read wort gravity (not beer) OR use a chart like the one brad posted or an online conversion calculator

 

[Lionman]

Once its started fermenting, you need to know the OG to work out the SG using a refractometer.

There are a bunch of online calcs to help you. They are all slightly different but in the same ball park.

https://www.northernbrewer.com/learn/resources/refractometer-calculator/
https://www.brewersfriend.com/refractometer-calculator/
http://onebeer.net/refractometer.shtml
http://seanterrill.com/2012/01/06/refractometer-calculator/

Most require a reading in °Brix.

For your brew you should have got a OG of 16 °Brix and and FG of 7.5 °Brix.

This works out to an OG of 1.065 and FG of 1.012 corrected. About 7.2%ABV.

 

[Danscraftbeer]

Just use the hydrometer for the FG. The Refractometer is good quick and easy way to test for every step in pre ferment stages.
I don't bother with the conversions etc.