Refractometers for measuring gravity

[JamesF]

As just mentioned in the current "measuring gravity" thread...

I already have a refractometer. I use it for measuring the sugar content of apple juice before fermentation and I'd probably be a bit more thorough as regards measuring my beer gravity if I could use it for that too because it's less "invasive". For measuring with a hydrometer I usually take a sample with a wine thief, but just being able to grab a couple of drops with a pipette or syringe definitely appeals.

Are there any dos and don'ts, top tips etc.?

James

[Hairybiker]

Jim had a thread on this earlier, try searching for it.
But I use my refractometer for OG testing, mine has a gravity scale making the conversion from brix easier.

[JamesF]

Ah, that's a good point. I think mine is brix-only. I'll have to check.

James

[JamesF]

Looks like it's an awkward calculation to do in one's head, but there are calculators on-line to go from Brix to SG and I have access to the interwebs from the beer shack. Allegedly the formula is:

SG = (Brix / (258.6-((Brix / 258.2)*227.1))) + 1

which I found on one site.

James

[JamesF]

Hmmm. Having hunted down a few past threads it seems things are rather more complicated than they appeared at first. I think a bit of work is going to be required.

James

[MTW]

They're great for checking sparge runnings and pre boil OG on brewday - close enough for me to know where I'm at, though I use a hydrometer for OG and FG after that. Once there's alcohol in there, you're into keeping logs of your own wort factors and making conversions: I have used the refractometer just to check whether things are still moving in the FV, but not for the 'final' FG.

[jmc]

Much easier, simpler to use and less wasted beer.
I have a chart printed off I use for the SG during the brew and FG calcs.
Easy once you get used to it and no maths involved

Chart available here: Topic: Refractometers - worth having?

[JamesF]

Yes, I think perhaps printing one out and laminating it for use in the beer shack has to be a plan. I've checked my refractometer this lunchtime and it is brix-only, from 0 to 32. I think that should be more than ample for my brewing

James

[Jocky]

0-32 Brix is ideal.

You will need to work out what the correction factor is for your refractometer to get from Brix to SG: http://www.brewersfriend.com/how-to-det ... on-factor/

[Aleman]

For mashing purposes I go with a simple multiply by 4 rule of thumb.

For the final OG reading I use a formula (beer smiths default), for FG reading I use Sean Terrills formula (Do a google Search) as it has a much better correlation with a good hydrometer reading than the usual curve fit formulae.

I do have a log of SG, FG (Hydrometer) and Starting, Ending Brix for all the beers I've made since getting a refractometer, which allows me to tailor any fudge factors pretty closely to Style and gravity.

[MTW]

Much easier, simpler to use and less wasted beer.
I have a chart printed off I use for the SG during the brew and FG calcs.
Easy once you get used to it and no maths involved

Chart available here: Topic: Refractometers - worth having?

Doesn't waste much beer using a hydrometer for FG: maybe 70ml, by which time I'm quite happy to taste it anyway. Once it's stopped moving on the refractometer for a few days, out comes the finishing hydrometer. Sorted.

I can't imagine not using a hydrometer for FG. I don't think HMRC would knowingly accept refractometer-based ABV calcs from a pro microbrewer, for what it's worth.

[Aleman]

I don't think HMRC would knowingly accept refractometer-based ABV calcs from a pro microbrewer

I do

I can't remember what the head brewer at Seren said exactly but it was along the lines of "As long as it is consistently reproducible, it does not matter what instrument is used for determining gravity"

[MTW]

I don't think HMRC would knowingly accept refractometer-based ABV calcs from a pro microbrewer

I do

I can't remember what the head brewer at Seren said exactly but it was along the lines of "As long as it is consistently reproducible, it does not matter what instrument is used for determining gravity"

Excellent. I will tell a pro brewer I know to give me his expensive hydrometers in return for my Chinese refractometer. Think of the beer he will save! Funny how they always take slightly longer to sink as the ABV approaches 7.5%