Me too, not even absolutely sure where my refractometer is! But this thread leads me to a related question. I’ve noticed some people use a refractometer to determine when their mash has gone to completion. I rely on an iodine test. What am I missing?
You check gravity after mash rests to see how close you are getting to the target gravity. For instance, I use no-sparge and step mash, so I use Kai’s maximum first wort gravity prediction and refractometer readings to determine my conversion efficiency.
So since I sparge, no real advantage to my using a refractometer, right?
Iodine test will tell you when much, but not all, of the starches are converted to sugars. But results will vary and are not very reliable. On the other hand, measuring gravity or Brix over time will tell you if conversion is still going on. If more sugars are being produced, readings will continue to rise. Only when readings stay stable over the course of ~10 minutes is conversion really “done”. And even then, it might only be telling you about conversion of starches into sugars, but not whether those sugars are very fermentable! So even then, you might for certain styles want to mash even longer!
Ultimately, at a certain point, you need to make a decision and just stop mashing when you think it’s been “good enough”. For me, I mash for only 45 minutes usually, but am starting to mash longer for some styles. I don’t even measure pre-boil. I get good efficiency pretty consistently so I just keep on rocking. The whole thing is all optional, and decisions can be based on personal experience where appropriate, and we might not need to measure every dang thing like many of us tend to do. Even FG… does it really matter??? If the final beer tastes good, who cares about the FG!! Or the ABV!! Does it really matter??? It’s a decision we each need to make on our own.
Wrong. You can still calculate the maximum first wort gravity using Kai’s formulas and determine the efficiency of conversion. It just works out good when you no-sparge because the first wort gravity IS your preboil gravity.
It has nothing to do with a refractometer. I just happen to use a refractometer instead of a hydrometer.
I mash 60, just because, iodine test to make sure everything’s going as usual, mash off 10-20 and sparge. I get good yield (>33ppg in homebrew terms) and good attenuation (>78% ADF). I’ll stick with that. 
Whatever floats your boat. We are into knowing all the particulars of a batch so that we can improve and strengthen our spreadsheet so we get more in depth than most. Nothing wrong with doing what works.
I’ve found the iodine test unreliable, so I use conversion efficiency to make sure the mash is done.
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Calibrate with H2O every use. Already do that, check
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Compare hydrometer to refractometer several times with unfermented wort to confirm MY correction factor.
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Use the calculator with MY correction factor, or be crazy and skip step 2 and just use 1.04 lol
Thanks! I will do step 2 for a while and learn my correction factor. How many batches do you think? And could I do this by creating several various samples of sugar water?
Meanwhile I will use the calculator with 1.04 but compare my results to hydrometer FG and calculated ABV.
PS, sorry I started a fight
I would calculate the correction factor for your equipment and run with it. Especially for just checking pre-fermentation wort.
You may want to be a little more rigorous for measuring fermenting wort but even then, I’ve never found it necessary to recalculate the correction factor unless you see something amiss in your numbers.
I firmly believe in Dave’s assertion before that the correction factor specific to you is key in getting reliable numbers out of your unit.
Time was, I checked the mash with a refractometer at the same time as my iodine test. I quit because it was one more thing to do, and it was always exactly the same. I just looked at Kai’s table and guess what? There’s the number I was always hitting. So I guess I’ve sort of calibrated my system, and as long as I’m using similar malts and water/grain ratios, I probably don’t even need the iodine test (it’s always negative by 60 min anyway) but it’s a habit. If I ever decide to make radical changes, now I know how to dial it in again! Thanks all.
Excellent, man! The key is always to find what works for YOU!
Looks like I’m going to blind trust 1.04, because my smart phone doesn’t play well with excel
Don’t do it!
The Excel app doesn’t work for you?
Jim, what kind of phone? What’s it doing?
Nope. I downloaded it, and can see it, but it won’t even let me enter data.
So, what is the worst that can happen if I arbitrarily used the correction factor of 1.04?
It MAY skew your numbers. Then again, 1.04 might be your number.
Jim, if it says your file is read only, you just have to save a copy. You should be able to save changes to that copy. (I save each recipe I do in Bru’n Water with the recipe in th e file name.) Otherwise it’s just a matter of getting your finger on those tiny little fields!
Just playing around with my refractometer app, using 20° OG and 10° FG I get the following ABVs by changing the correction factor to…
1.08 7.2%
1.04 7.5%
1.00 7.8%
.98 7.8%
Frankly that’s totally close enough for me! My main use of FG readings is to verify Terminal Gravity. When people ask me what the ABV of my beers is, I usually ask “what does it seem like?” Their perception is more valuable to me than what it actually is. Then I’ll tell them a rounded off figure, like if it’s calculated to 7.35% I’ll say “it’s about 7%”.
Will using an arbitrary correction factor cause my refractometer final gravity readings to bounce around, so long as I use the same factor?
The end of civilization as we know it! ;D