Recently got myself an iSpindel. I know the intention is generally to be able to keep an eye on gravity during fermentation, but can you also use them for checking gravity post-mash? I'd prefer using it over the hydrometer. Only issue is whether it would work as well in hot wort, but also if it would be able to withstand those temperatures?
Using iSpindel for post mash gravity
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Agentgonzo
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I would doubt it. I think it's made of PET. The tubes are made from the stuff they make plastic bottles from. It's a thermoplastic and it softens seen heated so it can be inflated inside a mold to form the bottle. So personally I wouldn't trust it with the 65 degrees of a mash.
I have a refractometer that works well for post mash gravity readings
I have a refractometer that works well for post mash gravity readings
Cheshire Cat
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Why do you need to measure post mash SG? A genuine question as I’ve never done it.
I check mine using a refractometer post-sparging so I know whether I may need to boil for a bit longer to hit my target OG.
To measure efficiency of the mash. I do BIAB, and don't sparge. So post-mash is also pre-boil for me.
peebee
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I think I can tell from the language you use ("post-mash", "pre-boil", etc.) you are using "Beersmith" brewing software? (If not Beersmith, something much like it). Brad Smith (Beersmith), or maybe it's one of his competitors, have a lot to answer for with this stuff! You don't need to know "post-mash" or "pre-boil" gravities (as @Cheshire Cat alludes to), you especially don't want to dip an expensive delicate instrument into hot wort to get it! A refractometer is more than adequately accurate and robust enough for the job, fragile glass and plastic devices (like hydrometers) are not!
The information you gain from recording this information is useful for tracking down inefficiencies in your methods, so you get a clue how to correct them in future. They don't help current inefficiencies 'cos it's too late! As far as I can tell, "post-mash" is taken after mash run-off and sparge (so you have the "pre-boil" quantity) and "pre-boil" is after adding sugar (etc.). That way "pre-boil" and "post-mash" need not be the same, BIAB or no.
If you feel you must collect the information, get a cheap refractometer. DON'T put your expensive kit into hot wort!
Have I said it enough times? Just to be sure ... DON'T put your expensive hydrometer kit into hot wort!
The information you gain from recording this information is useful for tracking down inefficiencies in your methods, so you get a clue how to correct them in future. They don't help current inefficiencies 'cos it's too late! As far as I can tell, "post-mash" is taken after mash run-off and sparge (so you have the "pre-boil" quantity) and "pre-boil" is after adding sugar (etc.). That way "pre-boil" and "post-mash" need not be the same, BIAB or no.
If you feel you must collect the information, get a cheap refractometer. DON'T put your expensive kit into hot wort!
Have I said it enough times? Just to be sure ... DON'T put your expensive hydrometer kit into hot wort!
This is exactly it. Not every brew will be the same. And I like to compare my efficiencies with what I did different in the brew to work out the best way. In BIAB, efficiency is especially important, as it's not as easy to achieve as high efficiencies as you do the traditional method.
Hmm, I bought a cheap refractometer for exactly this but what a waste of money. There are probably better cheap ones than the one I got but mine is total ****. It gives a different reading every time and I don’t mean just a point or two out. I suppose there also a chance I’m using it wrong but if you just drop some wort on the glass to cover it and close the lid then look through the eye piece then it is ****.
Agentgonzo
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If you get different readings from successive attempts, then it's not likely to be a problem with the refractometer, because it has no moving parts and is just adhering to the laws is physics. Mine did the same until I had used it a few times and learnt more about it.
Take a few readings and either average them out or take the latter ones. I found mine stabilised after the first 2 readings. Not sure why. It could be that I didn't clean it properly before use and that contaminated the sample or there was residual water/sugar in the dropper, it could be that there was residual water on the refractometer that threw off the first reading. It could be that the warm/hot wort had water evaporate off and was therefore more concentrated than the actual wort, and got more concentrated over time. There are many things that go on.
I've found I get stable readings if I put more wort on it or rinse it in wort before the first reading, rather than using a couple of drops.
Mine is a cheap one, and the readings are off, but they are off consistently (by 10%) so it's dead easy to compensate.
I use a refractometer and hydrometer just to get two readings. They're usually very close or completely the same. I have a cheapo one as well, £15 I think it cost.
Ok, I’ll have a play with it then. I’d really like to know my post boil gravities. Does the temperature of the wort make a difference to the accuracy of the readings?
I'm current mid-brew day and just took a reading. 1.052 on both hydrometer and refractometer, at about 52C (adjusted the hydrometer reading to 20C). So I don't think so.
peebee
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It was probably when I started with this "post-mash/pre-boil" palaver I noticed that with a refractometer too. I reckon it's one of the "advantages" of a refractometer making itself known as a "disadvantage"! You only need a couple of drops, but at this stage the wort is lots of mingling liquids at different gravities, and "two drops" of that is a bit of a lottery.
I always ensure the wort is well stirred before sampling. (And we probably all use "cheap" refractometers anyway!).
Cheshire Cat
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Do you guys change the process or add anything based on the mash SG? For example boil time, or add sugar or water to increase/decrease the OG?
peebee
Out of Control
Put some wort aside, cool it, and measure that.
Yes, temperature will make a difference! More so with a hydrometer measuring "SG" (and this time I don't mean because it shattered due to the sharp change of temperature). The SG temperature correction tables are all well and good, but a bit dodgy all the same: They take a measurement that has an inbuilt temperature correction (SG), undoes the temperature correction bit (I bet you didn't know "SG" had one!), then reapplies the correction "calculated" for a different temperature. And if that sounds dodgy ... it is!
Ive just grabbed my refractometer to see if I could calibrate it although I did it when I first got it with tap water setting it to 1.000. As it happens, I still have the sample of the Lager I made yesterday sitting in a trail jar at 20 degrees. The hydrometer says it’s 1.050 but a few drops of this in my refractometer is showing it as 1.045! I’ve adjusted the refactometer to show this sample as 1.050 and now water is reading 1.005
Ive just grabbed my refractometer to see if I could calibrate it although I did it when I first got it with tap water setting it to 1.000. As it happens, I still have the sample of the Lager I made yesterday sitting in a trail jar at 20 degrees. The hydrometer says it’s 1.050 but a few drops of this in my refractometer is showing it as 1.045! I’ve adjusted the refactometer to show this sample as 1.050 and now water is reading 1.005
You ideally need to calibrate a refractometer with distilled water, but I wouldn't expect tap water to be the that far out. If I feel suitably inquisitive later on I'll do a back-to-back with mine and see what it says.
Agentgonzo
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So a few things here.Ive just grabbed my refractometer to see if I could calibrate it although I did it when I first got it with tap water setting it to 1.000. As it happens, I still have the sample of the Lager I made yesterday sitting in a trail jar at 20 degrees. The hydrometer says it’s 1.050 but a few drops of this in my refractometer is showing it as 1.045! I’ve adjusted the refactometer to show this sample as 1.050 and now water is reading 1.005
1. You only calibrate a refractometer to be 1.000 with pure water, and you've just found out why you can't calibrate it with a wort of a known gravity.
2. Wort and sucrose/fructose solution have different indexes of refraction for the same gravity. Refractometers are generally designed for wine making (fructose) and so you need to apply a "wort correction factor" (normally 1.04). Google it and you'll find lots of explanation.
3. Yours sounds exactly like mine with it being consistently off by 10%. I add 10% to the reading on mine, which would take your 1.0 45 up to 1.049, which is within experimental error of 1.050.
Agentgonzo
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I did both distilled water (from the tumble dryer condenser) and tap water. Both read 1.000
peebee
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Hopefully, the topic of this thread is dealt with, and it wandering off subject is of no consequence?
The subject of "temperature" and popping expensive bits of kit into hot liquid has presumably been dissuaded? Now temperature and hydrometers. First, what is it we are trying to measure ... "Specific Gravity" or "S.G." or "Relative Density": I'll get a small jam-jar. It weighs 107.79g. Filled with tap water it weighs 211.11g. The water it contains weighs 103.32g. That's 3.644oz; I switch from grams so the "S.G." (which is a ratio and has no units) won't get confused with the similar looking g/ml which density is measured in. This is for real! But a jam-jar isn't a scientific instrument, so the rest is calculated (this is for illustrative purposes).
The jam-jar is emptied, filled with wort, and weighed again. The water has been sitting about in the same room as the wort so is the same temperature. The sample of wort weighs 3.779oz.
So: 3.779 / 3.644 = 1.037
The wort has a specific gravity of 1.037. At a temperature of ... who cares! It won't be making enough difference to register.
And water: Just divide the first result with itself ... 3.644 / 3.644 ... which is of course ONE! At a temperature of ... you've guessed it; "who cares"!
Now it just so happens we can get a device called a "hydrometer" that can be calibrated to measure S.G. Because we don't want to measure water that's been hanging around the same room as the wort, nor do we want to do the complicated division, so we'll assume the water has been measured at 20°C (it's a fixed "constant" at a set temperature) and the wort sample is also at 20°C. If the wort isn't at 20°C, we'll need a table to adjust the reading, and also take into account the 20°C water reference: Complicated! Lucky we've got tables.
The tables are derived from "empirical" data (the result of experiment) not mathematical formula. Any mathematical formula used by computer calculators will generally also be based on empirical data (immensely complicated "polynomials").
Now it just so happens we also can get another device called a refractometer. It can also be adapted to read S.G. But it's not only temperature that needs accounting for, but there's also the composition of different substances in the water ... and that includes the different sugars (like sucrose, maltose, malt-dextrins, etc., etc.), oh aye, and chuck some alcohol in too? Now that is complicated!
I'd be sorry for the condescending tone, except I'm not! I got fed up with having been marginalised for not using a hydrometer and will get my own back having realised I was right all along.
The subject of "temperature" and popping expensive bits of kit into hot liquid has presumably been dissuaded? Now temperature and hydrometers. First, what is it we are trying to measure ... "Specific Gravity" or "S.G." or "Relative Density": I'll get a small jam-jar. It weighs 107.79g. Filled with tap water it weighs 211.11g. The water it contains weighs 103.32g. That's 3.644oz; I switch from grams so the "S.G." (which is a ratio and has no units) won't get confused with the similar looking g/ml which density is measured in. This is for real! But a jam-jar isn't a scientific instrument, so the rest is calculated (this is for illustrative purposes).
The jam-jar is emptied, filled with wort, and weighed again. The water has been sitting about in the same room as the wort so is the same temperature. The sample of wort weighs 3.779oz.
So: 3.779 / 3.644 = 1.037
The wort has a specific gravity of 1.037. At a temperature of ... who cares! It won't be making enough difference to register.
And water: Just divide the first result with itself ... 3.644 / 3.644 ... which is of course ONE! At a temperature of ... you've guessed it; "who cares"!
Now it just so happens we can get a device called a "hydrometer" that can be calibrated to measure S.G. Because we don't want to measure water that's been hanging around the same room as the wort, nor do we want to do the complicated division, so we'll assume the water has been measured at 20°C (it's a fixed "constant" at a set temperature) and the wort sample is also at 20°C. If the wort isn't at 20°C, we'll need a table to adjust the reading, and also take into account the 20°C water reference: Complicated! Lucky we've got tables.
The tables are derived from "empirical" data (the result of experiment) not mathematical formula. Any mathematical formula used by computer calculators will generally also be based on empirical data (immensely complicated "polynomials").
Now it just so happens we also can get another device called a refractometer. It can also be adapted to read S.G. But it's not only temperature that needs accounting for, but there's also the composition of different substances in the water ... and that includes the different sugars (like sucrose, maltose, malt-dextrins, etc., etc.), oh aye, and chuck some alcohol in too? Now that is complicated!
I'd be sorry for the condescending tone, except I'm not! I got fed up with having been marginalised for not using a hydrometer and will get my own back having realised I was right all along.
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