Thermometers - How to check your calibration at Mash temp

Post #1 made 4 years ago
I've had lots of time to think about all things beer lately as I recover from a bout of "Man Flu"

Anyway one thing that came to me as I was coughing up half a lung one afternoon was about Calibrating Thermometers. There's been lots written on here by PistolPatch about not trusting one single thermometer, even if its tested correct with Freezing Water and Boiling water at 0'C and 100'c (32 F and 212 F for our US friends) it doesnt mean that it's right at our most important temp which is Mash temp or around 66 C (150.8F) Variances of several degrees at mash temp are not uncommon. So the problem then is what one do we trust? I think I might have an answer.

It got me thinking what can we use (easily and cheaply) to test at those temperatures. We know Water boils at 100 degrees so what products can we get that boil at or around Mash temps?

I did a bit of research and there's 2 products we can all get hold of relatively easily that will allow us to test our Thermometers at or around Mash temps.

Methanol and Ethanol

Ethanol is fairly common these days as many internal (Fancy) heaters use Ethanol as a fuel source. Here in Australia you can buy it from your Local Hardware in 1L containers.

Methanol is a little harder to come by (Here in Oz anyway) But you can pick it up from Hobby Shops again in 1L containers. It's often used for Model Cars and Planes. On a bigger scale it's often used on the Car racing scene if you want access to 200L drums of it!

Now both these products are flammable and they are both Alcohol based. (Not designed to drink so don't get ideas) So being Flammable they must be handled appropriately.

Anyway the main thing of interest to us HomeBrewers is their Boiling points.

Methanol has a boiling point of 66' Celsius (150.8F) which is just about as perfect as you can get for checking your Mash temp accuracy.

Ethanol has a slightly higher boiling point of 78' Celsius so whilst not perfect is a lot closer than boiling water, and also works well for a Mash out temp check.

So if we were to carefully bring either of these to products to the boil (insert warnings - Carefully, with no naked flames, in a well ventilated area etc etc) We can then test the temperature of our thermometers at the most important Temp to us.

So as long as you aren't Stupid :headhit: it's an inexpensive and quick way to check your thermometer accuracy, using a product readily available and costing only a few $$. Once you have tested, let the Methanol Cool, tip it back in its container and put away until you want to test again.

NB: I expect elevation above Sea level may influence the exact boiling point (as it does with water) and the above Boiling point Temps are quoted at Sea level. So for those living in Mountains you may need to adjust slighlty. For us here in Australia the country as pretty much flat so is rarely a problem :lol:

I'll say it again just to cover my butt, if you have a tendency to always cut yourself shaving, trip over things, hit your thumb with a hammer, fall asleep with Cigarettes in your mouth then maybe this method is not for you. :lol: Both these products WILL ignite near open flames. So for those with Gas Cooktops it's a definite No No.
Last edited by bundy on 07 Jun 2014, 14:47, edited 1 time in total.
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Post #2 made 4 years ago
You are the man bundy!

I remember looking for some solution like that and couldn't find anything. Nice job mate :thumbs:.

On the safety side of things, maybe what anyone could do, gas or electric, is heat a large saucepan with water to a bit over 66C or whatever, turn the heat off and then put some of the ethanol/methanol in a stainless steel bowl. Hopefully it will start boiling. Check the temp when it starts to go off the boil. You get the idea ;).

Top stuff bundy :salute:.
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Post #3 made 4 years ago
Re safety, the boiling part isn't so much the issue, as ethanol/ methanol is boiled off all the time in distilleries. Even humble home ones. The potential problem is igniting the methanol or ethanol vapour once it does start to boil as when in a gaseous state it is much more volatile than when in liquid form. So NO naked flames is a must, and no sticking your head over the pot with a ciggy hanging out.

Once the gas disperses to atmosphere though it's fine.
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Post #5 made 4 years ago
Has anybody been crazy enough to try this yet?

Just curious.
I spent lots of money on booze, birds and fast cars. The rest I squandered
I've stopped drinking, but only when I'm asleep
I ONCE gave up women and alcohol - it was the worst 20 minutes of my life
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Post #6 made 4 years ago
Mally, I learned never to boil Methanol, the Gas Fumes is Very Poisoning if you ever breath it!!

Since, Some of use boil off the Ethanol from a BAD batch of beer, the Fumes Are Wonderful(Hic).

Also 174F is a good Number to set/differ to when use that thermometer when Mashing.
Honest Officer, I swear to Drunk, I am Not God.
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