Trust the thermometer or hydrometer?

[Goggleeye]

I can guess what most of you are thinking-go with the hydrometer. I have three different hydrometers, all of which read the same. But when I go to density according to hydrometer, our syrup is so thick it will hardly filter and some of our customers even complain how thick it is. So we’ve bottled by temp now for several years. When we compare ours to commercial maple, it matches when we go by temp. The stuff we go by hydrometer is corn syrup thick. I know I’m getting the temps right when using the hydrometer. I’m a bit of a perfectionist when it comes to my syrup, and it bugs me scientifically that my thermometer and hydrometer readings don’t match. Any thoughts? Btw, when the hydrometer is on, the temp reads 222, and we are about 350 ft above sea level.

[OGDENS SUGAR BUSH]

temp should be 211f when you use the hydrometer

[bill m]

You say your 3 hydrometers all read the same but have they been checked to be sure they are calibrated correctly? Also 222 degrees sounds way to high.

[upsmapleman]

Sounds like you are using the cold line with hot syrup. Check your syrup when it is 60 degrees and see what it reads.

[Goggleeye]

The syrup is boiling at 222, I’m checking density once it cools to 211. And I’m using the hot line. I will give it a try at 60 with the next jar I open.
No, haven’t had the hydrometers checked. How would I do that?

[Russell Lampron]

You need both to be accurate but the hydrometer is what you trust. If you can't find someone near you to test your hydrometers buy a new Leader hydrometer. They are VT certified and there is a red line in the top of the glass that ends at the top line on the paper. If the paper slips from banging it off the bottom of the hydrometer cup you know right away. That 222* temperature is about 3* higher than syrup should be so it's still too heavy.

[Chickenman]

Sounds like your thermometer is out of calibration. I agree with having your hydrometer checked, but you say the 3 are agreeing with each other, I would trust them. Go with the hydro reading.

[buckeye gold]

I may be wrong on this and if I am someone please correct me. A simple way to check relative accuracy is to prepare a test solution. The simplest and most relative would be a sugar solution. Use distilled water or permeate and make a 66% sugar solution. I'll use a simple example:

bring 210 grams of distilled water to a boil remove from heat, it can cool slightly
Have 132 grams of sugar already weighed out and setting on a scale in a heat capable container (don't forget to tare off the container)
add the hot water until the scale reads 200 grams and mix until sugar is completely in solution.
Check weight after cooling and add water to bring to 200 again in case enough evaporated to change solution (it probably won't)
Then test your hydrometers at 60 with this solution, they should read 66 brix. I wouldn't be too concerned if they were slightly off (.1 -.2 brix) as this isn't a lab grade solution, but they should be really close. This should give you an idea if they are way off or not.

A known glycerin solution would be best, but this uses simple household items. You can use the syrup water for sweetener

[DrTimPerkins]

What are you using for a thermometer? Did the calibration screw get changed? What is the temperature of boiling water?

https://www.youtube.com/watch?v=Icn3Fgongjo

[maple flats]

I used to, after checking the boiling point of water that day, adjust the zero of the thermometer but at times the density seemed off a little. I then got a Marcland baro/boil temp meter. That helped a lot since by then I had an auto draw. I now check that meter every 2 hours or so, and reset the auto draw if needed. Before that I had only tested the boiling temp to start the day, but the barometric pressure changes often, and with every such change the boiling point of water changes. This might also be part of the issue. I now get very close, but I final check everything using one of my hydrometers. I now use a Smoky Lake Gold hydrometer, it is only better because it has a ref line to indicate if the paper has not moved. When you buy a hydrometer you can make such a mark in the box it came in for future reference. I just never did that in the past.

[Goggleeye]

Thanks for all the thoughts and suggestions. I definitely have some experimentation to do this weekend. I'm going to check my thermometers - I had been using digital, and two different ones agreed, so I assumed they were correct. Would it work to check my hydrometers against commercial syrup?

[Sugarmaker]

Googleeye,
What is commercial syrup?
I would say you should be making syrup off the evaporator at around 216/217 F.?
Your canning temps should be 180 F. If your going higher the syrup would be boiling and would need to be filtered again.
Maybe I am missing something?
Yes good to check your thermometer in boiling water too. They should be in tenths of a degree.
Let us know what you find out.
Regards,
Chris

[30AcreWoods]

A quick, temporary remedy is to put your thermometers in boiling water and see what they read. Add 7 degrees, and that will be really close to where you need to draw off on a given day. But as others have said, barometric pressure changes frequently, and a well calibrated hydrometer (temperature compensated) is the way to go. There are also phone apps that will give you the boiling temperature of water at your location (pressure compensated), so if you have an accurate thermometer, that can be a good crutch as well. Many ways to skin this cat...

[Michael Greer]

I use the hydrometer to set my temperature for the day, which can vary with changes in air pressure. I cook to just a tad below that temp all day and draw off into a big pot that goes onto the nearby gas stove. When that pot is nearly full, I boil to the exact hydrometer reading and filter and bottle. This has eliminated the crystals that we used to get in our syrup and has eliminated the too thick/too thin variations. Temperature can vary even in the course of a day if the weather changes, but the hydrometer tells the truth.

[bill m]

At our associations annual winter meeting we had a talk by Joel Boutin, agriculture technician and advisor to the CETAA in Quebec. To check a thermometer you need to boil a pot of water for 3 minutes before checking it. Anything less is considered just hot water, not boiling. The water must be at least 3 1/2 inches deep and the thermometer must be 1/4 inch off the bottom, it can not touch.

[Goggleeye]

Ok, got a chance to do some experimentation. Water from our house RO boiled at 212.0. Syrup sample I pulled from last year boiled at 219.7. Hydrometer read 60.3 brix@211.0. These reading all seem to be acceptable. So why could I have been getting such different readings in the canning kitchen? Operator error I suppose. But I sure thought I was being careful in the past about reading the hot line while it was at 211. How much can barometric pressure throw off the boiling point?
I’m beginning to wonder if going past density is the cause of the deposition I’m getting on the bottom inch of glass occasionally. It doesn’t seem to show up for a couple months, but when it gets warm in the summer there is a film that forms on the glass on the bottom inch or so of the jar. Does anybody else have that problem? I keep wondering if it is not the filter aid. After we get it to temperature or density in the finishing pan, we immediately filter through the Siro filter and then into the canning unit. Often times, it is above 190 when it goes into the canning unit, but we never reheat above 190. So it shouldn’t be more sand from heating it up again. I’ve looked at it under a microscope, and it doesn’t really look like filter aid, but I’m not sure. Any thoughts on that issue?

[Super Sapper]

Were you checking density with filter aid in the syrup? That could throw the reading off.

[Goggleeye]

Yes I sure was.

[Goggleeye]

Yes I sure was. I got to thinking about it more, and I think I was checking density before I put the filter aid in.

[Sugarmaker]

I had never thought about filter aid effecting the density? Very well could be? do a cold test on your finished syrup too. A good tool is the Murphy cup. Since you can check density at any temp.
Sounds like all the other things your doing fine.
Not sure what the stuff is in the bottom of the jars. First guess would be sugarsand but if your doing a good job filtering till clear, you should be ok there. the 190 during finish canning might be a touch hot especially if the thermometer is not reading. Might be going over 200 F in the canner causing some sugarsand to reform?? Thats just a guess.
Double check your filtering process. Have you changed filters on the Siro?
Syrup temp from filter to canner should not be a issue.
How is the season progressing in MO? we need some pictures!
Keep boiling!
Regards,
Chris

[DrTimPerkins]

Filter aid doesn't affect hydrometer readings unless there is a huge excess of it -- same as niter doesn't effect hydrometer readings. The hydrometer measures dissolved solids, not suspended solids. If you toss a lot of sugar into a tank, you'll change the hydrometer reading. Toss a lot of dirt in and you won't. Same thing....the dirt doesn't dissolve, so the hydrometer reading isn't affected.

I agree about the Murphy Cup being a useful tool. Bit of a learning curve (you've got to realize it is a thermometer, not a hydrometer), but once you get your head around it getting the density of syrup right is very easy.

Perhaps there are some helpful suggestions here https://www.youtube.com/playlist?list=PLZP4fDl-nB98B3TQ4YofaQQkRi-tC0ut9 Check the videos on density and on filtering

[woodguyrob]

A little gold mine of youtube vids in that link ...thanks Dr. Tim!

[amasonry]

it might be you need more covers or be faster. so you bring your syrup to density. but all the time filtering, canning, moving, bottling, the hot syrup is still evaporating. i had the same problem years ago. not all my bottled syrup was heavy mostly the last couple of gallons. just my two cents

[DougM]

There is a correction chart in the Maple Syrup Producers Manual. We use it quite often when our syrup is not at exact temperature. We have had three separate batches from our 2019 syrup tested independently, one was 66.8, one was 68.0 and one was 66.2 so we apparently goofed on that one.