Boiling point question

[Rangdale]

Got started making syrup a few years ago (wow, is it ever addicting) just as a hobby for me and my girls. For the first couple of years I just used a thermometer and brought it up to 220 which is 7.5 degrees above boiling on my stove. Afer finding this site last year and all the recommendations about hydrometers, I went out and got one. Wow, what a difference!! Turned out we had basically been making slightly thick (although still really good tasting) maple water. My question is this, I had to get the syrup up to 224.5 degrees on my thermometer before the hydrometer said it was syrup. Is the 7.5 degree above boiling water just a ballpark number? I thought perhaps I had a faulty hydrometer so I tested a bottle of syrup from LL Bean and it was spot on. I clearly will be using a hyrdrometer from here on out, was just curious if anyone had any info on the old 7.5 degree rule. Thanks!

[unc23win]

7.5 over boiling water is a ball park. Hydrometers are way more accurate. Baromtric pressure will change the boiling temperature. Most people use the thermometer and then check it with the hydrometer.

[jrgagne99]

Make sure you follow the instuctions on your hydrometer usage too. The instructions are very important to getting an accurate reading!

[BreezyHill]

Our setup works best on batch draw off. So I have a thermometer that lets me know when it is close. I check with hyro at start and watch temp during draw. When temp drops below where the hydro said it was good we close valve and check the batch one more time. By law you are looking for 11#/gallon. The hydro can tell you this and a thermo tells temp. The temp is dependent on many factors like: barometric pressure that day, accuracy of the thermo, proximity of the thermo stem to the pan floor, etc. I saw one guy with the stem of the thermo touching the pan and he always made fancy. He hated hdros because they broke. In reality he was dropping it into the test container thinking it was syrup and it was just colored water...so it hit the bottom and shattered. My dad pointed out the issue and he was surprised how long it took to make real syrup after that.
Don't worry you are not the only one that has had the issue.

Ben

[bowhunter]

Temperature measurement is a little tricky sometimes so you have to use the hydrometer as the last word. I worked as an engineer and manager in the chemical processing industry and we typically saw significant (3-4 degrees F) discrepancy in temperature measurements using very sophisticated equipment.

[Clarkfield Farms]

And back before they had thermometers to use, they'd boil 'til it came off a spatula or paddle in a sheet or ribbon pattern, not just dripping. Not as sophisticated, but it worked for them. Still does. :)

Caveat: No, I don't use that method and am not recommending it either, just sayin'. Plus, they didn't have Big Brother and his regulations to contend with, and they were generally only making it for their own use. That's probably how they figured out that if it goes moldy, just re-boil and skim off the crud. :(

I'm thankful for what we've got today; I say use the thermometer to draw-off, then the hydrometer for finishing - pretty sure most do it that way anyhow.

[madmapler]

C'mon now...L L Bean syrup???:)

[maple flats]

To really get an accurate measurement you need a very accurate thermometer AND need to know the boiling point of water at that moment. It is far better to use a hydrometer. Then you need to test at the hot or cold temps shown on the hydrometer, or you need a chart to get the exact reading. The density reading changes quickly with temperature. For example, the hot line is for 211 F. To get that you are supposed to draw boiling syrup into the cup, dump it back into the evaporator and immediately draw again, then carefully lower the hydrometer into the test cup and get a reading. By that time it will supposedly be 211 F. It is better to get an accu-cup which has the thermometer built in. Then put the syrup (?) in the cup and get a hydrometer and temp reading. Then refer to the chart. This is the easiest way to be sure. However you can do it without the accu-cup. You do need an accurate thermometer and the hydrometer. Then the formula to verify the density is found in the North American Maple Syrup Producer's Manual, The maple maker's bible and encyclopedia.

[delivron]

Keep in mind that both thermometers and hydrometers can go off calibration. Carefully float your hydrometer in the cup don't let it bounce on the bottom. You can get a micro crack in the bottom. Also the hydrometer calibrations are known to come lose and move down the tube. Maple syrup is generally syrup when the sap reaches 7.1 degrees above the boiling point of water a sea level. Almost no one has a sugar house at or close to sea level. As a result the boiling point changes as the elevation and air pressure changes. Standard pressure at sea level: 29.92 in. (760 mm) high, or 1013 millibars At 1000 feet the boiling point is 210.1 at 2000 feet the boiling point is 208.1.

[Rangdale]

Yup, LL Bean syrup! It's just down the road a bit and the little bottle make great stocking stuffers!

[Ravenseye]

What about a refractometer for checking on the syrup?