Refractometer--for filtered syrup only?

[maple marc]

Can a digital refractometer be used on any syrup--filtered or unfiltered? Or does it only work with filtered syrup?

Thanks

[maple marc]

Someone must know the answer to this question!

Thanks,
Marc

[emo]

You should be able to use it on any syrup, filtered or not filtered. I use an non-digital one to check sap and syrup through all stages; the refractometer goes 0-90%, through 3 separate scales.

[TheMapleMoose]

I use ours for unfiltered syrup once in a while. Seems to be a little inaccurate but I think it's because of the temperature....even though it's ATC. It's a lot more accurate on filtered, cooled syrup....I'm an expert by no means. This is just my experience.

[Snowy Pass Maple]

We have the Hanna refractometer rated for 0-85 - in my experience, it's very slow to stabilize on readings with syrup - unfiltered or filtered - even after the automatic temperature correction ends, it can change for 10-15 minutes. With a hot sample, it's essentially useless because you can have a lot of evaporation in that time.

Net is that I don't find it at all useful for syrup. (same issue with honey as well)

HOWEVER - I could not live without this for our RO! It is awesome for monitoring sap in tanks, feed to the evaporator, checking sugar in the woods, etc. Those measurements converge immediately and are very repeatable. It's rugged enough to carry around, dribble stuff all over the case and just rinse off. So I wouldn't hesitate to recommend it for those applications.

[johnallin]

Hey that's a good question...

It would make sense that the syrup should be clear (filtered?) to get an accurate reading, but since there are different methods of filtering - with some better than others, press vs. felt cone - I don't know how it can be accurate unless the sample is crystal clear.

Because a refractometer measures the speed it takes light to travel through the sample, I would think any cloudiness would slow the light moving through the sample and therefore the accuracy of the reading.
I know my Misco refractometer is sensitive to even small bubbles in the sample - they will throw the reading off. As for hot syrup, given a minute or so to equalize sample temp with the meter, it will compensate for temperature and give a good reading.

But from what I can see, there is no reference to using only filtered syrup. Maybe sucrose is denser than niter? and that's all it's testing for..

[maple marc]

Now that I have experience with a refractometer, let me answer my own question.

I bought the Milwaukee, and in my experience with unfiltered syrup, the results it returns are somewhat inconsistent. The cleaner the syrup, the better the results will be. I was hoping to use it on unfiltered syrup when I adjust the density before filtering and bottling. I have found that the longer the syrup settles, the more accurate the refractometer will be. On syrup with more sediment, the readings start high and slowly drop over the course of several minutes. Final results are uneven. I learned this by being as careful as possible about testing samples over and over. It seems to do a very good job on filtered syrup and sap.

I am not sure I will keep the unit. From John's post above, and from learning about the unit's technology, I believe that the expensive Misco unit may not do any better job with unfiltered syrup. The advantage of the Misco unit over Milwaukee appears to be its pocket size, portability, and ruggedness. That's probably what you get for an extra $300. The Misco unit also has a wider temperature range.

Old adage to remember: "If you have only one thermometer, you know exactly what the temperature is. If you have two thermometers, you're never really sure." Adding to this adage, same holds true if you take more than one reading of anything.

Marc

[Yellzee]

I have the Milwaulkee this year as well and find it too inconsistent to use for final bottling. It has been handy to give my father in law so when he is boiling down the turkey pot to get close to finish he can actually get reasonably close... in the past he just shut it down when it foamed up.

I am disappointed with it overall because I can't seem to trust it for the final ready for bottling test on hot syrup that is unfiltered. (not the units fault IMO)

[johnallin]

I think you'll find the Misco to be a reliable and handy tool for final density readings just before bottling; or for testing sap coming into the sugar house for that matter. But I don't think you should be using it for unfiltered syrup right off the evaporator, use a hydrometer instead. A hydrometer is going to give you a very accurate reading for hot syrup. I use an AccuCup with the hydrometer to test the density in my draw off pail and adjust accordingly if needed.
While I can get within a point or so, off the evap, there's too much going on to fiddle around for long. I find the Misco really shines when you want to test what's in the bottler, as a last check just before bottling, as you only need a drop from the spigot and not an entire hydro cup's worth.

[NTBugtraq]

I mistakenly created a thread on this topic (sorta) earlier today. More to the point, Post #4 in Thread: Hydrotherm broke, anyone use an Atago PAL-α? (http://mapletrader.com/community/showthread.php?23434-Hydrotherm-broke-anyone-use-an-Atago-PAL-α) describes a conversation I had today with an Atago representative. I specifically asked whether niter would interfere with accurate measurements on their Atago PAL-α (PAL alpha) model. She assured me it wouldn't, with some minor caveats (see the post).

Dr. Tim, in another thread on this subject titled eMaple digital refractometer (http://mapletrader.com/community/showthread.php?12474-eMaple-digital-refractometer) (Post #6), said that the quality of the materials used to make the refractometer make a difference too...suggesting the prism be made out of sapphire. I asked Atago, and theirs is made out of Optical Glass. Not sure how much worse optical glass is than sapphire?? I've got one coming here tomorrow anyway and will report back once I've given it a try.

FWIW, I am only concerned with the unit giving me the same measurement when I draw off the arch (e.g. no filtering) versus once its filtered.

Cheers,
Russ

[I Luv Stainless]

I use a refractometer as my primary draw-off testing tool in my 500 tap operation. Once you get it warmed up, it’s fast and it allows me to easily test different parts of my syrup pan for sugar content. I treat it as a ‘ballpark tool’ that is accurate to within a degree or so which is fine for draw-off for me. Once my syrup is off the evaporator and in my 5 gallon SS draw-off pot I will test with a hydrometer and refractometer to tweak sugar content before going to the filter press. This usually means adding some thinner sap from the syrup pan to reduce the sugar content to around 67 brix.

When you are using a hydrometer and refractometer together like this, your confidence in the accuracy of your refractometer readings improves.

[NTBugtraq]

I think you'll find the Misco to be a reliable and handy tool for final density readings just before bottling; or for testing sap coming into the sugar house for that matter. But I don't think you should be using it for unfiltered syrup right off the evaporator, use a hydrometer instead. A hydrometer is going to give you a very accurate reading for hot syrup.

John, what makes you feel the digital refractometer isn't as accurate with hot unfiltered syrup off the evap? I found using my hydrotherm to be a lot of work with the hot syrup (messy, hard to hold, sap all over the cup...) whereas a small spoon got me a sample from right in front of the spigot easily for the digital refractometer. I'm doing a series of tests (at the last point in the flue pan, then the 2nd channel syrup pan, then the spigot) which gets the tester good and warmed up for the final, most accurate test. I simply wipe the sample off with a damp cloth, then wipe with a tissue, next sample...nice and easy.

I discovered that my previous syrup producing efforts (based solely on a thermometer) have been hilariously random. Last year's syrup was 60.5 brix, and this years 70.5 brix. This after using a kettle to calibrate my thermometers...;-]

Cheers,
Russ

Cheers,
Russ

[johnallin]

John, what makes you feel the digital refractometer isn't as accurate with hot unfiltered syrup off the evap?

Russ, I'm still not sure if it makes a difference if the syrup is filtered or not, but what I've found with the Misco is that at higher temps it can take several readings before it settles down. It will start out with a high reading (71) and subsequently drop as much as a point each time until it's happy(?). This can take - for me anyway - up to two or three minutes... With the hydrometer; I can fill the cup, place the hydro' in, have a consistant reading right away and either keep drawing or stop when it gets below the red line.

Another quirk with the Misco (and maybe others?) is that at the higher setting of "Syrup>86°" it only reads in full numbers. At the lower setting "Syrup<86°" it reads out to tenths and is much quicker to settle in to a consistant reading. If your pulling hot syrup it can take a long time before it cools down to 86. I use it just before I go to my canner for re-heating, to do a final check. By that time my syrup at that time has cooled off somewhat and I am able to get readings that fall in the lower temp range and, again for me, seem to be more accurate.
Your method sounds like a great way to check density across the pan, and certainly better than relying on a temperature reading only, and if it's working for you - don't change a thing.

[NTBugtraq]

Please don't think my way is better...but I sure don't want to filter stuff that isn't right...I'm ok filtering stuff that's high, so if I'm only out a degree I can see putting the effort into filtering it. Luckily, I like syrup that's above 67, so, if it says 68 or above I can trust the digi has served me well.

Cheers,
Russ

[Snowy Pass Maple]

Dr. Tim, in another thread on this subject titled eMaple digital refractometer (http://mapletrader.com/community/showthread.php?12474-eMaple-digital-refractometer) (Post #6), said that the quality of the materials used to make the refractometer make a difference too...suggesting the prism be made out of sapphire. I asked Atago, and theirs is made out of Optical Glass. Not sure how much worse optical glass is than sapphire?? I've got one coming here tomorrow anyway and will report back once I've given it a try.


I'd guess that statement is for the durability of sapphire - it would be a lot harder to scratch up than anything else you could use. If you're putting unfiltered syrup samples on it with various mineral precipitates, could be a concern - but as long as you're careful to rinse it before wiping it, I'm sure you'll be fine.

[johnallin]

I do know from using the Misco that cleaning the lens thoroughly, before each sample, is critical. It may well be that sapphire is more resistant to scratching that optical glass and therefore a better long term investment. I'm pretty old school when it comes to "you get what you pay for". I think it applies here.

[NTBugtraq]

Well, finally able to post some observations of my Atago digital refractometer. I have only done 2 draw-offs with it, and my only method of comparing its accuracy is to use temperature. I drew off into my finishing pan, which then gets finished on a propane burner. My thermos are the +x over boiling point type, and were calibrated shortly before use in an electric kettle of water beside the finishing pan.

I found that all measurements rose after sitting longer. I measured at +5F and was getting 58.8-60.2 brix, at +7F got 65.8 brix, which then settled at 67 brix. The last sample sat for at least 30 minutes (over which time it went from 65.8 to 67 brix). I did a final check using a cooled bottle I had filled with that syrup, and it to measured 67 brix.

So, I'm satisfied. I get that the syrup continues to cook after I've turned the burner off, and I'm happy with 67 brix (its my preferred number). I'm pleased that the +7 came out at 65.8 brix initially...but it also shows just how much continues to evaporate if its not cooled quickly.

Cheers,
Russ

[NTBugtraq]

So I drew off my first syrup yesterday, and quickly tested it on my Atago Pal Alpha. The first reading wash 63.5 brix. I pulled it cause my thermos said it was at +8F. I only did the one test, as the amount was not enough for me to want to take to filter.

So, today I boiled till I got to +8F, figured I needed higher brix to add to what I drew yesterday. When I cracked the draw off valve, I let a few drops into my Atago. First readimg. @ 22.5C, 63.0 brix. I kept the valve cracked, and pressed the test button again 15 seconds later...64.5 brix, I did this over and over until at 16C it capped at 74.3 brix, after that, as the temp went down, the brix went down also...same sample.

So, clearly, what I need to figure out is what number the Atago gives at high temp that turns out to be 68 brix at 16C.