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Has anyone used this method this year and if so what were the results. Just looking for feedback. Thanks
I think I'm going to try it earlyish in the spring. Once we get reliable flying weather and they've brooded up a bit more. Too cold for that until probably 3rd week of March to 1st week of April usually.
 

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Old thread revive I know, but hoping to attract the help of a chemistry buff who could help.

Background to my question is that over here in New Zealand, treating for varroa mites by hanging OA impregnated cardboard strips between frames has become quite popular. It is very successful at killing mites, the jury is still out about possible damage to brood and bees, results on that can be mixed.

There is a guy selling the strips commercially, and a bunch of people making assorted home recipes. This has all been going reasonably well until a few weeks ago when the commercial guy took out a patent, which has restricted what "home brewers" such as myself can do.

That's the background, now the question. - The latest batch I have made has been using a cardboard I have not used before. A couple of days after making this batch, it started getting a formic acid smell. I am wondering if this means the cardboard is somehow reacting with the OA and converting it to FA? Any knowledgeable chemistry people could provide insight?

Have shown a pic below of some strips installed in a hive this morning.

 

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Hi OT, from what I gathered when I played with this stuff some years ago you have to be carefull when dissolving the OA into the hot glycerin cause if the temperature of the mixture exeeds 140 degrees the OA in the mixture can start to form formic acid. I also found that when mixing the OA into the glycerin there was a reaction which increased the temperature of the mixture which would mean you need to really control the temperature. I wonder what this guy is trying to patent as the story about this mixture being used with cardboard strips has already been public knowledge for about 3 years emanating from some Argentinian beekeepers, I think if you did a search on B L archives you could find the original posting. I am not too sure on the max temp it could be 140 degrees F or around 60 degrees C
 

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I have seen it suggested to heat just the glycerine to slightly over 200F. ~ 100C. then dump in the OA. That way the OA spends less time at the elevated temperature that causes the formic acid production. One might experiment with then adding a bit of high purity alcohol to aid dissolving and which will evaporate as the towels or cardboard cools and drys. I did prepare a batch of towels and stored some in a zip lock bag and they did smell a bit acidy after a while. Whether that would have had any negative effect on bees or not, I dont know.

I have been following the events on the forum that Oldtimer mentions; there have been lots of positive reports but a few mysterious troublesome incidents that have not been solved. Would be nice to have them out of the way before going whole hog. Perhaps temperature control during mixing is an issue. I am sure Oldtimer will be devoting his analytic powers to that!

I put some towels and cardboard strips in four hives last summer. Common corrugated cardboard separates and not suitable. I now have on hand some of the dense card stock about 70 thou. thick which is similar to the material used in the Argentinian patented strip, Aluen Cap. I will play around with it a bit in the spring.

Some claim they will knock down high mite loads but my personal take is that they are very good at maintaining LOW mite numbers. My experience is not worth much generally because I am quite isolated and am starting with very low counts. I also did several rounds of OA vapor so the net result was near zero mites when I put the bees to bed for the winter. Five of five are still alive as of yesterday.

My main point to be on the lookout for is negative effects.
 

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OT I was asked to post this from a very Knowledgable beekeeper who for some obscure reason cannot post it himself,
Oxalic acid dissolved in glycerin is well known to rapidly form a mono ester with the glycerin. This mono ester is very easy to decarboxylate (remove one of the acid groups as carbon dioxide) which leaves behind the glycerin ester of formic acid. Any water in the system will then hydrolyze this ester to form glycerin plus formic acid. All of these reactions can take place at room temperature, but at that temp they are slow. However, at temps above roughly 60 deg C the esterification reaction becomes pretty fast and by temps of 100 deg C the decarboxylation reaction is very fast. This stuff has all been well known for over 100 years. In fact long ago one of the easy ways to make formic acid in the lab was to take oxalic acid and glycerin, which were both easier to get than formic acid, and simply heat the solution a bit above 100 deg C and distill out the formic acid as it forms.

So, am I surprise you and others smell something that smells like formic acid on oxalic acid in glycerin strips? No surprise at all. You would need to be really careful how you made them to avoid making any formic acid and even then on storage in a sealed container I would expect some formic acid to be made at room temp given enough time. I suspect at least some of the failures of such strips to kill mites is because they were over heated during preparation resulting in strips with little oxalic acid remaining.

This tells the temperature tale.
 

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OK thanks guys. I very much appreciate that detailed hgelp, and it does seem that I likely overheated it.

I did not know that the process of converting into formic acid could continue even at room temperature.

Re the role of water, I recall from some years back that at one point Randy Oliver was adding a little water to his mix, then later, i think, he stopped adding water. But I can't find the references about that. Does anyone know what the rational for that was?
 

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We posted at the same time, great video Crofter. :)
 

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Johno I have posted that info to our local forum, much thanks to whoever the "mystery donor" of that information was, much appreciated.

And Crofter i have also linked your video in our local forum and had favorable comments on that also. Nice, simple, well presented video with no fluff.
 

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No Problem OT, the mystery donor was apparently banned for telling some idiot that that he did not know what he was talking about, if this continues there may not be many folks allowed to contribute to this forum
 

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I am glad this thread came back to life. I have had a lot of success with this method and have used this as my only mite reduction method for the past three years. I did some work with Randy O. originally and personally found that using strips hung between the frames was much more effective on the hive. Randy did not think this was a feasible method for a commercial beekeeper and wanted to pursue something faster. I am a sideliner with 20ish hives, not hundreds or thousands.

The Shop Towels may not be the perfect delivery method but they are cheap and working for me until a better solution comes along. I tried the cardboard, chipboard, and others more similar to what Maggi used and found it took much more time to cut it down to size prior to prep than it was worth. So I decided to take the shop towels and fold them into strips. Admittedly this is not a fast method for a commercial beekeeper either. I hang the strips on the frames by draping the end of one strip over the top and letting the long end hang down. You could also evenly hang a strip and not have the shop towel reach the bottom of the frame.

I feel like we need to get a strip solution that works like Apivar (with the plastic frame holder on the top) that has OA embedded in plastic or something that can be sold/packaged commercially. Basically this Shop Towel strip method is using the same in between frame method that the Apivar strips use.

I found the long release of this method keeps the mites low across multiple brood cycles and keeps killing for weeks, and the fact you can use it with honey supers on is great. I live in Florida where we don't get much of a natural brood break to use other methods effectively that require no capped brood.

Here are a few pictures of some things I have tried. NOTE: I no longer lay the towels on top of the frames as Randy originally tested. It makes a mess when you want to inspect the hive, and basically ruins your towels. If they are hung between frames you can inspect and leave the towels in place for multiple weeks/months until the bees remove them.

IMG_20180302_092607.jpg
Strip1.jpg

NOTE: See how the strips applied below keep you from being able to do an inspection without destroying the OA Application. I no longer use this method.
IMG_20170226_113930.jpg
IMG_20170317_130908.jpg
 
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