# Anyone doing OAV treatments from top of hive?



## Kiran (Jan 27, 2014)

I do that. It works.

It is much easier to set and I want to think it is even more effective since crystals precipitate downwards. I have screened inner-covers, on top I put a 3" notched spacer and cover. I put the vaporizer right on top of the inner-cover.


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## Arnie (Jan 30, 2014)

Yes, you can do it just as you described. It works fine.


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## FlowerPlanter (Aug 3, 2011)

https://www.youtube.com/watch?v=ALHz4B1vqKo

IMO if you have to treat this is the way to do it, might be safer and you can see what going on.


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## JWChesnut (Jul 31, 2013)

I generate ten frame starter hives with a drilled hole entrance on the body instead of a bottom board. I OAV these with a 1 inch shim with a slot for the heater device. I have 5 of theses so the vapor has the chance to crystallize and settle as I move to the next box. This works fine.


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## Daniel Y (Sep 12, 2011)

I've heard of someone vaporizing from the top of the hive. Does anyone do that? What's the technique?

Yes. Put the stuff at the top of the hive rather than the bottom, he he. Okay seriously. I make a box to place all the stuff in. it is about 9 inches deep and takes care of all the burning stuff issues. I have never done it with my "Magic Wand" but have vaporized OA over a tea candle this way. 

Is it just as effective as placing vaporizer on bottom board?

Yes. OA coming out the entrance (at the bottom) coupled with the top of the box being glass is know I know it gets all the way through the hive.

What if I made a 3" spacer with a notch for the vaporizer handle and sat it above top deep, sat vaporizer on top bars (with a small sheet of aluminum to protect wood), closed off bottom entrance, etc. etc.

Yep that sounds about like it. except I would go with about 6 inch deep spacers or more. Folded aluminum foil makes a remarkable insulator. I place a tea candle on foil. place a holder for a second tea candle cup over that. place OA in the upper cup and walk away. I can just leave the mess to burn up. I also place a screen around the candle to keep flaming bees from running through the hive. It is all part of how I designed the upper cup holder. So it is like this. Remove outer and inner cover. place a folded piece of aluminum foil on top bars. place tea candle on aluminum foil. Light candle. place upper cup and holder over tea candle with a dose of OA in it. No rush here the candle will burn for an hour. Place top on spacer and leave for 5 minutes. You can return at that point and blow out the candle and let it all cool. note wax is now molten so give it a minute or two. or just let the candle burn up and return at your convenience. I would suggest removing spacer and candle by the end of the day but if you are doing hundreds of these you may not get back much before sundown.

Vaporizing from the top of the hive would be much easier if it would be effective.
Bees fan the dust through the hive. I now call it dust because that is what it is. it is no longer vapor once it is about 1 inch from the hot surface. use of the tea cup will make that obvious. attempt to vaporize more than a two deep dose in this set up will prove it. OA has to remain in contact with teh hot surface of the cup to vaporize. In the event I do need more than a two deep dose I use two candles and holders. at 5 cents each I am not going broke any time soon. Worst part is if you had 100 hives and wanted to treat all of them in one run you might need 20 or so spacers. you can make them from pretty much any trash you find to make them from. They could be cardboard if you add some aluminum foil to the ceiling of it.

Height of OA cup above flame is important so test your design. to high and OA will not vaporize. to low and it puts out the flame. Candle is not reusable OA cup and stand is. But then every candle used provides materials for a new stand. Save them, you may decide to not save used stands. Metal window screen will serve as the screen to keep bees out of flame.

I like to have cups with the dose already in them and just go through hives one after the other. Tip: hold the candle to light it. avoid burnt fingers that way.


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## Scitfrostbite (Aug 15, 2015)

I'm hoping this works. I made this and test fired it on top of an empty deep. Thoughts?
I hope it solves several problems compared to bottom vaporizing--
-Fire caused by wax dripping into vaporizer
-Less frying of bees
-Easier to set up (just pull off cover and replace with OAV spacer)
-Plexi top provides view for confirmation of burn


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## cervus (May 8, 2016)

Still can't understand the concern with fire using a vaporizer the correct way. OA sublimes at ~315F. Flashpoint of beeswax is 400F. You'd have to leave the vaporizer energized for quite a while longer than recommended to achieve a 85 degree delta to ignite wax. It seems like there would be lots of posts on hives going up in flames, but I've yet to see any. Vapors rise, so I'm thinking bottom-up is probably much more efficient for dispersing the vapors.


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## Scitfrostbite (Aug 15, 2015)

cervus said:


> Still can't understand the concern with fire using a vaporizer the correct way. OA sublimes at ~315F. Flashpoint of beeswax is 400F. You'd have to leave the vaporizer energized for quite a while longer than recommended to achieve a 85 degree delta to ignite wax. It seems like there would be lots of posts on hives going up in flames, but I've yet to see any. Vapors rise, so I'm thinking bottom-up is probably much more efficient for dispersing the vapors.


Yep, I'd never heard of vaporizing causing a fire until recently on beesource (I think). Also, I was at a association meeting recently where someone showed some charred frames from a vaporizer. But, really my main reason to think about vaporizing from above is just to be able to more easily insert the vaporizer.


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## cervus (May 8, 2016)

I'm sure it's happened somewhere at some point (fire). Your set-up looks like it should work fine. If the acid crystalizes and precipitates down along with bee movement/contact, both ways should be pretty equal in terms of effectiveness. I just like the idea of a "drive-by" treatment, without so much as removing the top cover.


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## JTGaraas (Jun 7, 2014)

Vaporization from the top is absolutely acceptable and effective. I have created a three (3") shim with handle gap, and I use a piece of acrylic plastic as the cover. I can observe the vaporization as it rises, and then watch as it pours downward into the hive. I can also see when the oxalix acid is liquified, and a couple of jiggles to the handle will help complete the vaporization process toward the end of the cycle - it is quite often that the heat will cause the acid to have a little crust that sorta dams up some of the liquid late in the cycle. The jiggling causes the liquid to spill unto a hotter area so as to instantly vaporize it so all is consumed.
Always wear the appropriate respirator and eye protection - without fail!!!


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## Daniel Y (Sep 12, 2011)

cervus said:


> Still can't understand the concern with fire using a vaporizer the correct way. OA sublimes at ~315F. Flashpoint of beeswax is 400F. You'd have to leave the vaporizer energized for quite a while longer than recommended to achieve a 85 degree delta to ignite wax. It seems like there would be lots of posts on hives going up in flames, but I've yet to see any. Vapors rise, so I'm thinking bottom-up is probably much more efficient for dispersing the vapors.


That OA sublimates at 315 degrees does not mean the hot plate is limited to 315 degrees. It could and most likely would reach temperatures of well above the flash point of beeswax.


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## GSkip (Dec 28, 2014)

Yes you can treat from the top. I too use a shim with a notch for the handle. As has been stated the vapor turns to crystals and cover the inside. In a day or so the bees have cleaned up all the crystals. The way my hives are arranged I find it easier to treat from the top.


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## cervus (May 8, 2016)

Daniel Y said:


> That OA sublimates at 315 degrees does not mean the hot plate is limited to 315 degrees. It could and most likely would reach temperatures of well above the flash point of beeswax.


It takes my vaporizer ~ 2 minutes to vaporize 2 grams of OA. That's when the device and the OA reach and equilibrium temperature. I unplug after 2 minutes. The operative term in my comment was "recommended". It's impossible for the plate to exceed 400 degrees F when it's not energized. Those with homebrew OAV devices...your mileage may vary.


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## larrypeterson (Aug 22, 2015)

If I may,

I used oav on a colony that had a top entrance this Spring. The burner scorched the lid and the top of two frames. I have remodeled several bottom boards to allow a 4 inch insert in the rear so I can close the front entrance and "sneak" the vaporizer in from the back of the hive boxes. I plan to "knock down the varroa mite count again in October. I think the rear attack will work just fine.

I wish you well, LP


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## Daniel Y (Sep 12, 2011)

cervus said:


> It takes my vaporizer ~ 2 minutes to vaporize 2 grams of OA. That's when the device and the OA reach and equilibrium temperature. I unplug after 2 minutes. The operative term in my comment was "recommended". It's impossible for the plate to exceed 400 degrees F when it's not energized. Those with homebrew OAV devices...your mileage may vary.


So when I boil water on an electric range where the heating coil is red hot. The water never gets above 212 degrees at which point it boils turns to steam and removes heat from the pot. The burner if set to high and glowing red is about 1200 degrees. it has been since it started glowing. So your device could be and probably is well above the 400 degrees the entire time it takes to get the OA to vaporize.


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## cervus (May 8, 2016)

Daniel Y said:


> So when I boil water on an electric range where the heating coil is red hot. The water never gets above 212 degrees at which point it boils turns to steam and removes heat from the pot. The burner if set to high and glowing red is about 1200 degrees. it has been since it started glowing. So your device could be and probably is well above the 400 degrees the entire time it takes to get the OA to vaporize.


That's a pretty good analogy apart from the mass involved, the intervening container holding the water, and the temperature deltas. Someone needs to do a test. If I had a laser thermometer, I'd do one today. It may exceed 400 degrees F during the 2 minutes or so it takes to vaporize the OA. I just don't think it does create a fire hazard, top or bottom treatment, or there would be dozens if not hundreds of hives going up in flames. I could be completely wrong. It wouldn't be the first time. But I'm open to facts.


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## viesest (Jul 13, 2016)

One test. I heated up sublimator (as for sublimation), and put some wax on it. There was no flame just smoke.


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## crofter (May 5, 2011)

The problem with using an analogy as a proof of fact, is that so very often the analogy is not a very close parallel to the argument it is supposed to support!

Cervus has valid points. Usually there is a point of equilibrium where heat input and heat dissipation even out to a stable temperature. With a good design it will reach an effective temperature quite quickly without dangerously overshooting within any reasonable time frame.

It is all to easy to come up with a hunch, admire it from a few limited angles, accept it as fact and build upon that assumption. Problem when its is not factual.

There is approaching 100 F. degrees temperature difference between the flash point and the autoignition point of bees wax. I have one model that would scorch bottom boards quite significantly but would melt and boil off wax without igniting it. A simple plate underneath with about a sixteenth of an inch air gap cured the bottom scorching. It now looks very similar to one of the well recommended patent models. Just a bit more mass so a bit slower to reach sublimation temperature but the dissipating area and the heat input energy are well enough balanced to keep temperatures from running away. Many of the homemade ones might not stabilize so.

It would be a good test to do as Viesnest suggests to test your model.

I have not done top vaporizing but see no problem with dissipation throughout the hive. Relative to the bees fanning horsepower input, the weight of the smoke compared to the weight of air in the hive is insignificant.


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## Michael Bush (Aug 2, 2002)

I haven't in more than a decade, but I did it from the top when I used OAV and it worked fine.


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## BernhardHeuvel (Mar 13, 2013)

Testing a new oxalic acid sublimation device...works from the top.





https://www.youtube.com/watch?v=nT3lp1Y0Rgg

Works with butane gas, oxalic acid vapor is circulated by a small ventilator and the special hood, so the oav gets into every corner of that hive, 3 minutes per hive, doesn't need external power, ...

Still in phase of development, but promising so far. I like it. Little vapor outside the hive, a defined dosage of oxalic acid gets sublimated and is circulated through the hive. Bees are covered in tiny oxalic acid crystals, mite drop is pretty strong.


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## bsharp (Feb 5, 2013)

BernhardHeuvel said:


> Testing a new oxalic acid sublimation device...works from the top.
> 
> 
> 
> ...


THAT is cool! Is this something that you're (or someone is) developing commercially?


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## BernhardHeuvel (Mar 13, 2013)

Developed and sold commercially. Semi-commercially that is. No, not me. 





https://www.youtube.com/watch?v=2mx34L9LxYQ

I love it. I work four pallets ahead and pull the vaporizers behind me. The fan inside circulates the oxalic acid crystals all over the hive, really every single bee is powdered lightly.


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## JeronimoJC (Jul 21, 2016)

Bernhard, 
Is it safe to assume that when using this device some cristallization takes place inside the hood, but this isn't a significant issue?


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## BernhardHeuvel (Mar 13, 2013)

Yes, that is right. The more hives you use it on, the more oxalic acid builds up. But it is rather loose and can be wiped off.

The producer of that device is Erich Alfranseder. See: http://alfranseder.de


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## Cristian (Jul 28, 2014)

Hmm , 6 min/hive/treatment is a little bit to much ! . This means that I could treat a yard of 40 in 4 hours !!! . Things will work with 4 machines . One yard/hour is much better , plus that is a not so expensive machine .
What treatment scheme is used with this vaporizer ? .


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## BernhardHeuvel (Mar 13, 2013)

No – the 6 minutes per hive is the electrical version of the Oxamat. The butane gas version needs only 3 minutes. I do 60-100 hives a day, checking, feeding and treating in one go. I pull the device about four pallets behind me. So I work forward and treat behind me. I use two devices and plan to buy two more, so I can go faster.

That is the electrical version of the Oxamat. I use it for my Warré hives. As you can see, it is much slower. But the temperature is much better controlled.





https://www.youtube.com/watch?v=wdsbClU0y6I

It uses a car battery and a headlamp bulb as a heat source. The pan sits on the bulb, needs to cool off before reusing it.


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## Pooh Bear (Jun 19, 2015)

Awesome post and quite timely. I treated two hives last night from the top and found it to be a lot easier. Thanks for putting this post up as I never even thought about that approach.

Also, when I treated from the bottom earlier this year, the bottom slatted rack was all carbonized locally from the heat and the nearest two frames had localized wax melting and brood loss too. It got pretty hot it seems. Treating from top with a foil insulator is so much easier and safer- genius! A lot less chance of a fire that's for sure.


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## Scitfrostbite (Aug 15, 2015)

I've now used my plexiglass topped box to treat about ten times. It seems to work well. I like how I don't have to struggle removing propolized entrance reducers and no damage to the frames.

I wonder though how good the circulation of the vapor is when I'm doing it from above. I don't see vapor coming out cracks low on the hive like how I see vapor escaping around the cover when I treat from below. Since the vapor is hot initially, does it cool and fall down to the bottom of the hive? I would feel better about this top treatment if I saw some OA at the entrance, or maybe it get carried around by the bees anyway?


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## BernhardHeuvel (Mar 13, 2013)

See the video. The device has a small fan that circulates the vapor throughout the hive. It ensures that every single bee in that hive is covered in oxalic acid crystals making the application very effective. If in doubt, repeat treatment or use 2 gramm (doubled dosage).


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## Scitfrostbite (Aug 15, 2015)

Thanks, I wasn't talking about that device that you posted. I was talking about using a OAV wand.


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## Arnie (Jan 30, 2014)

Scitfrostbite said:


> Thanks, I wasn't talking about that device that you posted. I was talking about using a OAV wand.


The OAV wand will work from the top.


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## snl (Nov 20, 2009)

Arnie said:


> The OAV wand will work from the top.


I actually prefer doing it from the top down. No bending or stooping. Just make a 2" or so shim, cut a slot in it for the Vap rod, place a 4"x4" or so 1/4 piece of plywood on the frames (to keep them from scorching/melting) place the Vap on the plywood, cover with the inverted top cover and vaporize.


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