oxalic acid - Vap or Trickle

[Erichalfbee]

Then your doing it wrong, best applied warm think it helps with the take up

I think it was a joke?

 

[Ian123]

I think it was a joke?

Hence the wink!!

 

[richardh]

Interesting discussion.

Following local mentors, I started out gaping from beneath mesh floor but switched to entrance after noticing that a significant proportion of the vapour condenses immediately on the mesh floor, ultimately corroding it and significantly reducing the dose reaching the bees. In very cold weather I can imagine much of the vapour condensing on the frames before it reaches the cluster, more especially so if you're overwintering on a double brood.

 

[richardh]

Interesting discussion.

Following local mentors, I started out gaping from beneath mesh floor but switched to entrance after noticing that a significant proportion of the vapour condenses immediately on the mesh floor, ultimately corroding it and significantly reducing the dose reaching the bees. In very cold weather I can imagine much of the vapour condensing on the frames before it reaches the cluster, more especially so if you're overwintering on a double brood.

Sorry.. VAPING - spellchecker at work again!

 

[blackcloud]

If its condensing too quickly then it's too cold.
If you really have no other choice then administer through an eke from above

 

[jenkinsbrynmair]

Interesting discussion.

Following local mentors, I started out gaping from beneath mesh floor but switched to entrance after noticing that a significant proportion of the vapour condenses immediately on the mesh floor, ultimately corroding it and significantly reducing the dose reaching the bees. In very cold weather I can imagine much of the vapour condensing on the frames before it reaches the cluster, more especially so if you're overwintering on a double brood.

I've been sublimating from under the OMF for over a decade, definitely not found a 'significant' proportion of OA desublimating (it doesn't condense) on the OMF, often finding next to none on the tray. I've still got the original galvanised mesh on the floors and apart from the area directly above the pan there is no apparent corrosion, the floors will be good for many years again. I would contest your imagining that there is a significant reduction in the dose, even with a double brood (I've treated these as well) and I've witnessed the sublimate escaping from the upper levels in many I have treated. The solution of course is to increase the dose from the 'optimum' 2.25g per hive (regardless of hive size).

 

[Mabee]

In that minute I withdraw several yards upwind so do not wear a mask.

i’m interested to know why you wouldn’t just wear a mask? i’m in full face mask when I do mine, i’d much rather be safe than sorry!

 

[drex]

I am same as Amari. The lead on my pan vape is about 8 ft long. I load it cold. Put in hive, withdraw upwind, connect to battery for 3 mins, disconnect and wait a ccouple of mins, remove wand.

I am never in contact with the sublimated OA. Common sense. Have worked with hazardous chemicals lifelong.
If you wish to wear a mask, good on you

 

[The Poot]

I am same as Amari. The lead on my pan vape is about 8 ft long. I load it cold. Put in hive, withdraw upwind, connect to battery for 3 mins, disconnect and wait a ccouple of mins, remove wand.

I am never in contact with the sublimated OA. Common sense. Have worked with hazardous chemicals lifelong.
If you wish to wear a mask, good on you

Same here.

 

[Amari]

i’m interested to know why you wouldn’t just wear a mask? i’m in full face mask when I do mine, i’d much rather be safe than sorry!

Using a pan I find that very little vapour escapes the hive and never reaches me standing several yards away.
Vaping with a GasVap is totally different - can't escape the fumes so I wear a mask with filters.

 

[hemo]

Sunday/ Monday are my days for vaping, rain expected and 10/11c temps expected so pretty ideal. All on UFE's and have yet to corrode a mesh floor, my pan is enclosed under the UFE so only cooling effect is that from withn the hive. The parasol will be employed for use in the rain over each colony.

 

[blackcloud]

Its MAqs that has a penchant for mesh destruction.The only three doses I ever gave of that stuff resulted in the only three meshes I've ever had to replace

 

[richardh]

To close out my contribution to this discussion of OAV.. ..

Firstly, it never hurts to remind ourselves of the science and for this I find Randy Oliver's site (and linked PPT) useful:
https://scientificbeekeeping.com/oxalic-acid-heat-vaporization-and-other-methods-part-2-of-2-parts/
Of particular interest: OA sublimes at 189 Celsius from which it may be inferred that recrystallisation into a fog of airborne crystals, within the hive or outside it, is virtually instantaneous, regardless of season. Provide a cold surface immediately adjacent to the pan, as in vaporising beneath the mesh floor, and you'll inevitably reduce the dose reaching the bees, as I proved to myself again yesterday (I didn't measure the dosage loss because I don't have a suitable field weighing scale).

Why would you wittingly dose at less than the recommended level? Well, most of us probably wouldn't, and therein lies another interesting fact: the graph on Randy's page seems to indicate that OAV is equally effective at half and full recommended dose. This likely explains why, in practice, it's good enough to vape from beneath the mesh floor. It's certainly easier, operationally, do do that than (as in my case) levering-out a tight entrance block! That said, I won't be treating from beneath the mesh floor again.

And finally, I find it fascinating that such a high airborne load of OA is not toxic to the bees. Again, from the image on Randy's page, it's apparent that the bees tolerate OA depositing directly on the hairs that cover parts of their bodies. The physiological component of that tolerance is certainly a genetic trait, which I would guess is far surpassed during OA vaporisation - after all, it's pure OA crystals that collects on the bees. Note, in the same article, the implied limited tolerance to OA ingestion in sugar solution.

So how do we account for the apparent "excess OA tolerance" in vapour form, which surely exceed levels normally encountered in the natural environment? I wonder if it's down to the bee's spiracles (breathing holes) being smaller than most of the airborne OA crystals? Any research articles on this?

 

[richardh]

PS: under-dosing is more likely to lead to resistance in mites.

 

[Erichalfbee]

PS: under-dosing is more likely to lead to resistance in mites.

Not with Oxalic. I don’t think you can build a resistance to burnt feet and mouthparts.

 

[Anduril]

PS: under-dosing is more likely to lead to resistance in mites.

Oxalic is an acid, it won't lead to resistance. I've looked at Randy Olivers graph and both the orange and the red lines are above the US recommended dose which is 1g per brood box, from the results of a 1g dosage we would have seen a resistance by now in the US, that hasn't happened. The dose in the graph is 1.4g and 2.8g. European recommendations are around 2.3g per brood box. For a better understanding of OAV may I recommend Aficionados of oxalic sublimation

 

[Abelha]

Sunday/ Monday are my days for vaping, rain expected and 10/11c temps expected so pretty ideal. All on UFE's and have yet to corrode a mesh floor, my pan is enclosed under the UFE so only cooling effect is that from withn the hive. The parasol will be employed for use in the rain over each colony.

Not a “parasol” there won’t be much sol around

 

[jenkinsbrynmair]

PS: under-dosing is more likely to lead to resistance in mites.

there has been no evidence (regardless of dose) that mites can build up a resistance to OA

 

[Swarm]

Not a “parasol” there won’t be much sol around

Tuesday is a drier bet.

 

[hemo]

No vaping today , still blinking well freezing here , rain showers forecast Mon - Thur and near double temps so parasol will be used tomorrow and get all the vaping out of the way.