Oxalic acid vaporiser and open mesh floor

[Arfermo]

You can download the instructions for the process from the Varrox web site then assess whether it is for you.
http://www.biovet.ch/en/Imkerei/varrox-vaporizer.html

I use it and like the speed and ease of use. Just a couple of warnings. Oxalic acid fumes are dangerous, so use some common sense and protective gear.
The fumes can also condense on the mesh floor if you place the Varrox UNDER the mesh as I do so the bees have less chance of being 'fried'. (I made a 'special' varroa type tray) So you may be better replacing the std varroa floor with stainless steel mash (supplied by the "mesh company") as the acid will not initiate corrosion on stainless as it will on 'zintex' standard mesh.
Hope this makes sense.

Exactly the same modus operandi that I have always used - varrox under omf on a 2mm sheet of steel that slides in where the varroa tray goes and stuff every aperture bar the entrance to seal the hive during treatment - 2 1/2 mins. After treatment, out with steel sheet and in with tray.

 

[Arfermo]

James do you block off your open mess floors before using the vaporiser and if so how do you do it? I emailed one distributor of the product and they said that you should not use it with an open mesh floor at all as the vapour will escape and therefore not be effective.

Silly advice - see my post above. Stuff the space around the evaporator/varrox - I use a foam insert approx 1" x 1" but a rag would do equally well. What else!!!!

 

[sussexbaker]

The problems is that it is a Phd student research project so they are very careful not to release too many facts

they have tested a control against three weights of oxalic dihydrate 2g, 3,25g and 4g in balanced hives and sampled varroa on 200 bees before and after, this was compared to oxalic in sugar solution applied by spray and by dribble insimilar balanced hives

the gave the % mite kills, but on worker bee losses and Queen losses!! i cannot remmeber whether they said how these were calculated

I did email and ask them for the presentation deck but not had a reply. My notes from it are that they looked at colony survival, not at individual worker or queen losses. The talk of bee fatality was anecdotal rather then backed up with numbers (as I mentioned in the thread about treating above certain temperatures). IIRC the advantage of treating from underneath the OMF was that you didn't burn anything with the hot vaporiser.

As for borrowing a Varrox, if we can sort out timings and logistics I'm happy to lend you mine. And as a bonus your plan is exactly what I'm doing (as it'll melt through my poly hives).

 

[midnight sun]

I'd be interested in seeing the numbers. All the Varrox instructions and videos make no mention of anything other than in through the entrance above the floor, similarly the Canadian Heilyser and other makes mentioned around the web. I can't see how passing the vapour through a cold mesh won't affect the amount and distribution in the hive. It could be that a smaller or cooler dose is still effective of course, but should that lead to reducing the total dose rather than giving a partial dose through an obstruction?

If you apply oxalic by mixing with sugar syrup and drizzling the bees with 5mls per seam, how much runs out of the hive floor and is wasted? Or overdoses one bee and misses another?
How much of a dose does each bee get?
The method I have described is perfectly ok. If you see a little escape from the edges of the roof say, it means it has reached those points. Heat rises and so does the vapour which is 'hot' and then the convection currents disperse it out and to lower parts as is 'cools'. Don't forget that once sublimation has occurred , the 'gas' condenses back into fine crystals coating everything in the hive that it touches. Also don't forget about the bees fanning the stuff all over the place (you can hear them) assisting in the dispersal).
If you argue that the small amount which crystalizes on the mesh floor affects the dosage, then what about the amount that crystalizes on the bottom of the nearest frame it touches by the other method of putting the Varrox through the entrance? (and roasting some of the girls in the process)
Don't worry, there is enough to do the job. You need to see it working to truly appraise the method and not just theorizes on it's merits.

 

[tresallier]

I use a home built sublimator. £45 for the heat gun off fleabay and 20 a few plumbing fittings - the most important being an in line filter - this has a stainless steel mesh filter that I have blocked off with a 10p piece (no expense spared) into this I put some oxalic acid crystals. The heat gun is adjustable so I can run it at 180C as if you heat oxalic to hot it turns to formic acid.

I have semi omf floors - in as much as the hive is on a pallet with the gaps covered in stainless steel mesh (soffit vent) the white board is a bit of card to catch and so monitor the drop.

At my home apiary an extension lead suffices. As we live in one of those areas of Hampshire that have an internet connection poorer than a west African mud hut and regularly get Christmas refunds from the electricity people for loss of supply - we have a generator - which suits the out apiary on a farm.

I have used many kgs of oxalic in my working life (as an organic bleach) - yes it is poisonous and yes you can inhale the fumes - but you will find the most minute quantity will make you cough so you will move away rapidly. (I started working with the stuff at 19 and am now nearly 60)

 

[itma]

I use a home built sublimator. £45 for the heat gun off fleabay …

OOOH !!
Never mind the Oxalic, that hot air gun is amazing! Never realised such things existed - but now I do, I think I might need one, even if I actually only want one … time for some "bargin" hunting!

 

[mbc]

OOOH !!
Never mind the Oxalic, that hot air gun is amazing! Never realised such things existed - but now I do, I think I might need one, even if I actually only want one … time for some "bargin" hunting!

If you have a grand to spare you can get a cordless one.

 

[itma]

If you have a grand to spare you can get a cordless one.

I think I could put up with a cable …
And I'll even wait to see if one appears for less than £60 + shipping … but it definitely has a place on a wish list.

 

[mbc]

If you have a grand to spare you can get a cordless one.

Or only £100 if you go for a hybrid gas/catalyst battery fan one

 

[TryingToLetThemBee]

I use a home built sublimator. £45 for the heat gun off fleabay and 20 a few plumbing fittings - the most important being an in line filter - this has a stainless steel mesh filter that I have blocked off with a 10p piece (no expense spared) into this I put some oxalic acid crystals. The heat gun is adjustable so I can run it at 180C as if you heat oxalic to hot it turns to formic acid.



I have semi omf floors - in as much as the hive is on a pallet with the gaps covered in stainless steel mesh (soffit vent) the white board is a bit of card to catch and so monitor the drop.

Why does the hot air not cook the hive?

 

[user 6228]

Why does the hot air not cook the hive?

Its the temp rise is gun power multipled by time divided by the thermal capacity of the hive...
just think how much heat it takes to warm up a kilo of honey and there is 12kg+ in there plus the wood and the wax.

 

[TryingToLetThemBee]

Yes but the air is at 180C. It's not like just a pan of hot OA; it's a jet.

 

[user 6228]

Yes but the air is at 180C. It's not like just a pan of hot OA; it's a jet.

it gets mixed with the cool air as it escapes the nozzle. The high velocity promotes turbulent mixing
take a hot air gun and hold your hand 1 metre away from the nozzle. The gas hitting your hand is not hot.

I have succesfully dried a wet bee using a hot air gun, but it was held about 400mm away

 

[jenkinsbrynmair]

I have succesfully dried a wet bee using a hot air gun

Is that a regular occurence at bathtime? I just leave mine wrapped in their towels in front of the fire for ten minutes or so

 

[user 3509]

The instruction leaflet for the Varrox vaporiser talks about using the equipment on a hive with frames the warm way. My question is if you are using it under an open mesh floor will it make any difference if your frames are the cold way?

 

[midnight sun]

The instruction leaflet for the Varrox vaporiser talks about using the equipment on a hive with frames the warm way. My question is if you are using it under an open mesh floor will it make any difference if your frames are the cold way?

No.

 

[Bee Bumble]

The instruction leaflet for the Varrox vaporiser talks about using the equipment on a hive with frames the warm way. My question is if you are using it under an open mesh floor will it make any difference if your frames are the cold way?

No, does not matter which way the frames are placed. We use a Varrox placed under the mesh floor, entrance blocked.

 

[colinrelf]

Seemed to work on some but lost a Queen in another. Would rather not use again.