Oxalic Acid proportions

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Heather 

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Anyone who is thinking of using Oxalic Acid on that sunny day n December/Jan you have choices.
Buy the ready made up solution from your supplier or make up your own fresh solution
If you wish to make up your own you may wish to read this article. It is 1999, but I feel still relevant.

http://www.beedata.com/files/drip-oxalic-bogdanov.PDF

I have used 20 gm of the Oxalic powder accurately weighed with 500 mls of 1:1 syrup. This does 9-10 hives.

I have had good results and bees cope well, with no obvious death. This is a once a year treatment!.

Just thought to pass this on as I am making up a solution to treat yesterdays swarm that I hived.
 

Rosti 

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Heather, it is a good and timely post, thanks. I will be making up excess solution knowing it will be thrown away so that I can have greater assurance with regard oxalic weighing accuracy. To speed things up for other readers this is the summary from the trials Heather mentions (not sure if there is a geographic limitation on the validity of findings though - thoughts?):

Edit addition: Spray treatment better tolerated by bees but Dec / Jan will be cold anyway. lifting frames to spray - will this only increase short term stress and a slight increase in stores used or have an impact all of it's own?

RECOMMENDATIONS for the drip treatment with oxalic acid
(Switzerland and Central Europe)
Composition of the solution: 35 g oxalic acid dihydrate in 1 litre sugar syrup 1:1
Quantity: 30 ml for a small colony
40 ml for a medium colony
50 ml for a large colony
This quantity corresponds to 5 – 6 ml for each occupied bee-space of a Dadant or Swiss
hive.
Time of treatment: In broodless colonies (November – December)
Remarks:
· only one treatment in autumn
· drip the solution directly on the bees between the frames
· treat with lukewarm solution
· perform the treatment at an ambient temperature above 0o C
· use only freshly prepared solutions or solutions that have been stored for max. 6 months at
a maximum of 15o C
· under certain conditions, drip treatment with oxalic acid may slightly weaken the colonies in
spring.
The spray treatment with oxalic acid is better tolerated by the bees (30 g OA dihydrate / litre
water, 3-4 ml per occupied frame side); description of spraying method and results see [4];
· wear gloves and safety goggles during the treatment
 
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Heather 

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And does anyone know whether the expiry date on Oxalic crystals is to be accurately stuck to- or is it a jobs worth number (like honey expiry date on shop labelling:smilielol5:).
My Oxalic crystals expired 6 months ago. Stored in dark dry cupboard. I wont risk using 'old' if critical -but it may be a number they have chosen!
 

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And does anyone know whether the expiry date on Oxalic crystals is to be accurately stuck to- or is it a jobs worth number (like honey expiry date on shop labelling:smilielol5:).
My Oxalic crystals expired 6 months ago. Stored in dark dry cupboard. I wont risk using 'old' if critical -but it may be a number they have chosen!
As far as I can ascertain, the problem is that is is hygroscopic; and if it has managed to absorb any water, it's then subject to the same instability as the solution.

So... do ya feel lucky, punk? Well, do ya?:)
 

Heather 

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Its dry - I is a lucky lady...
Just treated swarm with it so will see if effective now before my winter colonies
 

Black Comb 

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Can you please advise best source of oxalic crystals / powder.
Thanks.
 

admin 

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I think I got mine from c wynne Jones.

Beekeeping suplies dot co. uk
 

oliver90owner 

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Bonnymans.

Half the price or twice a smuch! More than you are likely ever to need.

Regards, RAB
 

WI-USA-BEEK 

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So did I read right that the crystals go bad? Only if they absorb water? I ask because I had a hard time finding them and when I did, it looked like the container had about 12 years worth of dust on it. Do I need to worry about its contents. It is in a sealed plastic container. But once I open I should replace every year or do I just need to make sure it stays dry?

Help, ignorant american here.
 

Heather 

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I have had mine 4 years- opened -used annually- resealed and kept in high kitchen cupboard - crystals still ok. Effective this September on a swarm. Just keep your powder dry :cheers2:
 

oliver90owner 

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So did I read right that the crystals go bad?

Depends a lot on what it was!

Oxalic acid is commonly available as di-hydrate - combined with two molecules of water.

Sooo, one may have to be careful as to the recipe used as the relative molecular weights are considerably different. Most recipes are not that clever to impart the true description (anhydrous or hydrated) but nearly all refer to the di-hydrate.

Oxalic acid is, or rather was, used as a volumetric standard material in the good old days of quantitative volumetric analysis.

Regards, RAB
 

WI-USA-BEEK 

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Hmm, im not sure what I got but Ill have to look when I get to farm. I have wood bleach crystals that sound large and dry when you shake container. I think it said 99.9? percent pure or whatever.
 

oliver90owner 

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99.9% could refer to either the anhydrous or the dihydrate!

Hygroscopic only means that the anhydrous would absorb moisture and change (in part) to the dihydrate. Only deliquescent substances absorb water in such quantities as to become sticky or wet.

RAB
 

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As far as I can ascertain, the problem is that is is hygroscopic; and if it has managed to absorb any water, it's then subject to the same instability as the solution.)
The problem with the solution is that in the presence of strong acids, sugar solution breaks down producing high levels of HMF (Hydroxymethylfurfural). The OA sugar syrup solution changes over time from a clear to a straw coloured or darker liquid. I believe that it is recommended that OA syrup solutions made up are used within one month or discarded.

Kept properly I am led to understand that OA crystals have a long life. If anyone tells you anything else, it's rhubarb . . . :)
 

onriver 

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Hi - fairly new to this and looking for advice - I've a just bought 50g bag of OA and looking to make up a solution for the traditional (at least for the past 2 years!) New Year's day treatment. My worry is that without scientific scales I'm going to have to estimate the weight of the OA for division and am concerned about the consequences of getting concentrations wrong. Has anybody else checked the accurate weighing of a standard bag sold as 50g?
thanks!
 

oliver90owner 

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Look at trading standards. They will give tolerances allowed for all sizes of package.

It will be fairly close and more likely over, but very slightly only.

Regards, RAB
 

onriver 

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thanks - I will do. The OA came from a small local enterprise so doesn't have the appropriate kitemarks! Just needed a bit of reassurance, I suppose
 

Hombre 

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Weighing OA with coins

Last year I had no accurate scales, so made myself a simple balance with a couple of food bags, some thick thread and a spare bottom bar. with the aid of a couple of coins, I got the balance correct.

Then using Google to find the weight of various UK coins and having assembled the correct weight in the bag on one side and the OA on the other, we were off and running.
 

MJBee 

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Amazon do/used to do a very accurate digital scale for about £10. I have one and use it regularly for Thymol crystals, Apiguard (bought bulk and need 50g doses) and Oxalic.
 

Ruary 

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Look at trading standards. They will give tolerances allowed for all sizes of package.

It will be fairly close and more likely over, but very slightly only.

Regards, RAB
If the package has the 'e mark' on it the average weight of the lot must be not less than the 50g stated. However an individual packet may be up to 18% less and still qualify. ( no packet must weigh less than the stated weight minus twice the tolerable negative error) and for up to 50 g the TNE is 9%.
The moral is to bite the bullet and buy an accurate scales.
Ruary
 
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