Special or Unusual Frames
Brooks-Knight Frame
Thymol Crystals
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Frakno Frame for Thymol Crystal Evaporation

Frakno Thymol Frame

The document, with the white background, that is reproduced below was issued to purchasers of the device by:-
E.H. THORNE (Beehives) LTD. I am not responsible for it's wording and I have no links with the company.


1.   Sprinkle 12g of Thymol crystals through the mesh onto the filter cloth, below, ensuring maximum surface area coverage.

2.   Remove one frame from the side of the brood box and replace with the THYMOL FRAME. If your hive is a warm way configuration place the frame as far away from the entrance as possible.

3.   Once all the crystals have evaporated remove the frame.

4.   Treatments should be carried out twice a year, once during the first two weeks of May and the second time at the end of July and beginning of August.

5.   Thymol does not kill varroa mites. It does, however, upset its reproductive system. The female cannot mate within the cell of the bee and once it emerges with the young bee, it falls from the comb and dies and cannot, therefore infest another cell.

6.   Thymol is an anti-fungicide and as such is particularly useful in controlling chalkbrood.

7.   To slow down the build up of propolis on the epoxy mesh and the fume chamber slits it is beneficial to smear these areas with petroleum jelly.

8.   It is useful to place a sheet of B.S. Shallow Wired Drone Base foundation in the lower half to attract the mites to the frame.

We would recommend alternating treatments between Thymol and Bayvarol each year.

The chamber that the crystals are placed in has a fine nylon mesh base that acts as a diffusing screen. The wooden member with slots that is immediately under this chamber causes further diffusion and slows down any draught that could cause evaporation (sublimation of the thymol crystals) at too high a rate. The slots are nominal 3 mm wide saw cuts.

If I were making a batch of these I would use net curtain material for the base of the evaporation chamber.

I use small woodscrews (#4), rather than gimp pins, to clamp the twin foundation retaining bars firmly to the foundation.

A report (1998) from the Swiss Dairy Institute, entitled "Residues in honey after application of thymol against Varroa using the Frakno Thymol frame" is available online.

Caution:-  Thymol is a powerful disinfectant and causes burns, is harmful if swallowed, avoid contact with the skin and eyes, use gloves and goggles, and after contact with the skin wash immediately with plenty of water.

Originally written by Dave Cushman.

Page created 24/02/2002

Page updated 21/08/2022