A propolis screen is a device that channels the bees' gap-sealing behaviour onto a surface that can be harvested.

The principle

Bees seal narrow gaps in the hive with propolis. A screen offers many small gaps and so collects that behaviour.

It is placed immediately above the frames, in place of the crown board.

Types

• Flexible plastic screen: The commonest. Because it bends, harvesting is easy
• Metal grid: Durable but does not flex; harvesting is more laborious
• Slatted timber: Spaced slats create the gaps

The gap size is critical: too wide and the bees fill it with comb, too narrow and they do not seal it with propolis.

Harvest

When the screen is full it is removed and frozen. Propolis becomes brittle in the cold; flexing the screen makes the pieces fall out.

At room temperature propolis is sticky and will not separate. Freezing is a required part of the method.

Conditions that increase production

• Cool weather: The tendency to seal increases with cold
• Autumn: Collection rises during preparation for winter
• A little light: Some beekeepers admit a small amount of light from above to stimulate sealing
• Genetics: Some lines collect markedly more

The drawback of scraping

Propolis scraped from frame lugs and hive surfaces contains wax, timber fragments and paint residue. Its quality is low.

Screen collection is required for food or health use.

Residues

Propolis from a hive under acaricide treatment may carry residues. Screens should be removed during treatment periods.

Storage

• Cool, dark and airtight
• Keeps well in a freezer
• Light and heat degrade its components

Records

Because composition depends on the source plants and varies by region, recording the source and the collection period is valuable for sale as well.