Hive management in early spring to speed up brood production. Propolis is another byproduct of the bee hive. Certain races of bees are more prone to using propolis. Propolis can be collected on special plastic propolis screens. The tendency of the bees is to use propolis as a glue to seal openings that are too small for a bee to crawl through. A propolis screen is usually put in place of an inner cover. It has small openings that are propolized by the bees. The propolis screen can be frozen which hardens the propolis. Once the propolis is frozen it can be
Glue-size but sometimes treated, by both the glue and also white chalk, which allowed a surface suitable for underdrawing and a base that would not absorb the final layer's pigment. The advantage of using glue as a binder is that the colours render as matte and opaque textures suited to austere or mournful images as opposed to the translucent appearance associated with oil. Many reds and blues bound in glue would have appeared with a brilliance and intensity difficult to achieve with oil. Unfortunately the surviving examples have greatly deteriorated over time, having suffered from colour alteration due to exposure to