Propolis while also collecting water and tree resin necessary for the production of propolis. The chemical composition and nature of propolis depend on environmental conditions and harvested resources. For centuries, beekeepers assumed that bees sealed the beehive with propolis to protect the colony from the elements, such as rain and cold winter drafts. However, 20th century research revealed that bees not only survive, but also thrive, with increased ventilation during the winter months throughout most temperate regions of the world. Propolis properties may include: The composition of propolis varies from hive to hive, from district to district, and from season to
Glue-size high perishability of linen cloth and the solubility of hide glue. Well-known and relatively well-preserved — though substantially damaged — the most notable examples include Quentin Matsys' "Virgin and Child with Saints Barbara and Catherine" (c. 1515-25) and Dirk Bouts' "Entombment" (c. 1440-55). In German the technique is known as "Tüchleinfarben", meaning “small cloth colours”, or "Tüchlein", derived from the German words "Tüch" and "Lein" ("fabric" and "flax"). A binding agent for pigment was made by boiling animal skin mixed with other organic tissue and applied to linen, itself prepared with a thin layer of glue. The linen was ground,