Propolis propolis has approximately 50 constituents, primarily resins and vegetable balsams (50%), waxes (30%), essential oils (10%), and pollen (5%). Propolis also contains persistent lipophilic acaricides, a natural pesticide that deters mite infestations. In neotropical regions, in addition to a large variety of trees, bees may also gather resin from flowers in the genera "Clusia" and "Dalechampia", which are the only known plant genera that produce floral resins to attract pollinators. "Clusia" resin contains polyprenylated benzophenones. In some areas of Chile and Argentina Andean valleys, propolis contains viscidone, a terpene from "Baccharis" shrubs, and in Brazil and Paraguay, naphthoquinone epoxide has
Animal glue in use. As hide glue cools, it gels quickly. At room temperature, prepared hide glue has the consistency of stiff gelatin, which is in fact a similar composition. Gelled hide glue does not have significant strength, so it is vital to apply the glue, fit the pieces, and hold them steady before the glue temperature drops much below 50 °C (120 °F). All glues have an "open time", the amount of time the glue remains liquid and workable. Joining parts after the open time is expired results in a weak bond. Hide glue's open time is usually a minute or