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 dehydrate the glue, making it more brittle and easier to crack apart. Steam can also be used to soften glue and separate joints. Specific types include "hide glue", "bone glue", "fish glue", "rabbit skin glue". Hide glue is used in woodworking. It may be supplied as granules, flakes, or flat sheets, which have an indefinite shelf life if kept dry. It is dissolved in water, heated and applied warm, typically around 60°C (140°F). Warmer temperatures quickly destroy the strength of hide glue. Commercial glue pots, simple water baths or double boilers may be used to keep the glue hot while