It is sometimes incorporated into praline, hazelnut paste, and other nut pastes. They come in many forms consisting of liquids, powders, gels, and pastes. Many markets in Mexico sell mole pastes and powders in packages or by the kilogram. Solder pastes used in electronics manufacturing printing processes are thixotropic. It is used as an ingredient for certain northern Thai salads, curries, and chili pastes. Examples of rheopectic fluids include gypsum pastes and printer inks. Mixtures and pastes were often concocted to whiten the face. Shampoos in the form of pastes or creams were formerly marketed in jars or tubes. Ointments may include ashes, clay, powdered sandalwood, or herbal pastes. Generally, liquid metal thermal pastes are used in such instances. Common pastes are curry pastes, fish pastes, some fruit preserves, legume pastes and nut pastes. Methyl cellulose is the main ingredient in many wallpaper pastes. Some rituals involve rice or other grains, seeds and pastes. There are, however, vegetarian red curry pastes available. Bovril and Marmite are food pastes with a distinctive flavour.