Explanatory notes
… aldehydes (formaldehyde, furfuraldehyde, etc.). The most important are urea resins (for example, urea‑formaldehyde), … or not modified with oils, fatty acids, alcohols, or other synthetic polymers) they are employed as glues and as … an opaque, dark brown to clear, light brown liquid and is synthesised by reaction of aniline and formaldehyde to form …