Uses
Formaldehyde kills most bacteria, and so a solution of formaldehyde in water is commonly used as a disinfectant. When he arrives at his room in the tuberculosis sanatorium in Thomas Mann's The
Magic Mountain, Hans Castorp is told: "An
American woman died here day before yesterday. . . . After they took her away of course they fumigated the room thoroughly with formalin, which is the proper thing to use in such cases" {1924; trans. H. T. Lowe-Porter {1927).
It is also used to preserve biological specimens, and as a
preservative in
vaccinations. In medicine, formaldehyde solutions are applied topically to dry the skin, such as in the treatment of warts. Formaldehyde based solutions are used in embalming to disinfect and temporarily preserve human remains pending final
disposition.
Most formaldehyde, however, is used in the production of polymers and other chemicals. When combined with phenol, urea, or melamine, formaldehyde produces a hard thermoset resin. These resins are commonly used in permanent adhesives, such as those used in plywood or carpeting; and as the wet-strength resin added to sanitary paper products such as (listed in increasing concentrations injected into the paper machine headstock chest) facial tissue, table napkins, and roll towels. They are also foamed to make insulation, or cast into molded products. Production of formaldehyde resins accounts for more than half of formaldehyde consumption.
Formaldehyde is still used in low concentrations for process C-41 (color negative film) stabilizer in the final wash step, as well as in the process E-6 pre-bleach step, to obviate the need for it in the final wash.
Formaldehyde is also used to make numerous other chemicals, used even in personal care products such as toothpaste. Many of these are polyfunctional alcohols such as pentaerythritol, which is used to make paints and
explosives. Other formaldehyde
derivatives include methylene diphenyl diisocyanate, an important component in polyurethane paints and foams, and hexamine, which is used in phenol-formaldehyde resins and to make the explosive RDX.
Formaldehyde cross links amino groups.
