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.
