|Current supplier||S. C. Johnson & Son|
Crystal Drano 
||This article needs attention from an expert on the subject. (January 2012)|
The colored crystals in Drano are for appearance only; lye is white in color. Lye decomposes most organic matter and is particularly effective on fat, grease and hair which are materials which often clog drains. As the decomposition is more rapid if the temperature of the mixture is higher, and lye reacting with aluminum produces heat, shards of aluminum are an ingredient in Drano. Several chemical reactions take place here:
- When Drano is added to water, the sodium hydroxide, sodium nitrate, and sodium chloride dissolve. The heat of solution liberated when sodium hydroxide is dissolved warms the mixture. (The result of lye reacting with fat is a kind of soap, sodium stearate, the same soap that was commonly made at home and also manufactured commercially in the 18th and 19th centuries.)
- The formula for the lye reacting with the aluminum shards is 2NaOH + 2Al + 2H2O → 3H2 + 2NaAlO2, although the exact species in solution may be NaAl(OH)4. The reaction can raise the temperature sufficiently to cause the mixture to boil. The reaction also liberates hydrogen gas which churns the mixture and improves the interaction between the lye and the materials clogging the drain. While the position of the mixture in the drain pipe usually does not result in high pressure developing from the liberated hydrogen or the boiling of the mixture, it is possible for the mixture to spurt out of the drain so the user must exercise care when using Drano.
- The sodium nitrate "absorbs" the hydrogen, reducing the fire and explosion hazard posed by free hydrogen gas. Hydrogen combines with the nitrate ion, producing ammonia, which also decomposes organic material although not as aggressively as lye does. The reaction is: 2NO3− + 9H2 → 2NH3 + 6H2O.
For years, Drackett advertised Once every week, Drano in every drain. Various mixes of relatively non-toxic solvents are now sold commercially for the purpose.
Other Drano products 
Drano Aerosol Plunger was developed in the late 1960s, intended as a safer product that would be kinder environmentally. It was basically just a can of CFC propellant, the best-known brand of which was Freon. After Earth Day in 1970, there came increasing pressure to eliminate CFC propellants. Drackett used cheaper propellants, a blend of propane and butane, in all its other products. However, the propellant mix created a fire hazard.
The product was problematic. The forceful propellant required most consumers use both hands to control the can, plus another hand or two to hold a rag over the drain vent to contain the pressure. The pressure sometimes knocked apart poor plumbing without blasting free the clog. Consumers who ignored instructions and attempted to use chemical drain openers first could be chemically burned from blow-back.
Liquid Drano was introduced in response to Clorox's purchase of Liquid-Plumr in 1969. Originally, it was simply a liquid lye (sodium hydroxide). In the late 1970s, the product was reformulated as a combination of liquid lye and sodium hypochlorite. Sodium hypochlorite is sold in 5% concentration as laundry bleach and in 10% concentration as a swimming pool disinfectant.
See also 
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth–Heinemann. ISBN 0080379419.
- Gallery of classic graphic design featuring Drano.