Silly String has been a common component of children's parties and general celebrations for more than 30 years. Despite its marketing to children and the festive ways in which it is employed, there are a few hidden dangers of Silly String that users should be aware of.
Silly string was patented in 1972 by the Wham-O company. Although two co-creators are listed on the patent (Robert Cox and Leonard Fish), many sources say that Julius Samann is the individual who should be credited with its discovery.
Silly String is a colorful liquid polymer resin that is contained under pressure within a can. Also in the can is a coolant, which serves as a propellant that shoots out a stream of resin when a button is depressed. The coolant quickly evaporates, and the liquid resin becomes solid--but still a bit sticky--nearly immediately.
Because the contents of Silly String are under pressure, they can potentially combust if placed near an open flame. The contents are also flammable as they exit the can. The coolant that propels the Silly String out of the can is very cold and capable of causing instant cold burn, or frostbite, if the nozzle is placed too close to the skin during use.
Silly String and similar compounds are bad for the environment. In the 1970s, the propellant in Silly String was a CFC compound, which has since been deemed to contribute to the destruction of the ozone layer and banned from use in the United States. These types of compounds have not been banned in other parts of the world, however, and other formulations of Silly String containing CFCs may possibly find their way onto shelves in the United States.
Silly String is essentially a plastic, and not biodegradable. It can get lodged in sewer systems and litter the streets for months. It is very sticky and difficult to clean from rough surfaces, such as brick and concrete. In fact, there are many cities in the United States that have banned the use of Silly String in public for these reasons.
Silly String and similar compounds have lately found another use. Soldiers in the Iraqi war spray it on surfaces when looking for trip wires. The Silly String will fall on the trip wires rather than the ground, revealing the dangerous traps.