ARLINGTON, Va.—November 4, 2015—Responding to serious safety issues surrounding science experiments and demonstrations involving ignition of flammable liquids, the National Science Teachers Association (NSTA) strongly recommends that teachers immediately halt the use of methanol-based flame tests on an open laboratory desk.
When carried out on open laboratory desks (outside of a chemical hood) these demonstrations present a high risk level for flash fires and deflagrations that can cause series injuries to students and teachers. On an open laboratory desk, invisible flammable vapors can be ignited by a flame, a spark (including static electricity), or a hot surface. Teachers who conduct these types of demonstrations outside of a fume hood put themselves and their students at unnecessary and serious risk during this demonstration.
Teachers need to seek out safer alternative laboratory investigations and demonstrations that minimize and reduce potential injury to students and teachers. In order to select safer alternatives, teachers need to have a thorough and current understanding of safer laboratory practices and perform hazards analyses and risks assessments of science investigations prior to conducting them.
If demonstrations involving methanol-based flame tests are to be done, they should be handled only under a fume hood. This, however, still presents some level of risk. Safer alternatives to using flammable liquids for flame tests are available and should be considered to make it as safe as possible for students and teachers. Appropriate resources such as safety data sheets also need to be reviewed as part of the hazards analyses. Media reports have drawn attention to injuries that have occurred to students and teachers when methanol is ignited to show how different substances produce flames of different colors based on their varying properties. The experiment, referred to as the “rainbow” demonstration, is visually exciting but dangerous when conducted outside a fume hood.