An Inexpensive Safety Shield from a Plastic Water Jug John J. Fortman Wright State University, Dayton, OH 45435 Current national and state regulations greatly restrict what chemistry can be done in high school and junior high science courses. Understandably, this is to assure the safest nrocedures nossible in the o ~ e r a t i o nof laboratories and the presentation of demonstration experiments. A teacher's concern should be for the ereatest possible safety for their students with or without such regdations. ~ o w i v e rgood , science teachers recoenize that science should be experienced and not just leained from verbal and written presentstions. Even pictures and videos lack the personal involvement and interest generated through live presentations. A problem is that even many relatively safe chemical reactions should he .--. - - done behind a saferv shield and safetv shields are generally so expensive as to 6e beyond the avkrage school hudeet. ~ r t h o u the ~ h shield described in this paper will not meet the strictest safetv standards reauired for the most violent reactions, i t is a reasonable safeguard against the splattering of acids, bases, and organic liquids and the scattering of relatively soft solids like pieces of sodium or polyethylene fraements. I t would also slow down or deflect harder fragments such as glass from broken equipment. At least in most cases it is better than thechoice between doingademonstration with no protection a t all or not doing a meaningful and stimulating demonstration such as the addition of sodium to water, or some alcohol or hydrogen explosions in soft containers. I t can also act as a fire screen although i t will itself melt. Its bieeest advantaee is that i t can be made i n e x ~ e n &ely fromEeadily available object without too much effort or skill. Thus there is no excuse for not havineand usinr! one. The required starting object is simply a plastic 5-galwater iue. -. such as those in which distilled water may be purchased. Using a hacksaw, jigsaw, or saber saw, the top &d back are cut off as illustrated in the figure. The cut must he started ~~~~
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along a curved edge in order to open a large enough hole to allow the saw blade to be inserted through the jug's wall. Safety glasses should be worn to protect your eyes from plastic cuttings. I t is difficult to hold the jug steady during the cutting, particularly if you are using an electric saw, so it may be necessary to have a second person bold the jug down, or to wedge it into a corner for stability. I t is not possible for the author to take responsibility for accidents that might occur using the shield, and good judgement in its use is a must. Before using the shield in class, it would be prudent to test the shield aeainst materials or chemical sdutions that might be splatte;ed in a demonstration to find out how resistant the plastic is to them. Acknowledgment The author is grateful to Jim Arehart and his co-workers in the Instrument and Machine Shop a t Wright State for exploring the best procedure for making these shields.
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234
Journal of Chemical Education
Diagram for cuning a safety shield out of a water jug.
