0
A TECHNIQUE FOR SAFE HANDLING OF HAZARDOUS MATERIALS IN GLASSWARE R. L. RAY Ethyl Coqoration, Baton Rouge, Louisiana
As THE experimental
research laboratories of today expand into new fields, more and more hazardous materials are made and handled by the chemist. Some of these materials are highly toxic, some spontaneously ignite in air, and some react vigorously-sometimes even exploding upon shock. The chemist u-bo handles these materials in fragile containers exposes himself to possible serious injury-perhaps fatal injury-and he endangers those around him and risks the possible loss of vital and expensive equipment. In the researrh laboratories of Ethyl Corporation, a method of protection has been incorporated which has given the chemist the utmost confidence and safety in handling such materials. Glassware used in ex~eriments where hazardous materials are employed is coated with a flexible vinyl film. This vinyl film consists of a plastisol type PVC resin mixed nith a plasticizer and stabilizer to form a paste which is then applied to the glass~rare by dipping, spraying, or ,'painting." The paste is then fused into a clear, tough, flexible film by heating either ~ i t ah flame or in a, convection oven. This plastic coating absorbs shock, prevents the scattering of glass particles in the event of an explosion, and confines the material within the film upon the
r
248
~
~ ~ i~ h consnea i. b ~ the ~ contents in ~~~k~~ n a a k
breahge of the glass. Vision is not hindered by the use of this film because the plastic coat is essendially optically clear. Single objects, such s' flssks, can be easily coated in just a few minutes; complex systems such as a complete apparatus setup can be coated, including joint to joint seals, with the same ease as a single object. Upon completing an experiment,, the coating can be easily stripped off and disposed of. In cases of additions to an apparatus setup or the repair of a break in the film,the plastisol paste can be applied over the existing film and the two layers fused together r\-ith satisfactory results. A t ". v ~ i c a lrecine used on elasmare a t Ethvl Corporation is as foilows: u
100 grams of a plastisd type PVC resin 6C-i0 grams of plasticizer ( i s . , dioctyl phthalate) 3 erams stabilizer (i.e.. . ,oreano - tin tvnesl
-
.A
.
The above ingredients, all of which are commercially available, are mixed together either by hand or by a kitchen mixer into a smooth,, free-flowing paste. To eliminate the entrapped air in the paste, the paste can be poured in a thin stream from one container into another several times. When applying the paste to an object by dipping, a film of a fraction of a mil to 30 mil can be deposited depending upon t,he draining time and the rate of drawing the object out of the paste. When the desired thickness is obtained, the object may be fused in an oven a t 300"40O0F. for approximately 8-15 minutes, depending on the temperature. After the object has cooled, the above procedure mill result in a tough, clear film enclosing the object. If the paste is to be fused by the use of a flame, care must be taken not to overheat any one area or "burn" the surface because of possible development of weak spots in the film. For best results, use a wide flame held 3-5 inches from the surface. The accompanying illustration shows the advantage of the protective plastic coating when a flask was dropped on a concrete floor. The flask had been coated with the above formula and fused in an oven at 350°F. for 10 minutes with excellent results.
JOURNAL OF CHEMICAL EDUCATION
