Page 134 - The Veterinary Laboratory and Field Manual 3rd Edition

The selection, use, maintenance and quality control of laboratory equipment and supplies 103

• Cleaning of glassware is always simplified • Do not use cleaning brushes that are so worn
by rinsing dirty glassware with water imme- that the spine hits the glass. Serious scratches
diately after use. If labware is not cleaned may be the result. Scratched glass is more
immediately, it may become impossible to prone to breaking during experiments. Any
remove the residue. mark in the uniform surface of glassware is a
• Brushes with wooden or plastic handles are potential breaking point, especially when the
recommended as they will not scratch or piece is heated.
abrade the glass surface. • Do not allow acid to come into contact with
• When washing, the water should be hot. a piece of glassware before the detergent (or
• During the washing, all parts of the glassware soap) is thoroughly removed. If this happens,
should be thoroughly scrubbed with a brush. a film of grease may be formed.
This means that a full set of brushes must • Grease is best removed by acetone.
be at hand – brushes to fit large and small
test tubes, burets, funnels, graduated cylin- Use of ultrasonic baths
ders and various sizes of flasks and bottles.
Motor driven revolving brushes are valuable An ultrasonic bath (Figure 2.70) is a metal ves-
when a large number of tubes or bottles are sel containing (mostly) water which produces
processed. high frequency sound waves. Contaminants are
literally ‘shaken off’ the glassware. It is used for
general cleaning, usually of small items, with
detergent additive (acid and alkali are not used
since these will attack the metal).

Cleaning method

Glass and plastic labware can be cleaned manu-
ally, in an immersion bath, in an ultrasonic bath
or in a laboratory washing machine.

• Manual cleaning, wiping and scrubbing
method: the generally accepted wiping and
scrubbing method with a cloth or sponge
soaked in cleaning solution is the most popu-
lar cleaning method. Labware must never be
treated with abrasive scouring agents or pads,
which might damage the surface. For gentle
treatment of labware, clean immediately after
use – at low temperatures, with brief soaking
times and at low alkalinity. Glass volumetric
instruments should not be exposed to pro-
longed immersion times in alkaline media
Figure 2.70 Ultrasonic bath. Photo: Willy above 70°C, as such treatment causes vol-
Schauwers, Provincial Institute for Hygiene, ume changes through glass corrosion, and
Antwerp, Belgium. destruction of graduations.

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