Safe handling of Laboratory Glassware

Common laboratory glassware

Glassware is the most common commodity in a laboratory. Laboratory glassware is a lot different from kitchen glassware used in households as it is designed for special purposes and requires delicate handling. It is important to bear in mind that laboratory glassware is to be used exclusively for laboratory applications and should not be taken out for general usage.

The suggestions offered in the article are not one time suggestions but should be imbibed right from your school days. These suggestions are provided under different laboratory operations but it is advised that if any damage is noticed like cracks or chipping then such items should be discarded to avoid harm in future use.

Heating

Glass is brittle in nature and is not a good conductor of heat. It can break or crack if subjected to sudden thermal shocks. Heat should be evenly distributed when boiling liquids. A ceramic coated wire mesh should be used in open flame heating or when a hot plate is used it should have a larger base than the boiling vessel. On removal the hot flask should be clamped properly to a stand and should not be kept on a wet workbench or allowed to come in contact with any liquid spill.

Whenever heating is done in a hot air oven remove stoppers, if any, and ensure that there are no cracks or scratches on the glassware. Use heat proof gloves or mittens for removal of glassware from hot air ovens. Allow the items to cool naturally before further use.

When boiling make use of glass beads or glass wool to prevent bumping of boiling liquid and never look down from top when a liquid is boiling.

Stirring

Stirring is essential for homogenization of solutions. Make use of a teflon- coated magnetic stirrer bead or a mechanical shaker, if available. In absence of such devices a glass rod can be used but take care to ensure that stirring is carried out gently. Brisk stirring can result in breakage or if the speed of rotation of magnetic stirrer is kept high it can result in creation of a vortex leading to spillages.

Washing

Cleaning should be done using a mild detergent solution. A soft brush can be used to assist the cleaning but a hard bristle brush or one with worn out bristles can result in abrasions and scratches. When immediate cleaning after use is not possible at least soak the used glassware in water for some time before final cleaning. Grease can be removed by making use of a dilute sodium bicarbonate solution or acetone. Stubborn deposits can be removed using potassium dichromate solution or nitric acid but adequate precautions in handling such solutions are necessary. Keep in mind that hydrofluoric acid should never be used for glassware cleaning.

Automated washing machines should be preferred when bulk quantities are required to be washed. They help save time and depending on requirements washing cycles can be selected.

Carriage & Storage

Large bottles, volumetric flasks and Winchesters should be carried using both hands. One hand should hold the neck and the other should support the bottom. A tray should be used for transfer of number of volumetric flasks for dilution purposes. Sidewall storage shelves for reagents and chemicals should be affixed at appropriate height so that removal of corrosive liquids should not result in overhead spillage accidents.

Tube insertion and removal from bungs

Wet the glass tubing or rod with water or glycerol when inserting or removing from a bung. A dry tube can break during the process and result in injuries. Special care is often faced in removal of thermometers. A better option is to cut the bung when removing the thermometer.

Joining of glass components

Burettes and distillation columns are normally provided with ground glass joints which help in leak proofing when a thin grease film is applied to such joints. When not in use a thin paper strip can be inserted to prevent jamming of joints. Stuck joints should be opened with great care to avoid breakages. Gentle tapping against a wooden surface or applying thin oil to joint or dipping in acetone helps loosen such joints.

Vacuum applications

Rotary vacuum evaporators require heating of liquid mixtures under reduced .Make use of screen shields or apply tape to the round bottom flask to lessen damage due to accidental breakages. The prescribed vacuum limits should also not be exceeded.

Centrifugation

Carelessness in using centrifuges often results in breakages when centrifuges are in motion. Always balance the sample tubes with counter balancing tubes at opposite ends and these should be filled with blank solution to same levels. Further the speed of centrifugation should not be allowed to exceed the permitted levels.

In conclusion laboratory glassware should be used for the designated purpose only. In no case should such glassware be used for serving of beverages or other food items as this can lead to serious harm through contamination from laboratory chemicals.