Even the most carefully executed experiment can give erroneous results if dirty glassware is bought to use. If the glassware that is used for measuring liquids is contaminated with grease and other materials, it prevents the glass from being uniformly wetted. This in turn will affect the volume of liquid delivered and the amount of residue adhering to the walls of the container. Likewise, presence of impurities in glass labware can distort the meniscus and can prevent one from getting the correct results out of the science lab experiment.
Keeping the laboratory glassware physically neat and clean, free of grease, and bacteria is therefore of the utmost importance.
A. To keep your glass labware neat and clean, you must wash it immediately after use. Put glassware in water if you cannot clean it immediately otherwise the residue will stick to the labware and it would get difficult to remove it.
B. For washing the glass labware, make use of soap, detergent, or cleaning powder. Try to use soap and cleaning powder without any abrasives as it can scratch the glass. However, for glassware that is too dirty, you can make use of cleaning powder with mild abrasive action to get good cleaning results. Chromic acid solution is quite effective in cleaning unduly clouded or dirty glassware. For scrubbing the glassware thoroughly, you must use a brush.
C. After cleaning, rinse the glassware with tap water. Allow the water to run into and over the glassware and then fill each piece with water. Fill test tubes, flasks, and other glassware with water and shake and empty them. Do this for at least 5-6 times to clean the glassware properly. For cleaning contaminated glassware, you will have to sterilize them too.
D. Washed labware must either be placed in a basket with their mouth downwards for allowing them to dry completely or they should be made to dry in an oven. You can also hang test tubes, flasks, and other labware on wooden pegs for drying them out. Stand dry cylinders, burets, and pipets on a towel for drying them properly.
E. Place clean glassware in a cabinet to protect it from dust. You can also make use of cotton, or cork, or can tape a piece of paper on the mouth of the glassware to prevent dirt and dust from entering the glassware. Keep washed, cleaned, and sterilized glassware pieces in special racks and at a distance to avoid any breakage.
With proper care and maintenance you can not only increase the life of your labware, but can also enhance your lab safety.
- Before using any piece of glassware, always take time to examine it carefully and ensure that it is in good condition. Do not use any glassware that is scratched, chipped, cracked or etched. Defects like these can seriously weaken the mechanical strength of the glass and cause it to break in use.
- Dispose of broken or defective glassware safely. Use a purpose-designed disposal bin that is puncture resistant and clearly labelled. Pyrex glassware (or any other borosilicate glass) should under no circumstances be disposed of in a domestic glass recycling stream (e.g. bottle banks), as its high melting point makes it incompatible with other glass (soda-lime glass) for recycling. The correct method of disposal is to include it in the general waste in accordance with the relevant guidelines, provided that the glass is free from any harmful chemical contamination.
- Never use excessive force to fit rubber bungs into the neck of a piece of glassware. Always ensure that you select the correct size of bung.
- Many Pyrex or Quickfit glass products are supplied with durable, easy to use plastic screw thread tubing connectors to allow the safe fitting of any flexible tubing. When attaching tubing, ensure that the screw thread connector is removed from the glassware, the tubing is lubricated and protective gloves are worn. Never use excessive force to connect the rubber hose or tubing.
- Carrying or lifting large glass flasks, beakers or bottles, etc. by the neck or rim can be very dangerous. Always provide support from the base and sides.
- When stirring solutions in glass vessels, avoid using stirring rods with sharp ends which can scratch the glassware causing it to become weakened.
Posted by Owolabi Hakeem