Care Maintenance

Safe use of Glassware

When heated properly, glassware will provide long-lasting and easy service. The following notes will help users get the most life and performance out of their glassware.
Glass may suffer damage in three ways
  • It may fail under heat stress in the 'steady state'.
  • It may break when quickly heated or chilled.
  • Glass, if heated over a particular temperature, may develop a persistent tension upon cooling, failing.
The following suggestions will help in avoiding failures during heating and cooling procedures
  • Never leave the evaporation vessel unattended. To avoid dryness, reduce the temperature gradually as the liquid level declines; otherwise, the glass vessel may fracture or explode.
  • When placing a warm vessel on a cold or moist surface, exercise extreme caution. The vessel may break due to sudden temperature changes.
  • To avoid thermal fracture, cool vessels slowly and gradually.
  • Heat should never be applied to a badly damaged or etched vase to avoid shattering.
  • Avoid using a point source of heating in a vessel and instead diffuse it with a metal gauge or air/water bath. Alternatively, guarantee even heating of the vessel by slowly moving it in reference to the heat source.
  • Some chemical processes require uniform heat. For this, regulate the large soft flame of the Bunsen burner to heat slowly yet uniformly.
  • To avoid breaking the vessel, adjust the flame contacts and heat it below the liquid level.
  • When quick heating of the vessel and its contents is required, employ anti-bumping devices such as pumice or glass wool to prevent interior abrasions.
  • Thick-walled glassware should be heated with an electric immersion heater rather than a direct flame or another localized heat source.
  • To reduce localized stress and the risk of breakage, do not heat glassware on electric heaters with open elements.
  • To avoid uneven heating and glassware breakage, always make sure that the hot plate's surface is larger than the base of the vessel being heated.
  • When utilizing electrical appliances, always adhere to the manufacturer's recommendations.

Mixing and Stirring

  • When utilizing a glass vessel with a magnetic stirrer, always use a covered follower to avoid abrading the interior of the vessel.
  • Before using a glass or metal mechanical stirrer in a glass vessel, calculate the stirrer's height to ensure that the stirrer blades do not touch the vessel's bottom or sides.

Vacuum and Pressure

  • When working with pressured or vacuumed glassware, always follow safety precautions.
  • Never use glasses beyond the recommended safety limit.
  • Positive and negative pressures should be applied and released gradually, and pressure shifts should never occur suddenly.

Personal Safety

  • To prevent errors, use tongs or asbestos gloves to remove any glassware from the heat source.
  • Follow safety precautions.
  • Before opening an acid bottle, always flush the outside with water.
  • All mercury jars should be well-stopped. Mercury toxicity is cumulative, and the element's tendency to combine with a variety of metals is well recognized.
  • Never use taste or smell to identify chemicals, and never drink from a beaker.
  • Label every jar before filling. Never fill or dispose of contents in unmarked containers.
  • When clamping glassware, prevent glass-to-metal contact and do not overtighten the clamps to avoid shattering.
  • Splattering from acids, caustic chemicals, and strong oxidizing solutions on the skin or clothing should be washed away quickly with plenty of water.
  • When working with chlorine, hydrogen, sulfide, carbon monoxide, hydrogen cyanide, and other very hazardous compounds, always wear a protective mask or conduct your research in a well-ventilated location under a fume hood.
  • When working with volatile materials, keep in mind that heat produces expansion, and the containment of expansion leads to explosion.
  • Perchloric acid is particularly harmful since it explodes when in contact with organic molecules. Avoid using perchloric acid around wooden benches or tables. Perchloric acid bottles should be stored on glass or ceramic trays with adequate volume to hold all of the acid in case the bottle breaks. When handling perchloric acid, always wear protective clothes.
  • When using hot plates or other electrical equipment, make sure the wires and plugs are in good condition. Never handle an electrical connection with moist hands.


Clean equipment is required for successful experimental findings. Laboratory glassware must always be physically clean, almost always chemically clean, and in some situations bacteriologically clean or sterile. There must be no traces of grease, and the safest cleanliness criterion is consistent wetting of the glass surface with distilled water. Any method that prevents consistent wetting of the surface can create defects such as meniscus distortion and volume accuracy.

General Cleaning

  • Experienced personnel must only attempt. Cleaning glassware that contains hazardous compounds.
  • Most new glassware has a little acid reaction. Before washing new glassware, soak it in acid water (1% solution hydrochloric acid or nitric acid) for several hours to ensure accurate chemical tests.
  • Glassware that has been contaminated with blood clots, culture medium, or other substances must be sterilized before cleaning.
  • If glassware gets very cloudy or unclean, or if it includes coagulated organic matter, it must be cleaned with a chromic acid cleaning solution. Dichromates should be handled with extreme caution because they are highly caustic.
  • Wash glassware as soon as possible after use; however, if delays are inevitable, leave the objects to soak in water.
  • Grease is removed with a mild sodium carbonate solution, acetone, or fat solvents. Never use powerful alkalis.
  • Hot water with specified detergents should be used, and if the glass is extremely unclean, a cleaning powder with a light abrasive effect can be applied as long as the surface is not harmed.
  • During washing, all sections of the piece should be carefully washed with a brush appropriate for the shape and size of the glassware. Brushes should always be in good condition to prevent abrasion of glassware.
  • When using chromic acid solution, the item can be rinsed with the cleaning solution or filled and allowed to stand for the appropriate amount of time, depending on the level of pollution on the glassware.
  • Special precipitate materials may need to be removed with nitric acid, aqua regia, or fuming sulfuric acid. These are extremely caustic compounds and should only be used as needed.
  • All soap detergents and other cleaning solutions must be removed from glassware before use. This is especially critical for detergents, as even small amounts can interfere with serological and cultural reactions. After cleaning, fully rinse with tap water, making sure the containers are partially filled, shaken, and emptied multiple times. Finally, rinse with clean or distilled water.
  • Drying can be done in baskets or on pegs in the air or at temperatures no higher than 120 OC.
  • Always keep clean glassware away from dust by using temporary closures or storing it in a dust-free cabinet.