Successful experimental results can only be achieved by using a clean apparatus. In all instances laboratory glassware

must be physically clean, in nearly all cases it must be chemically clean and in specific cases it must be bacteriologically clean or sterile. There must be no trace of grease and the safest criteria of cleanliness is the uniform wetting of the glass surface by distilled water - this being of the utmost importance for glassware used for volumetric methods. Any prevention of uniform wetting of the surface will introduce errors such as distortion of the meniscus and accuracy of volume


  • Cleaning of glassware which has contained hazardous material must be solely undertaken by experienced personnel
  • Most new glassware is slightly alkaline in reaction. For precision chemical tests, new glassware should be soaked several hours in acid water (1% solution hydrochloric acid or nitric acid) before washing
  • Glassware which is contaminated with blood clots, culture media, etc., must be sterilized before cleaning If glassware becomes unduly clouded or dirty or contains coagulated organic matter, it must be cleaned with chromic acid cleaning solution. The dichromates should be handled with extreme care because it is a powerful corrosive
  • Wash glassware as quickly as possible after use but if delays are unavoidable, the articles should be allowed to soak in water
  • Grease is removed by weak sodium carbonate solution or acetone or fat solvents. Never use strong alkalis
  • Hot water with recommended detergents should be used and if glass is exceptionally dirty a cleaning powder with a mild abrasive action can be applied provided the surface is not scratched
  • During the washing all parts of the article should be thoroughly scrubbed with a brush selected for the shape and size of the glassware. Brushes should always be in good condition to avoid any abrasion of the glassware
  • When chromic acid solution is used, the item may be rinsed with the cleaning solution or it may be filled and allowed to stand - the amount of time depending on amount of contamination of the glassware
  • Special types of precipitate material may require removal with nitric acid, aqua regia or fuming sulphuric acid. These are very corrosive substances and should be used only when required
  • It is imperative that all soap detergents and other cleaning fluids be removed from glassware before use. This is especially important with the detergents, slight traces of which will interfere with serologic and culture reactions. After cleaning, thoroughly rinse with tap water ensuring that containers are partly filled with water, shaken and emptied several times. Finally rinse with deionised or distilled water
  • Drying can be undertaken either in baskets or on pegs    in air or at a temperature not exceeding 120º C.
  • Always protects clean glassware from dust by use of   temporary closures or by placing in a dustfree cabinet.