General Advice for the Cleaning of Glassware

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Handle glassware carefully as most damage to laboratory glassware occurs during cleaning. Ensure that all safety precautions are taken when cleaning glassware including the wearing of eye protection and safety clothing where necessary.

Glassware should be washed as soon as possible after use to avoid caking of residue and it is important not to let soiled glassware dry out. If immediate cleaning is not possible, the glassware should be put to soak in water.

Hard utensils, wire brushes or bottle brushes with wire cores, should not be used for cleaning as they may scratch or score the surface of the glass causing weak spots in the glass. Scratched glassware is prone to breakage during freezing or heating. It is recommended that a sponge brush that is soft and flexible be used.

After washing, the glassware should be rinsed with tap water to remove any cleaning agent residue. After the tap water rinse, the glassware should be rinsed with distilled or deionized water.

Dry the glassware inverted on racks or pegboards. Inspect the glassware for chips, cracks and scratches on the inside and outside. Do not use glassware with visible signs of damage.

Cleaning of Glassware used with Common Laboratory Chemicals

Water soluble solutions (e.g. sodium chloride or sucrose solutions) - Rinse 3-4 times with deionized water.

Water Insoluble Solutions (e.g. solutions in hexane or chloroform) - Rinse 2-3 times with ethanol or acetone then rinse 3-4 times with deionized water. In some situations, other solvents need to be used for the initial rinse.

Strong acids (e.g. concentrated HCl or H2SO4) - Under the fume hood, carefully rinse the glassware with copious volumes of tap water. Rinse 3-4 times with deionized water.

Strong Bases (e.g. NaOH or concentrated NH4OH) - Under the fume hood, carefully rinse the glassware with copious volumes of tap water. Rinse 3-4 times with deionized water.

Weak acids (e.g. acetic acid solutions or dilutions of strong acids such as HCl or H2SO4) - Rinse 3-4 times with deionized water.

Weak bases (e.g. diluted NaOH and NH4OH) - Rinse thoroughly with tap water to remove the base, then rinse 3-4 times with deionized water.

For washing glassware used for organic chemistry - Rinse the glassware with the appropriate solvent. Use deionized water for water-soluble contents. Use ethanol for ethanol-soluble contents, followed by rinses in deionized water. Rinse with other solvents as needed, followed by ethanol and finally deionized water. If the glassware requires scrubbing, scrub with a non-abrasive brush using hot soapy water, rinse thoroughly with tap water, followed by rinses with deionized water.

Suggested Cleaning Procedure for Sintered Discs

Before first using glass filters with sintered disc, they should be cleaned with diluted, hot hydrochloric acid, followed by several rinses with distilled water.

Wash glassware as quickly as possible after use. During washing with water, all parts of the article should be scrubbed with a soft brush. Avoid any abrasion of the glassware. After cleaning thoroughly rinse with distilled water. Drying of the cleaned filters can be undertaken either in air or in a dry oven at temperatures not exceeding 100°C.

If after this cleaning procedure the sintered disc pores remain clogged, a more thorough chemical cleaning may be required.

Barium sulphateHot concentrated Sulphuric acid, Silver-chloride, Ammonia or Sodium hyposulfite
Copper/Iron OxidesHot Hydrochloride acid plus potassium chlorate
Mercury residueHot Nitric acid
Mercury sulphideHot aqua regia
AlbumenHot hydrochloric acid or hot ammonia
Grease, Oil, fatty materialsCarbon tetrachloride
Organic mattersHot concentrated cleaning solution, or hot concentrated sulfuric acid plus a few drops of sodium or potassium nitrite
GlucoseCarefully heat to approx. 200°C with mixed acid (5% H2SO4 and 1% HNO3)

Extensive rinsing of the filter with water must follow any use of the above-mentioned solvents.

Hot, concentrated phosphoric acid and hot alkaline solutions will attack the glass surface and they are unsuitable as cleaning agents. If they have to be filtered, an increase in sintered disc pore size and reduced life of the sintered disc is unavoidable.

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