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COMMON OBSTINATE STAINS
The most common stains and dirt on laboratory apparatus include;
(a) Oils and Grease stains
Clean using a more efficient cleaning liquid mixed with concentrated sulfuric acid and fuming nitric acid in equal proportions. Alternatively, it can be removed by filling with warm soapy water and leaving for 15 min thenrinsing with water followed by concentrated HCl and finally with distilled water .
(b) Tar stains
These can be cleaned using benzene or any other suitable solvents followed by cleaning with any abrasive powder.
(c) Carbon stains
Clean using small volumes of chromic acids and then heat gently and evenly on a flame until the acid begins to fume.
(d) Blood stains
Clean by soaking or applying hydrogen peroxide directly to the stain. After the stain is removed, rinse the area with cold water to remove any peroxide that may be left behind
(e) Microbial stains
Clean by sterilizing in an autoclave or use appropriate disinfectant