Steps involve in cleaning - � a)Soda lime glass � b)Borosil glass

Soda Lime Glasses

• Soda-lime glass, also called soda-lime-silica glass.
• Most commonly available and largely manufactured glass.
• Composed of roughly 70% Silica or Silicon Dioxide, 15% Soda or Sodium Oxide and 9% lime, also known as Calcium Oxide.
• It is capable of being re-softened a number of times if needed, to manufacture and finish a product. This makes it versatile and suitable for diverse applications.

Soda Lime Glassware

•  The method includes cleaning the SLG substrate using an alkali cleaning solution.
• The alkali cleaning solution includes an alkali material having a concentration of about 1% to about 25%. The alkali material may include at least one of potassium hydroxide (KOH) and sodium hydroxide (NaOH).

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Soda Lime Glass Properties�

1. It’s cheap.
2. It’s chemically stable.
3. It’s hard. 
4. It’s workable. 
5. It’s vulnerable to thermal shocks.
6. It’s an electrical insulator.
7. It transmits visible light. 

Steps involve in cleaning Soda lime glass �

• 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 brush using hot soapy water, rinse thoroughly with tap water, followed by rinses with deionized water.

Borosilicate glass

• Borosilicate glass is a type of glass with silica and boron trioxide as the main glass forming constituents.
• Borosilicate glasses are known for having very low coefficients of thermal expansion , making them more resistant to thermal shock than any other common glass. Such glass is subjected to less thermal stress and can withstand temperature differentials without fracturing of about 165 °C (329 °F).
• It is commonly used for the construction of reagent bottles and flasks.

Borosilicate glass Properties

1. Very low thermal expansion co-efficient.
2. High softening point.
3. Resistant to thermal shock.
4. Chemically resistant.

Steps involve in cleaning Borosilicate glass

• Don't bump your borosilicate glassware against a sink wall or against other vessels during cleaning. You could damage the vessel, even subtly, and progressive damage reduces the life of the vessel and introduces safety hazards.
•  Do use a soft bristle brush with a plastic or wooden handle when cleaning borosilicate glassware. This will reduce scratching and unnecessary abrasions.
•  Don't use hydrofluoric acid or strong alkali soaps or acids to clean borosilicate glassware. Hydrofluoric acid is highly corrosive to borosilicate glass, and strong alkali soaps / acids are also damaging.
•  Do use Alconox™ or similar detergents to clean borosilicate glass.
•  Do rinse with distilled water.

WHAT’S THE DIFFERENCE BETWEEN �BOROSILICATE GLASS �AND� SODA-LIME GLASS?

• The main difference between soda-lime glass and borosilicate glass is their silicon dioxide and boron trioxide content.
• Soda-lime glass typically contains 69 per cent silicon dioxide compared to 80.6 for borosilicate glass. It also contains far less boron trioxide: just 1 per cent compared to 13 per cent in borosilicate

WHY BOROSILICATE GLASS IS MORE IMPORTANT THAN SODA-LIME GLASS?�

1. Borosilicate Glass is Mechanically Stronger & Harder than Soda Lime
2. Borosilicate Glass is Much More Resistant to Thermal Shock.
3. Borosilicate Glass Can be Shaped Into Vacuum Insulated Vessels
4. Borosilicate Glass Is More Chemically Resistant to Acids.

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Chromic acid solution

• Chromic acid is usually used for a mixture made by adding concentrated sulfuric acid to a dichromate, which may contain a variety of compounds, including solid chromium trioxide.
• Chromic Acid is also called Tetraoxochromic acid.
• It can be used to clean laboratory glassware with Stubborn organic stains. Chromo sulfuric acid or Sulfochromic mixture is a strong oxidizing agent that is used to clean laboratory glassware.

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Preparation of Chromic acid solution

1. Place a clean, glass liter beaker in a glass pan to prevent damage from accidental spills.
2. Wearing rubber gloves, put 20 g of powdered sodium dichromate into the liter glass beaker.
3. Mix in a small amount of water to form a paste, and stir thoroughly with a glass stirring rod.
4. Continue to stir the mixture while slowly adding 300 ml of concentrated sulfuric acid to the beaker.
5. Carefully pour the solution from the beaker into a glass bottle with a stopper on top.

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Storage of solutions

• Label all chemical containers fully. We recommend including the owner’s or user’s name along with the date received.
• Provide a specific storage space for each chemical, and ensure return after each use.
• Store volatile toxics and odoriferous chemicals in ventilated cabinets. Please check with your environmental health and safety personnel for specific guidance.
• Store flammable liquids in approved flammable liquid storage cabinets. Small amounts of flammable liquids may be stored in the open room. Check with your local authority (e.g., fire marshal, EH&S personnel) for allowable limits.
• Separate all chemicals, especially liquids, according to compatible groups. Follow all precautions regarding storage of incompatible materials. Post a chemical compatibility chart for reference, both in the lab and next to chemical storage rooms. �

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Continue..

• Use appropriate resistant secondary containers for corrosive materials. This protects the cabinets and will catch any leaks or spills due to breakage.
• Seal containers tightly to prevent the escape of vapors.
• Use designated refrigerators for storing chemicals. Label these refrigerators CHEMICAL STORAGE ONLY—NO FOOD.
• Never store flammable liquids in a refrigerator unless it is specifically designed and approved for such storage. Use only explosion-proof (spark-free) refrigerators for storing flammables.

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