Clean laboratory glassware ensures clear and reliable scientific results. As contaminants alter glassware volumes and add unexpected chemicals to experimental procedures, glassware cleaning becomes a top priority in any laboratory.
Precise and accurate experiments require glassware cleaned with a combination of physical and chemical cleaning methods. This protects experimental validity and protects users from unexpected reactions. Correct glassware cleaning, drying, and storage can even extend the equipments’ lifespan. In order to clean glassware correctly, a laboratory must use the correct procedure and the correct equipment.
Equipment to Clean Laboratory Glassware
As the glassware cleaning process often involves removing hazardous chemicals with other hazardous chemicals, personal protective equipment (PPE) helps the laboratory stay safe. This equipment, a staple of any laboratory environment, should involve gloves, goggles, lab coats, and aprons.
Laboratory glassware comes in various shapes and sizes, from small pipettes to large beakers and conical flasks. For clean glassware, laboratories, therefore, require various cleaning brushes. Manufacturers often recommend wooden or plastic handled brushes, as metal brushes may scratch the glass. These scratches create weak points in laboratory glassware, which could shatter or leak hazardous chemicals during an experiment.
Towels, Cotton, and Waxy Paper
After cleaning, laboratory glassware should be air-dried rather than towel dried. However, towels, cotton, and waxy paper prove helpful in the post-cleaning and storage stages. When air-drying, glassware should be rested upside-down on a clean towel. This lets the water run out while keeping the object’s mouth clean. In order to remain clean and contaminant-free, dry glassware should be plugged with cotton and wrapped in waxy paper. This protects the glassware from dust and other airborne contaminants.
Soap and water are essential components of any cleaning procedure. Laboratory glassware requires a detergent cleaning soap, preferably with anti-bacterial and mildly abrasive properties. As standard, laboratories should also mildly alkaline or acid solution (often 1% hydrochloric or nitric acid) to soak their glassware. Depending on the glassware’s previous reactants, they may use stronger chemicals such as piranha etch in extreme cases.
Laboratories involved in serology or other biohazardous experiments may also require sterilisation equipment such as an autoclave to clean laboratory glassware.
1. Initial Wash and Brush
Much like domestic washing-up, this first process involves simply emptying, brushing, and washing the glassware with detergents. Even new glassware may harbour dust or transportation contaminants, and the preliminary wash acts as the first line of defence against grease and other chemicals.
With glassware used in experiments, it’s often best to wash or soak them as soon as possible to prevent reactants hardening on the glass. Between each stage of the process, clean laboratory glassware should be rinsed and dried to remove cleaning products.
2. Soak in Clean Laboratory Glassware Solution
As some stubborn chemicals prove resistant to manual cleaning, laboratories soak their glassware in cleaning products for several hours to ensure full contaminant removal. Soaking time varies but can span to 12 hours or overnight. Some laboratories warm or boil their glassware in a cleaning solution. Others agitate the glassware carefully. These techniques help expedite the cleaning process and promote sterility. This soaking solution should be mildly acidic or alkaline in most cases.
However, as mentioned, laboratories with more stubborn or hazardous reactants use stronger cleaning chemicals. To ensure the laboratory remains safe as well as clean, carefully dispose of any hazardous cleaning products after use.
3. Final Wash and Brush
After the soaking process dissolves all the contaminants, wash the glassware with soap and water, then conduct several full rinses. This removes the cleaning products and any dissolved contaminants, alongside any grease. As contaminants and residue in poorly cleaned glassware can affect the meniscus, clean laboratory glassware becomes a must for accurate measurement. After another detergent wash, laboratories often use a program of several rinses, both with tap water and with distilled water. Implementing more than ten tap water rinses and more than one distilled water rinse ensures clean laboratory glassware. Hard water carries mineral ions and other contaminants. Therefore, distilled or double-distilled water improves the cleaning process.
Clean Laboratory Glassware Summary
As a final touch, observe the flow of distilled water over clean laboratory glassware to prove its cleanliness. Grease and imperfections, which may be otherwise invisible to the naked eye, cause patches and disturbances in the flow. Uninterrupted flow, therefore, proves that laboratory glassware is thoroughly cleaned and ready for drying and storage.