Glassware is used to store, mix, measure, deliver, and store biological and chemical substances or reactions in laboratories.
Since glass is inert, chemically neutral, and heat-resistant, lab glassware does not interact with the chemicals and can withstand high temperatures. Most glassware in the lab is colorless and transparent, allowing users to observe the substance or its transformation in the glassware.
However, Amber glassware are brown (not transparent) and used to store and handle light-sensitive chemicals or reactions. The amber-brown color limits the light from the surrounding, preventing unwanted decay or interference.
Types of Glasses for Lab Glassware
Glassware found in most laboratories can be classified based on its composition:
1. Borosilicate Glass
Also referred to as Type I lab glassware, borosilicate glasses are the most common type of glassware in most laboratories. It is primarily composed of silica and boric oxide, and the glass is known for durability, corrosion resistance, and non-reactivity to most acids and bases.
Borosilicate glassware is resistant to high temperature, pressure, and thermal expansion, allowing the lab glassware to be sterilized by autoclaving, which is performed under high pressure and temperature, in addition to chemical sterilization.
2. Soda-lime Glass
Type II or soda-lime glasses contain alkali earth, such as calcium oxide, magnesium oxide, and silica oxide. They are chemically inert and durable but generally less resistant to high temperatures than borosilicate glass. Thus, contaminated soda-lime glassware cannot be decontaminated by autoclaving like borosilicate glassware.
3. Quartz Glass
Quartz glass comprises silica with little impurities from other elements. It possesses good elasticity, high resistivity, low thermal conductivity, and compressive strength. The glass can be shaped and molded into various forms.
Nonetheless, glassware made from quartz is the most expensive glassware in laboratories. It is lightweight and should not be sterilized by autoclaving or cleaned in a dishwasher. Instead, quartz glassware should be wiped and rinsed with deionized water or soaked in mild detergent before rinsing several times with deionized water.
Check out our complete guide on lab glassware’s physical and chemical properties to learn more about glassware.
Common Types of Lab Glassware
Glassware is shaped and designed for specific use in laboratories. Volumetric or graduated glassware is intended for measuring and delivering liquids, while others are used to transfer, incubate, store and mix chemicals.
Common glassware found in laboratories are:
Beakers are flat-bottom cylindrical containers for transferring liquids, mixing, and heating samples. Beakers can accommodate solid and liquid samples ranging from 10mL to 5L. They have a graduated scale that indicates the volume of the sample. However, beakers have low accuracy – even graduated ones are prone to ±5% error.
Flasks are containers with wide bottoms and narrow mouths, which can be closed by rubber or cork stoppers. They are used for mixing, heating, and boiling liquid samples.
- Erlenmeyer flasks, also known as conical flasks, are general-purpose glassware used with magnetic stirring bars to mix and heat samples.
- Filtering flasks are flasks with a tube connected to a conical part near the mouth of the flask. This tube is connected to a vacuum source, creating a vacuum inside the flasks. When used with a Büchner funnel on the top of the flask, the vacuum inside the flask will speed up the filtration process.
- Boiling flasks are specifically designed for lab works that involve vigorous boiling, such as distillation and refluxing. They can be broadly classified into:
- Florence flasks are boiling flasks with flat bottoms and round bodies often used when the flasks are heated on a flat surface.
- Round bottom flasks, also called RB flasks, are boiling flasks with round bottoms and bodies. They are used with laboratory stands and clamps, which hold them in place during use.
Burettes are glass tubes with a tap and valve at the outlet. They are used to precisely dispense small drops of liquid sample in titrations and measure the volume of liquid dispensed.
“Auto Zero” burettes are modified burettes attached to a bottle cap and immersed in the bottle’s liquid. In doing so, when liquid is filled into the burette, the excess liquid is automatically unloaded, and automatically, the volume is set to zero.
Pipettes are long and narrow glass tubes with a tapered tip. The liquid is drawn into the pipette from the tip with the help of a pipette bulb or pipette aid. Graduated pipettes are designed to precisely and accurately measure liquid samples. They are calibrated as “To Contain (TC)” or “To Deliver (TD)” liquid samples.
- Volumetric pipettes are graduated pipettes designed to measure and transfer a specific amount of liquid. They are characterized by a bulgy middle, a graduation line, and numbers specifying the volume they can accommodate.
- Serological or blow-out pipettes are graduated pipettes used to measure and transfer liquids. They accommodate a specific range of volume, ranging from 0.2-30mL. Serological pipettes are calibrated as TC. Thus, the liquid remaining in the pipette tips must be blown out to acquire the intended volume.
- Mohr pipettes or measuring pipettes are graduate pipettes similar to serological pipettes. Unlike serological pipettes, Mohr pipettes are calibrated as TD. For this reason, the remaining liquid in the tip of Mohr pipettes should not be blown out.
- Pasteur pipettes or droppers are ungraduated pipettes used to transfer and dispense a small amount of liquid by drops.
Laboratory Glassware Selection Guide
When choosing and purchasing glassware for your laboratory, it is essential to understand the intended activities and applications.
Here are a few points that you should deliberate on:
- Type of works and experiments dictate the necessary and appropriate type of glass and the lab glassware you should have. For example, borosilicate glassware is generally sufficient for most biochemical laboratories due to its durability and resistance to thermal and pressure stress. On the contrary, distillation and crystallization laboratories may also need a few quartz glassware because of its purity and superior compression strength.
- Laboratory size and budget can play a major role in the quality and quantity of the glassware available in the laboratory. Depending on the type of work performed in the laboratory, some of the glassware can be replaced with plasticware, saving a substantial amount of money.
- Work and storage areas should also be factored into deciding the quantity and type of glass to purchase. In general, different types of glassware should be stored in separate and designated cabinets and shelves. Borosilicate glassware is heavier than quartz and soda-lime glassware. Thus, borosilicate glassware requires a strong and sturdy cabinet and shelf for storage.
How to Clean Lab Glassware
Lab glassware is frequently exposed to chemical and biological samples, which can be toxic or even infectious. Therefore, contaminated glassware must be decontaminated by rinsing several times with warm tap water, soaking it in decontaminating solution, chemically sterilized, or autoclaved.
After decontamination, the waste should be discarded as per regulations. The decontaminated glassware should be further cleaned using commercial detergent.
If the decontaminated glassware is cleaned by hand, it should be soaked in warm, sudsy water before the glassware is washed with brushes and scrubs. Finally, the glassware can be thoroughly washed with water and rinsed with deionized water. Cleaned glassware can be air-dried or baked in a hot-air oven.
Dos and Don’ts of Handling and Maintaing Lab Glassware
Lab glassware is designed for a specific purpose. It must be used for only its designated purpose, handled, and cleaned according to the standards.
Nonetheless, extra precautions should be given when using glassware in the following circumstances:
- Heating glassware
- Before heating the glassware to an extra high temperature (above 100°C), always consult with manufacturers.
- Each piece of the glassware should be carefully inspected for chips and cracks before heating. If present, the glassware should not be heated regardless of the temperature used to prevent breakage and chemical spills.
- Do not leave glassware heating for a long period, especially when the chemical is present when heating.
- To avoid explosion, glassware rinsed with organic solvent must not be heated until the solvent is completely removed.
- Cooling glassware
- Like heating glassware, each piece of glassware must be inspected for chips and cracks before cooling or freezing it.
- Change the temperature slowly to prevent glass shattering – this includes cooling to ultra-low temperature and thawing.
- Glassware in a vacuum system
- Avoid putting glassware in a vacuum or high-pressure condition because it could explode. Always consult with the manufacturer if and to what extent the specific piece of glassware can withstand high pressure and vacuum.
- Diligently inspect glassware in a vacuum system for chips and cracks.
- Obtain appropriate personal protective equipment when using glassware in a vacuum and pressure system.
Lab glassware is essential to every laboratory. Borosilicate glassware is the go-to glassware in most laboratories due to its durability and high temperature and pressure resistance. Each type of glassware is designed for a specific function and should be handled with care and precautions.
Searching for quality and durable pipettes? Then check out our durable serological measuring pipette.
- Schott. Technical Glasses: Physical and Technical Properties, Schott AG.
- Thompson R.B. Illustrated Guide to Home Chemistry Experiments, 1st edition, Maker Media, Inc., 2008.
- National Research Council of the National Academies. Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards, National Academy of Sciences, 2011.