Frequently Asked Questions

How often should I examine my glassware for faults?

Before using any piece of glassware, take time to examine it carefully and ensure that it is in good condition. Do not use any glassware which is scratched, chipped or cracked. Defects like these can seriously weaken the glass and make it prone to breakage in use.

Try to always ensure that all volumetric glassware is kept meticulously clean and grease free. As dirt and especially grease, can affect the shape of the meniscus and so impair accuracy. Liquids cling to grease which impairs accuracy and affects the run out time.

Check jets for chips and cracks as they pose a safety hazard but also affect delivery times which may impede accuracy.

How do I get the maximum life and performance from my Glassware?

To obtain the maximum life and performance from glassware, the correct handling is essential. Take time to examine glassware carefully and ensure that it is in good condition.
Do not use any glassware which is scratched, chipped or cracked. Defects like these can seriously weaken the glass and make it prone to breakage in use.

Always provide adequate support to glassware at the base.

Do not lift, carry or suspend glassware by the neck, rim or side arms.

The use of hydrofluoric acid, hot concentrated phosphoric acid and very strong alkalis is to be avoided in borosilicate glassware as these chemicals attack and weaken the glassware.

What is the maximum temperature that I can heat my glassware?

The maximum recommended working temperature for Pyrex® and Quickfit® glassware is 500°C (for short periods only). However, once the temperature exceeds 150°C extra special care should be taken to ensure that heating and cooling is achieved in a slow and uniform manner.

Do heat vessels gently and gradually to avoid breakage by thermal shock. Similarly, allow hot glassware to cool gradually and in a location away from cold draughts.

If using a hotplate, ensure that the top plate is larger than the base of the vessel to be heated. Also, never put cold glassware onto a hotplate which is already well heated.

Warm up gradually from ambient temperature.
If using a Bunsen burner, employ a soft flame and use wire gauze with ceramic centre to diffuse the flame.
Never apply high temperature heat sources directly to any item of volumetric glassware.

How do I prevent Quickfit joints from seizing?

Lubricate joints with good quality laboratory grease or alternatively use PTFE tape or PTFE joint sleeves to avoid any contamination to sensitive reactions.

What do I do if a PTFE component seizes within glass, such as a stopcock or stopper?

Place the piece of glassware containing the PTFE component (stopcock, stopper, etc.) into an ice bath for approximately 15-20 minutes. Remove the glassware from the ice bath. The ice bath should contract the PTFE component enough to allow the pieces to be separated.

Is Pyrex suitable to use on hotplates?

Pyrex glassware is made from Borosilicate glass which has a maximum working temperature of 500oC (for short periods of time only).
Special care should be taken at temperatures above 150oC. Ensure that that both heating and cooling are achieved in a slow and uniform manner in order to avoid thermal shock. Do not directly heat glassware on a hotplate as this can create ‘hot spots’ on the glassware which may cause the glassware to shatter.

A heating mantle is the best option for heat a round bottomed flask. Another option would be to use sand, oil or water bath is one method of offering a slow and uniform heat to other glassware such as beakers.

When using water or oil, buoyancy can be a problem is there is not enough weight or support to keep the glassware in position. A sand bath can get around the buoyancy problem and provide a greater surface area.

Does Sintered glassware have the same properties as Pyrex?

Yes. Sintered glassware is made from same borosilicate glass as Pyrex therefore giving the sinters the same chemical and heat resistance to temperatures as Pyrex.

New apparatus with sintered glass discs should be washed before use to remove loose particles of dust etc. Wash through with hot dilute hydrochloric acid followed by a thorough rinse with water.

> Never subject sintered glassware to differential pressures exceeding 100kN/m2 (15psi).

Avoid subjecting sintered glassware to sudden temperature changes or to direct flames.

Always heat very gradually. Similarly, cooling should be achieved in a uniform and gentle manner.

How do I decide on the size of glassware to purchase?

Before proceeding with an experiment, it is best to plan which glassware you will need before hand, do not compromise when selecting glassware whilst setting up equipment. Be pragmatic. Use the most appropriately sized glassware for the volumes you wish to use.

Never overfill glassware when heating or boiling reagents. Similarly do not use glassware that is too large in volume when using small amounts of reagents.

The glassware I want is not listed. What can I do?

At SciLabware we can help design and manufacture customised and bespoke glassware to suite your precise needs.

Please email with details of your custom design.

Can I order directly from SciLabware?

All items listed in the SciLabware catalogue are only sold through authorized distributors.

However we can directly supply custom designed glassware and we welcome all enquires.

For Custom Glassware email

How can I extend the lifetime of my glassware?

By trying to minimise drops, knocks and bumps you can extend the lifetime of your glassware.

Also, avoid being heavy handed, over filling, over heating, and using the incorrect glassware for a specific experiment.

Clean your glassware immediately after use.

What are the differences between Class AS and Class A?

SciLabware recently replaced Class A pipettes and burettes with Class AS products. Class AS is the European standard and the UK in now adopting this standard.

Class AS and Class A share the same high accuracies and tolerances to the relevant ISO and DIN standards.

Class AS has faster delivery from a re-engineered jet (the time taken to dispense the total volume), with the addition of a waiting time before reading is taken or vessel is emptied (the time taken for the meniscus to settle).

How can I locate my nearest distributor?

Please refer to the ‘Where to buy’ tab located at the top of the SciLabware website next to ‘FAQ’s’ or follow this link.
Select a continent by clicking on the map and then selecting the country of interest, or simply scroll down the page to select your country.

What are the differences between items that are calibrated ‘To Contain’ and ‘To Deliver’?

All calibrated volumetric glassware requires that the user be informed whether the glassware is calibrated ‘To Contain’ or ‘To Deliver’.

Glassware that is designed ‘To Contain’ holds set volume. Glassware that has been calibrated ‘To Deliver’ delivers a set volume of liquid to another vessel regardless of any drips or liquid that remains in the glassware after the run out.

Displayed on the glassware the calibration information is displayed as ‘EX’ to deliver and ‘IN’ to contain.

What is the difference between soda lime glass and borosilicate glass?

Soda lime glass is the most common commercial glass, and also the least expensive. Soda-lime glass is not very resistant to high temperatures, sudden thermal changes or corrosive chemicals.

Borosilicate glass has a low thermal expansion coefficient and high chemical resistance, making it ideal for use in laboratories and the medical and pharmaceutical industries.

What is amber coated glassware used for?

Amber glass is used in laboratories for the protection of UV sensitive chemicals and materials such as chlorinated chemicals or bio-cultures.

Amber glass blocks all UV radiation from 350 to 200nm. The UVC range used for germ killing purposes, between 200 to 280nm is also blocked. But not all UV radiation is blocked by the amber glass.

What do Class A, Type 1, and Type 3.3 borosilicate glass refer to?

Type 1, Class A and Type 3.3 are the specifications from different standards that refer to borosilicate glass. Type 3.3 is so named because of the coefficient of expansion for borosilicate glass is 3.3x10-6K-1 (20 - 300°C).

The following standards use the associated specifications of borosilicate glass. Pyrex borosilicate glass meets the specifications of all the following standards.

ISO 3585, DIN 12217 - Type 3.3 borosilicate glass
ASTM E-438 - Type 1 Class A borosilicate glass
US Pharmacopeia (USP) - Type 1 borosilicate glass
European Pharmacopeia (EP) - Type 1 glass

What does fire-polish mean?

Fire polishing is a technique employed in glass fabricating. When a glass rod or tube is cut, it leaves a rough, sharp finish. When a flame is applied to reach the softening point, it seals or “polishes” the end to a smooth, glassy finish or “polish,” thus the term "fire polish". The end of a piece of glass can be ground to a finish or “flame” or “fire-polished”, reducing any potential injuries.

All SciLabware products are finished to same high standards with our customer’s safety in mind.

What are good cleaning techniques for laboratory glassware?

Laboratory procedures require exact methods and should include good glassware cleaning to insure excellent experiment results. In all instances labware should be physically clean, including both chemical residue free and grease free, and in many cases even be sterile.

All volumetric glassware that is used in precise measuring of liquids should have surfaces that can be fully wetted. A good test is to use distilled water and see if the water wets all the inner surfaces equally. Grease or residues will not only contaminate the reaction and test results but will also alter the measurement of the liquids.

Good cleaning practices should also be accompanied by a thorough inspection. Check the glass surfaces for chips, cracks or abrasions which will cause mechanical failure.

Always wash glass labware immediately after use. If a thorough cleaning is not immediately possible, always allow the glassware to soak. If not cleaned immediately some residues may be impossible to remove.

Never soak glassware for long periods in very strong alkaline solutions as it will damage the glass.

Always follow up with a detergent or acid wash with a good rinse with de-ionised water. SciLabware recommends using Lipsol detergent with glassware. Always use soft brushes with a wooden or soft plastic handle to avoid abrasion. Do not use wire brushes or brushes with a wire core as it can abrade the glass.

What glassware cleansers are recommended by SciLabware?

SciLabware only recommends using Lipsol detergent with our glassware.

Occasionally, stronger acid washes are necessary for certain types of precipitates or residues. It is best to keep these very dilute and be used in an area where there is good ventilation.
Make sure you contain the residual acid and dissolved material for proper disposal. This method should only be used when absolutely necessary.

The disposal of seriously stained glass maybe a less troublesome and less expensive course of action than using strong acid washes.

How do I remove grease from my glassware?

Grease is best removed by boiling the glass in a weak solution of sodium carbonate. Acetone or any other organic solvent can be used also, followed by several water and de-ionised water rinses.

How do I remove stains from my glassware?
To remove stubborn stains soak in a solution of 3% sulphuric acid and 3% hydrogen peroxide.
To remove iron stains use a solution containing one part hydrochloric acid and one part water.
Caution: Make sure you refer to MSDS sheets for the cleaning solutions and the materials that were in the glassware. Ensure that there will not be any adverse reactions from the combination of the materials.
How do I clean glassware that has been used in cell and microbiology?

Bacterial contaminated glassware used in cell and microbiology should be soaked in a disinfectant solution and then steam autoclaved followed by a suitable washing and rinsing.

Caution: Make sure you refer to MSDS sheets for the cleaning solutions and the materials that were in the glassware. Insure that there will not be any adverse reactions from the combination of the materials.

Can I use Ultrasonic Cleaners to clean my glassware?

Ultrasonic cleaning is a good method of cleaning glassware thoroughly.

Ultrasonic cleaners that use heaters are the best. Generally, using an ultrasonic cleaner with a mild detergent will clean most residues from the glassware.

Why do I need to rinse my glassware after a cleaning procedure?

Rinsing glassware is important after any cleaning procedure to remove any left over residue from improper draining, and to remove water marks.

Glassware should always have a water rinse after any cleaning procedure followed by a thorough rinse with de-ionised water.
Glass pipettes are best soaked in a suitable pipette washer.

How should I dry my glassware?

Using a drying oven at 100°C is the most efficient way to remove all moisture from your glassware. If a drying oven is not convenient, use a rack to dry your glassware. Ensure good air circulation by not over filling the drying rack and that water run off is easily drained away.

What porosities are found in sintered glassware?

Sintered glass discs are graded from 0 – 4 depending on their respective porosity.

• Grade 4: with pore sizes from 10 µm - 16 µm (microns)
• Grade 3: with pore sizes from 16 µm - 40 µm (microns)
• Grade 2: with pore sizes from 40 µm - 100 µm (microns)
• Grade 1: with pore sizes from 100 µm - 160 µm (microns)
• Grade 0: with pore sizes from 160 µm - 250 µm (microns)

What bore size tubing is needed to connect to screwthread connectors?

All screwthread connectors fit 13mm screwthreads, and allow 9mm bore rubber hose and flexible tubing to be attached.

What is a ‘hot spot’?

When heating or cooling glassware always ensure that this is done in a uniform manner, preferably using a heating mantle.

Temperature variances over 100°C across the vessel can cause a 'hot spot', where one area of the glassware item is hotter than the rest of the item. Hot spots can lead to breakages therefore it is import to heat in a slow and uniform manner.

The maximum recommended working temperature is 500°C for short periods of time only, we recommend no higher than 400°C. <

Extra care should be taken at temperatures above 150°C.

Care should always be taken when heating any concentrated acids, wear personal protection and setup protective screens.

What is an autoclave used for?

An autoclave is a device used to sterilise equipment by subjecting them to high pressure steam.
A typical autoclave cycle is dependant on the temperature and time for the appropriate sterilisation. Cycles can lasts 30 minutes at 115oC, 15 minutes at 121oC or for 3 minutes at 134oC.

Cycle times also vary according to the load. Autoclaves can also have either water cooling or fan assisted air cooling to provide a uniform and a gradual temperature decrease.
SciLabware recommends autoclaving at 121oC for 30 minutes.

Are the keys of Springham stopcocks 'interchangeable'?

Yes, all Springham brand general purpose stopcocks have fully interchangeable keys. However, please note that a glass key will not fit a barrel designed to take a PTFE key nor vice versa. Springham¨ high vacuum stopcocks are not interchangeable and are individually numbered to ensure that the key can always be matched with the correct barre.

Can Erlenmeyer flasks be used under vacuum?

No, flat bottomed vessels should never be used under vacuum. The only exceptions are those products designed specifically for that purpose, e.g.Buchner filter flasks and Quickfit¨ "heavy wall" Erlenmeyer flasks (code FEH:).

N.B. Pyrex "Heavy Duty" Erlenmeyer flasks are not designed to be used under vacuum.

Can I autoclave Pyrex media bottles?

Yes, the bottle, polypropylene pouring ring and cap are safe up to 135°C. For higher temperatures (up to 200°C) a melamine cap and ETFE pouring ring should be used (codes 4526: and 4536: respectively).

In all cases ensure that the cap is not fully tightened as pressure differences could build up and cause failure of the bottle.

Can I use Pyrex vessels in a microwave oven?
Yes, Pyrex borosilicate glass is completely microwave safe. However, as with any microwave vessel, be sure it contains a microwave absorbing material such as water before placing in the oven.

Note also that fittings such as plastic caps may not necessarily be microwave proof.