guide
Questions before a glassware enquiry
Which glass type, class, volume, joint size, cap thread and autoclave requirement to write down before a laboratory glassware enquiry.
- Author
- EVRINTH Editorial Team
- Published
- 8 October 2026
- Updated
- 8 October 2026
- Reading time
- 7 min
A glassware request that says only "flasks, assorted" cannot be compared with a method. The method already knows the missing words: glass type, class, volume, joint, thread, whether steam is involved, and how many pieces. This guide turns those words into an enquiry. The reasoning behind the words is choosing laboratory glassware.
The questions, in the order they prevent waste
What volume claim do you need? If the answer is a concentration other people will calculate from, the piece is a volumetric flask or another volumetric tool, with class and to-contain or to-deliver written down. If the answer is "about half full so I can swirl", the piece is a beaker or an Erlenmeyer flask and the graduation is a guide. Asking for a flask without this distinction buys a cone when you needed a neck mark, or a calibrated neck when you needed a mixing beaker.
What temperature will it see? Hot plate, drying oven, autoclave, or room temperature only. Heat and steam point to borosilicate 3.3 or another low-expansion type described for laboratory apparatus in ASTM E438. Room-temperature aqueous storage can be a broader choice, including some soda-lime or a charted plastic, and that choice should be explicit so it is not later autoclaved by mistake.
What does it connect to? A standard-taper joint has a size that must match the mate. A bottle has a thread, commonly GL45 for laboratory media bottles. A cryovial or a tube has a cap style that is not a glass joint. Write the number you measured on the existing piece. If you do not have the number, write that you will measure it, and do not let a quotation invent one.
What chemical touches it? Solvent, strong alkali, culture medium, or dilute aqueous buffer. Alkali stored for weeks does not belong in volumetric ware. Aggressive organics default to glass and a compatible liner. Culture medium that will be steamed needs borosilicate, headspace, and a cap policy. The chemical line protects the cap and the liner, which people forget because the glass is the larger object.
How many, of which specification? Quantity is a count of pieces of that specification. It is not a commercial adjective. Ten Class A flasks and two beakers are two lines.
What good answers look like
A volumetric line reads: borosilicate volumetric flask, stated capacity, Class A or Class B, to contain, reference temperature as printed or as required, with a certificate if your record needs one. NIST's Office of Weights and Measures is the background for why the certificate is a separate request from the glass itself. You do not need to type a tolerance you do not have in front of you. You need to say that the tolerance must be the class you named, documented.
A bottle line reads: borosilicate media bottle, capacity, GL45 or the thread you use, cap style, autoclave duty, liner compatible with the chemical. Say that ordinary caps will be loosened for steam unless you are specifically requesting a cap the manufacturer rates for closed venting. Say that you will not fill to the brim.
A jointed line reads: flask form, capacity, joint size, and whether a PTFE sleeve or a particular stopper is required. Add a second line for the condenser or adapter that must mate, with its joint size. One line without the mate is how mismatched cones arrive.
A plastic line, if any, reads: resin, format, autoclave mark if needed, and the solvent or buffer. Piston pipettes and tips are not glassware. If they ride along in the same enquiry, ISO 8655-1 is the vocabulary for the pipette, and the tip fit is a pipette-model sentence. Keep it off the flask line.
| Line | Include | Omit |
|---|---|---|
| Volumetric flask | Capacity, class, In or Ex, glass type, certificate if needed | A beaker described as accurate enough |
| Media bottle | Thread, cap, autoclave duty, headspace habit, liner chemistry | An unmarked jar called a bottle |
| Beaker or Erlenmeyer | Capacity, borosilicate if heated, baffles if culture | A volumetric class the beaker does not have |
| Jointed ware | Joint size of both mates | A photograph in place of the number |
| Plastic alternative | Resin and chart duty, separate from glass | A silent substitution |
Branch when you do not know
If the class is unknown, write the decision the volume supports. A primary standard that other laboratories must repeat is a Class A conversation. A teaching solution with a wide acceptance is a Class B conversation. Saying nothing invites a random substitution. If the joint size is unknown, measure the mate or send a careful description and mark the number as unconfirmed. Do not write 24/40 because it is a size you have heard.
If the chemical is a mixture, name the aggressive component. Charts and liners fail on the worst constituent, not on the average. If autoclave duty is "maybe later", specify for steam now or label the piece as not for autoclave. Maybe later is how soda-lime enters the basket.
If a previous piece cracked, say so. The replacement for starred, chipped or etched glass should name the same duty and the glass type, and it should not quietly downgrade to unmarked ware because that ware is easier to find.
Safety and research limits
An enquiry is not a biosafety approval and not a chemical-hygiene plan. If the glass will hold a culture or a hazardous solvent, your institution's rules still decide the room, the cabinet and the waste. The WHO laboratory biosafety manual is background for the biological side. Do not write a containment level into a glass order as if the bottle created it. Do not ask a supplier to tell you that a vessel is fit for diagnosis. This is research apparatus.
Specification writing where the room is hot and the paperwork is shared
Write the reference temperature you can really use. Ware marked 20 °C and ware marked 27 °C are different reading conditions, and a warm laboratory should say which one the method will follow. Write autoclave duty in a way the next shift cannot miss, because a shared facility will steam anything that looks like a media bottle. Write the thread. A GL45 cap cannot be assumed on every imported bottle. If a power cut or a queue changes when glass is washed, the specification still keeps volumetric pieces out of a harsh default cycle you did not intend. The document is the memory. A catalogue family name is not.
Where the sentence goes
Use the laboratory glassware catalogue to see forms, the volumetric glassware catalogue for marked volumes, and the laboratory plasticware catalogue only for lines that are honestly plastic. Send the specification through the quote request. Ask whether a quotation against that specification is possible. A family title on a page is not a measured tolerance and not a statement about any particular lot.
Write a glassware specification another person can quote against
- 01Name the measurement or the dutyState whether the piece must declare a volume, survive steam, mate with a joint, or only mix and hold. The duty chooses volumetric glass, a bottle, a beaker or a plastic alternative.
- 02Add the marks that prevent substitutionAdd glass type, capacity, Class A or Class B if volumetric, to contain or to deliver, joint size or cap thread, and whether an autoclave cycle is required.
- 03State the chemical and the countName the chemical family the glass and any cap or liner must meet. State how many pieces of that exact specification you need. Leave commercial terms out of the scientific line.
- 04Separate anything you do not knowIf the joint size or the class is unknown, say unknown and describe the mating piece or the accuracy the method needs. Do not guess a number that will be purchased as if it were measured.
Questions from the bench
What is the minimum a useful glassware enquiry contains?
Glass type, vessel form, capacity, and the duty: volumetric, heating, autoclave, storage, or jointed apparatus. Add class and reference temperature for volumetric pieces, joint size or thread where a mate exists, and the quantity as a count of pieces. A line that says only flasks, assorted, cannot be compared with a method. Two honest replies to that line can be completely different glass.
Why specify borosilicate 3.3 instead of a trade name?
A trade name identifies a manufacturer line. Borosilicate 3.3, or another type named in a glass specification, identifies the expansion behaviour you need for heat and steam. Some consumer products sold under familiar names in some markets are tempered soda-lime. If the enquiry says only the trade name, a correct quotation can still be the wrong composition. Put the glass type in the sentence and treat the trade name as optional extra detail.
How should autoclave duty be written?
Write that the vessel and its closure must be suitable for steam sterilisation under your laboratory's autoclave practice, that ordinary caps will be loosened unless a vented cap is requested, and that headspace will be left. Do not invent a cycle time in the enquiry if your institution already has one. Do name the thread, commonly GL45 for media bottles, so the cap and the bottle are one specification rather than two surprises.
Where do plastic items belong in a glassware enquiry?
On a separate line, with the resin and the chart duty. A polypropylene tube is not a substitute sentence under a borosilicate flask. If you are unsure whether the solvent allows plastic, say the solvent and ask for glass unless a named resin is documented. Mixing the two in one line is how a plastic cylinder arrives for a volumetric-flask job.
References
Manufacturer names identify published method classes. Trademarks remain with their owners. Catalogue records on this site are independent references for enquiry. They are not a statement of inventory, distribution rights or a supply commitment. This page is educational. It is not medical advice, a diagnostic protocol or a biosafety approval.
Catalogue
Related products and categories
These links follow the subject of the article into published manufacturer references. A listing is a reference for an enquiry, not a statement of stock or distribution rights.
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Related reading
Choosing laboratory glasswareHow to match borosilicate beakers, flasks and volumetric glass to the measurement you need, and when a printed line is only a guide.A glossary of labware termsDefinitions of the labware words that change a result: class marks, to contain and to deliver, joint size, resin, sterile and clean.Beakers are for handling not for accuracyWhy a beaker graduation is only a handling guide, and when a concentration other people will reuse belongs in a volumetric flask.