Flask, Conical (Erlenmeyer)

Quick Answer: An Erlenmeyer flask is a conical laboratory flask with a flat base, straight sloping sides and a narrow cylindrical neck. Named after the German chemist Emil Erlenmeyer, it is used for mixing by swirling, heating and holding solutions, recrystallisation and growing liquid cultures.

Why the Erlenmeyer Shape Has Lasted

Emil Erlenmeyer introduced the conical flask in the 1860s, and its geometry has changed little since. The wide base gives a large heating surface and a low centre of gravity, the sloping walls redirect a swirled liquid inwards, and the narrow neck limits evaporation and can be closed with a bung, a cotton-wool plug or foil. Together these make it the default container in chemistry and microbiology laboratories for tasks that combine mixing with a moderate amount of heat.

In recrystallisation, for example, a hot saturated solution cools more slowly and loses less solvent from this conical shape than from a beaker, and the crystals that form can then be collected by suction filtration. In microbiology the same shape carries broth cultures on a shaker platform, where the sloping walls keep the medium moving without spilling.

The listing does not state capacity, glass type or whether the neck is plain, beaded or fitted with a ground joint. If a set of several sizes is wanted in one order, see the assorted conical flask set.

Specifications

Design	Erlenmeyer pattern: flat base, conical body, narrow cylindrical neck
Closure options	Rubber bung, cotton-wool plug, foil or screw cap, depending on neck finish
Typical use	Swirl mixing, heating solutions, recrystallisation, liquid cultures
Graduations	Approximate filling guide only, where present
Capacity, glass type and neck finish	Confirm at enquiry

Applications

Recrystallising crude organic solids such as benzoic acid or acetanilide from hot water or ethanol
Preparing and sterilising culture media, with the neck closed by a cotton-wool or foam plug
Growing bacterial or yeast cultures in liquid broth on a shaker
Collecting a filtrate or distillate where a narrow neck reduces evaporation
Titrations in college analytical chemistry practicals

Care & Handling

Heat the flask on a hot plate or over a gauze and swirl the liquid from time to time; never heat an empty flask.
When autoclaving, cover the neck with a loose plug or foil so steam can enter and pressure cannot build.
Clean the inside of the shoulder, where residues collect out of reach, with a curved flask brush.
Hold a hot flask by the neck with tongs or a heat-resistant glove, not bare fingers.

Why Choose LabEquip

College chemistry departments, microbiology labs and school preparation rooms get through conical flasks faster than most glassware because the flask serves so many tasks. They are stocked with LabEquip’s chemistry lab equipment; tell us the sizes, neck type and quantities on the contact page.

Frequently Asked Questions

Is an Erlenmeyer flask the same as a conical flask?

Yes. The two names describe the same flat-based, cone-shaped design. Some catalogues use conical flask for school listings and Erlenmeyer for college or microbiology listings, but the shape is identical.

Why is a conical flask better than a beaker for recrystallisation?

The narrow neck reduces solvent loss and cooling from the surface, so the hot solution stays saturated and cools slowly, which favours larger, purer crystals. The shape also makes it easy to swirl while adding hot solvent a little at a time.

Can this flask be used under vacuum?

No. Standard conical flasks have relatively thin walls and a flat base, which can fail under a pressure difference. Suction filtration needs a heavy-walled filtering flask with a side arm, which is built for that purpose.

How should the neck be closed for autoclaving media?

Use a cotton-wool or foam plug, or a loose foil cap, so steam can reach the medium and air can escape. Never autoclave a flask closed with a tight bung or screw cap, as pressure inside can crack the glass.

Is this flask suitable for liquid cultures?

Yes. The flat base sits steadily on a shaker platform, and the narrow neck takes a cotton-wool or foam plug that lets air in while keeping dust and airborne microbes out. Baffled versions, with indentations in the base, improve aeration further where needed.

Can the flask go directly on a hot plate?

Glass flasks can generally be heated on a hot plate if the glass type suits it and the plate is warmed gradually. Confirm the glass type, and keep the flask no more than about half full so boiling liquid cannot climb the neck.

Last Updated: September 2026

Flask, Conical (Clear Glass)

Quick Answer: A clear glass conical flask is a flat-based, cone-shaped glass flask with a narrow cylindrical neck, used for titrations, mixing and holding solutions. The transparent wall lets students watch colour changes and dissolving solids, while the sloping sides keep the liquid in when it is swirled.

Reading Colour Changes Through a Clear Glass Wall

The conical flask is the vessel in which most school titrations finish. Its flat base stands on a white tile beneath the burette, the sloping sides turn the liquid back on itself when the flask is swirled by hand, and the narrow neck catches splashes that an open beaker would lose. In a clear glass conical flask the end point colour, such as the first permanent pink of phenolphthalein or the orange of methyl orange, can be judged against the tile without any tint from the glass.

The title names clear glass but not the glass composition. In laboratory catalogues a clear glass listing is often the ordinary soda-lime alternative to borosilicate, and soda-lime glass expands roughly three times as much as borosilicate when heated, which makes it less tolerant of sudden temperature change. That matters little for titration, mixing and room-temperature reactions, but the glass type should be confirmed before the flask is used for boiling or placed on a hot plate.

Where heating is part of the practical, the separately listed Erlenmeyer conical flask is the listing to compare. Graduation marks on conical flasks, where present, are approximate filling guides rather than measuring marks; volumes that count should come from a pipette, burette or measuring cylinder.

Care & Handling

Swirl with the wrist while holding the neck, rather than shaking the flask up and down, so liquid is not thrown out.
Set a warm flask on a heat-resistant mat and let it cool before washing; cold water on hot glass is a common cause of cracks.
Remove titration residues promptly, especially permanganate stains, which clear far more easily while fresh.
Discard any flask with a chipped rim or a star crack in the base, where stress concentrates during handling.

Specifications

Item	Conical flask with flat base, sloping sides and narrow neck
Material	Clear glass, as named in the title; composition not stated
Main uses	Titration, mixing by swirling, dissolving, holding solutions
Heating	Gentle warming on a gauze only, until the glass type is confirmed
Capacity and neck finish	Confirm at enquiry

Applications

Titrating hydrochloric acid with sodium hydroxide solution, the flask standing on a white tile below the burette
Iodine-thiosulfate and permanganate titrations, where a clear wall helps students judge a faint end point
Rate of reaction practicals with sodium thiosulfate and acid, in which students watch a pencil cross beneath the flask disappear
Dissolving weighed solids and mixing solutions before they are transferred to a volumetric flask

Why Choose LabEquip

Schools running class titrations need many identical flasks, and a clear body makes the end point easier for beginners to see. LabEquip supplies conical flasks within its chemistry lab equipment range; send the capacities and quantities for your practical sets through the contact page.

Frequently Asked Questions

Why use a conical flask instead of a beaker for titration?

The sloping sides and narrow neck let you swirl the solution vigorously without losing any, and drops from the burette land in a small target area. A beaker’s straight sides and wide top make splashing and loss more likely when it is swirled.

Is a clear glass conical flask suitable for heating?

Gentle warming over a gauze is usually acceptable, but ordinary soda-lime glass is more likely to crack than borosilicate if it is heated quickly or cooled suddenly. Confirm the glass type before boiling liquids in it or using a hot plate.

Can I measure volumes with the marks on a conical flask?

Treat any marks as rough filling guides only. In a titration the volume that matters is read from the burette and the aliquot is delivered by pipette, so the flask itself does not need to be accurate.

Why do I need a white tile under the flask?

A white background makes the first faint, lasting colour change easier to see, particularly with phenolphthalein, where the end point is a very pale pink. A sheet of white paper does the same job.

How do I remove brown stains left by potassium permanganate?

The brown deposit is manganese dioxide. A little acidified hydrogen peroxide or a dilute oxalic acid solution dissolves it; rinse thoroughly with tap water and then distilled water, and wear gloves and eye protection while cleaning.

Should the flask be rinsed with the solution before a titration?

No. Rinse the conical flask with distilled water only. The amount of reactant is fixed by the pipette, and rinsing with the solution would leave extra reactant behind, whereas water left in the flask does not change the number of moles present.

Last Updated: September 2026

Flask, Boiling, Two/Three Neck (Round/Flat Bottom)

Quick Answer: A two neck or three neck flask is a boiling flask with extra side necks around its main neck, so several pieces of apparatus can be fitted at once, such as a condenser, a thermometer and a dropping funnel. This listing covers two-neck and three-neck versions with round or flat bottoms.

One Flask, Several Openings

A single-neck flask allows one fitting at a time: a condenser, a thermometer or an addition funnel. Many preparations need more. A reaction heated under reflux while a reagent is added dropwise and the temperature is watched needs three openings, and a three-neck flask provides them: a central neck, usually for the condenser or a stirrer, and two side necks for a dropping funnel, a thermometer or a gas inlet.

A two-neck flask is the simpler option when only two fittings are needed, such as a condenser plus a thermometer or a gas inlet. Side necks may be straight or angled away from the centre, and angled necks give more room between fittings. The listing does not state the neck arrangement, joint sizes, capacity or glass type, and it covers both round and flat bottomed forms, so specify all of these when ordering.

Round bottomed versions are the usual choice for heating in a mantle and for reduced-pressure work, while flat bottomed versions stand on a bench or hot plate and suit gentle warming with magnetic stirring. Either way, every fitting in a multi-neck set-up should be clamped or clipped, because the extra weight makes the assembly top-heavy.

Applications

Reactions heated under reflux while a reagent is added dropwise
Preparations that need the temperature of the reaction mixture monitored throughout
Reactions under an inert gas, with the gas inlet and outlet on separate necks
Mechanically stirred reactions with the stirrer passing through the central neck

Specifications

Item	Boiling flask with two or three necks
Bottom	Round or flat, as listed
Necks	Central neck plus one or two side necks
Typical fittings	Condenser, dropping funnel, thermometer, stirrer guide, gas inlet
Neck count, joints, capacity and base	Confirm at enquiry

Care & Handling

Close any unused neck with a matching stopper so vapour cannot escape and dirt cannot enter.
Clamp the flask at the central neck and support heavy side fittings separately.
Make sure the thermometer bulb dips into the liquid if the reaction temperature, rather than the vapour temperature, is to be measured.
Clean each neck and joint surface individually; residues trapped where the necks meet the body are easy to miss.

Why Choose LabEquip

Organic synthesis courses and research laboratories use multi-neck flasks when a preparation needs more than one fitting. LabEquip lists them in the chemistry lab equipment range next to the single-neck short neck boiling flask; send the neck count, joint sizes and base shape you need through the contact page.

Frequently Asked Questions

When do I need three necks instead of two?

Choose three necks when three fittings are needed at once, for example a condenser, a dropping funnel and a thermometer. A two-neck flask is enough for two fittings, such as a condenser and a gas inlet.

What goes in the central neck?

The central neck usually carries the reflux condenser or, in stirred reactions, the stirrer shaft and its guide, because it sits directly above the centre of the flask. Side necks take the addition funnel, thermometer or gas inlet.

Should I choose a round or flat bottom?

Round bottoms heat more evenly in a mantle and are suitable for reduced pressure. Flat bottoms stand on a bench and sit well on a hot plate with a magnetic stirrer, but should not be used under vacuum.

Are angled side necks better than straight ones?

Angled necks point fittings away from the centre, leaving more room between the condenser, funnel and thermometer. Straight necks keep the assembly narrower. Either works if the fittings can be clamped without strain.

How do I add a reagent dropwise to a multi-neck flask?

Fit a pressure-equalising dropping funnel to a side neck, fill it with the reagent and open the tap slowly while the mixture is stirred. Watch the temperature and slow the addition if the reaction becomes too vigorous.

What should be done with unused necks?

Close them with ground-glass or PTFE stoppers of the right size. An open neck lets solvent vapour escape and allows moisture or air into reactions that must be kept dry.

Last Updated: September 2026

Flask, Boiling, Short Neck with Interchangeable Joint

Quick Answer: A short neck boiling flask with interchangeable joint is a boiling flask whose short neck ends in a ground-glass standard taper socket. The joint lets condensers, still heads, adapters and stoppers with the matching cone fit directly, without rubber bungs.

What an Interchangeable Joint Changes

Older apparatus was joined with corks and rubber bungs, which scorch, swell in solvents and leak. Interchangeable ground joints replaced them: every socket and cone of a given size is ground to the same taper, so any flask can be connected to any condenser or adapter with the same joint size, making a close, solvent-resistant seal. A flask of this kind is the base of such an assembly.

The short neck keeps the assembly compact. It sits low in a heating mantle, brings the joint close to the flask body so vapour reaches the still head or condenser quickly, and reduces the height of a reflux or distillation stack on a retort stand. Long-neck flasks, by contrast, are chosen where the neck itself must stay cooler or keep a joint away from the heat.

Joint size is the specification that matters most, because a flask is of little use if its socket does not match the cones on the rest of the kit. The listing does not state the joint size, capacity or whether the base is round or flat, so these should be checked against the condensers and adapters already in use.

Care & Handling

Apply only a thin smear of joint grease to the upper part of the cone, or use a PTFE sleeve; grease inside the flask contaminates the product.
Secure each joint with a plastic joint clip so the flask cannot slide off the condenser.
Take joints apart soon after use; left assembled, especially with alkaline residues, they can seize.
Protect the ground surface from knocks and grit, which scratch it and cause leaks.

Specifications

Item	Boiling flask with a short neck and ground-glass socket
Joint	Interchangeable standard taper socket at the neck
Neck	Short, for compact assemblies and heating mantles
Connects to	Condensers, still heads, adapters and stoppers with matching cones
Joint size, capacity and base shape	Confirm at enquiry

Applications

Reflux set-ups with a condenser fitted directly into the neck
Simple distillation with a still head and condenser
Organic preparations where cork or rubber would be attacked by solvents
Teaching assemblies in which students build apparatus from standard jointed parts

Why Choose LabEquip

College and university organic laboratories standardise on jointed glassware so that flasks, condensers and adapters all fit together. LabEquip lists this flask in its chemistry lab equipment range with jointed condensers such as the Graham condenser; send your joint size and capacities via the contact page.

Frequently Asked Questions

What does interchangeable joint mean?

It means the ground-glass socket on the flask is made to a standard taper and size, so it fits any cone of the same size on condensers, adapters or stoppers. Parts from different sets can be combined as long as the joint sizes match.

How do I know which joint size I need?

Look at the markings on the cones of your existing condensers and adapters, which usually give two numbers for the diameter and length of the ground zone. Order the flask with the same joint size.

Should ground joints be greased?

For most reflux and distillation work at normal pressure, a very thin film on the upper part of the cone, or a PTFE sleeve, is enough. Heavier greasing is kept for vacuum work, and grease should never reach the inside of the apparatus.

Why choose a short neck rather than a long neck?

A short neck keeps the apparatus compact and fits a heating mantle well, and vapour reaches the condenser quickly. A long neck is chosen when the neck needs to stay cool or keep the joint away from the heat source.

What should I do if a joint is stuck?

Do not force it. Gently warm the outer socket with warm water so it expands slightly, then twist the parts apart while wearing thick gloves. A light tap on the socket with a wooden handle can also help.

Can the flask be heated in a heating mantle?

Yes, provided the mantle is sized for the capacity and shape of the flask. Mantles heat evenly and have no open flame, which is safer with flammable solvents.

Last Updated: September 2026

Flask, Boiling, Round Bottom

Quick Answer: A round bottom flask is a spherical glass boiling flask with a neck, used for heating, boiling, distilling and refluxing liquids. The spherical body spreads heat and stress evenly, so it generally copes with strong heating and vacuum better than a flat-based vessel.

Why the Sphere Is the Shape for Heating

A sphere has no corners and no flat panels, so heat applied from below spreads evenly through the glass, and a pressure difference, as in vacuum distillation, is carried evenly by the whole wall. That is why the round bottom flask is the standard reaction and boiling vessel of organic chemistry and the default flask in distillation and reflux set-ups.

Because it cannot stand by itself, it is always supported: clamped at the neck to a retort stand, rested in a cork ring on the bench, or seated in a heating mantle shaped to its curve. Mantles, oil baths and water baths suit it better than a direct flame, which can create a hot spot on the glass. The listing does not give capacity, neck form or glass type.

In a typical distillation the flask carries a still head and thermometer and leads to a Liebig condenser; for reflux it carries a vertical condenser such as the Allihn condenser. Its size is normally chosen so that the liquid fills between a third and a half of the bulb.

Specifications

Item	Boiling flask with a spherical body
Body	Spherical, for even heating and resistance to pressure difference
Support	Clamp at the neck, cork ring or heating mantle
Heating methods	Heating mantle, oil or water bath, or gauze and burner
Capacity, neck and glass type	Confirm at enquiry

Applications

Simple and fractional distillation
Heating under reflux in organic preparations
Vacuum or reduced-pressure distillation, where a flat-based vessel would be unsafe
Removing solvent from a solution under reduced pressure

Care & Handling

Fill no more than about half full for distillation, so boiling liquid cannot splash into the still head.
Add anti-bumping granules to the cold liquid, never to a hot one, which could boil over suddenly.
Inspect for star cracks and scratches before vacuum use, as a flawed flask can implode.
Rest the flask in a cork ring whenever it is put down, never directly on a flat bench.

Why Choose LabEquip

College laboratories and research groups use more of these flasks than almost any other vessel, in sizes matched to their condensers and mantles. LabEquip supplies them in its chemistry lab equipment range; send sizes and neck requirements through the LabEquip contact page.

Frequently Asked Questions

Why does the flask need a cork ring?

Its curved base cannot stand on a flat surface and would roll over. A cork ring or flask stand holds it upright on the bench, and a clamp at the neck holds it steady during heating.

Is a round bottom flask safe for vacuum distillation?

Its spherical shape suits work under reduced pressure, provided the glass is free of cracks and scratches. Inspect it before each use and work behind a safety screen during vacuum distillation.

When should I choose it over a flat-based flask?

Choose it for distillation, reflux, vacuum work and long periods of heating. A flat-based flask is more convenient only when the vessel must stand on its own for simple heating or gas preparation.

How is the flask heated evenly?

A heating mantle that fits the curve of the flask, or an oil or water bath, gives even heating without hot spots. If a burner is used, heat through a gauze and keep the flame moving at first.

Why do liquids bump when boiled in it?

Smooth glass has few points where bubbles can form, so a liquid can overheat and then boil suddenly. Anti-bumping granules or a magnetic stirrer provide sites for steady bubbling.

How should it be cleaned?

Rinse out residues with a suitable solvent, then fill with warm detergent solution and scrub with a curved flask brush that reaches the walls. Rinse with distilled water and dry upside down on a peg rack.

Last Updated: September 2026

Flask, Boiling, Flat Bottom

Quick Answer: A flat bottom flask is a round-bodied glass boiling flask with a flattened base, so it stands upright on a bench, gauze or hot plate without a support ring. It is used for heating liquids, preparing solutions and generating gases in simple set-ups.

A Boiling Flask That Stands on Its Own

This flask combines the round body of a boiling flask with a base flattened enough to stand on. That makes it convenient in school laboratories: it can sit on a gauze over a tripod, on a bench mat while a bung is fitted, or on a hot plate, without the clamps and cork rings a round-based flask needs.

It is the generating flask in many classic gas preparations. Fitted with a two-hole bung carrying a thistle funnel and a delivery tube, it produces hydrogen from zinc and dilute sulfuric acid, or carbon dioxide from marble chips and dilute hydrochloric acid, with acid added through the funnel as needed. It is equally at home boiling water in heat experiments or dissolving solids with warming.

The flattened base is also its limitation. A flat glass surface is weaker under a pressure difference than a sphere and heats less evenly, so the flask should not be used under vacuum or for heating to dryness. For reduced-pressure distillation or long, strong heating, a round bottom flask is the right choice. Capacity and glass type are not given in the listing.

Applications

Gas generation with a thistle funnel and delivery tube for hydrogen or carbon dioxide
Heating water or solutions over a tripod and gauze
Dissolving solids with gentle warming when preparing solutions
Simple distillation demonstrations at atmospheric pressure, with the flask clamped at the neck

Specifications

Item	Boiling flask with a flat base
Standing	Stands unsupported on a bench, gauze or hot plate
Heating	Over gauze or on a hot plate; avoid heating to dryness
Not suited to	Vacuum work or reduced-pressure distillation
Capacity and glass type	Confirm at enquiry

Care & Handling

Always put the flask on a wire gauze when using a burner; a direct flame on the flat base causes hot spots and cracks.
Clamp the neck as well when a bung, funnel and tubing are fitted, as the loaded flask can topple.
Never connect this flask to a vacuum pump.
Cool the flask gradually on a heat-resistant mat, not on a cold, wet bench.

Why Choose LabEquip

Schools set up flat-based flasks for gas preparations and heating practicals where a self-standing vessel keeps the apparatus simple. LabEquip lists it in the chemistry lab equipment range; send the capacities you need through the contact page.

Frequently Asked Questions

What is the difference between a flat bottom and a round bottom flask?

A flat bottom flask stands on its own and suits simple heating and gas preparation. A round bottom flask needs a clamp or cork ring but heats more evenly and withstands vacuum and prolonged strong heating better.

Can a flat-based flask be used for vacuum distillation?

No. The flat base is weaker than a curved surface under a pressure difference and could implode. Use a round-based flask for any work under reduced pressure.

Why does a thistle funnel have to dip below the liquid?

If the lower end of the funnel is above the liquid, the gas produced escapes up through the funnel instead of the delivery tube. Keeping it below the surface forms a seal while still letting acid be added.

Can the flask be heated on a hot plate?

Yes, the flat base sits well on a hot plate. Heat gradually and do not let the flask boil dry, since the base can crack when it overheats without liquid in it.

How much liquid should be put in for boiling?

Fill it no more than about half full and add a few anti-bumping granules before heating. This leaves room for boiling and reduces the chance of sudden, violent boiling.

Can it be used instead of a conical flask in titrations?

It can hold the solution, but a conical flask is preferred because its sloping sides let the liquid be swirled vigorously without splashing out. The rounded shoulder of a boiling flask spills more easily when swirled.

Last Updated: September 2026

Test Tube with Stopper

Quick Answer: A test tube with stopper is a test tube supplied with a closure that seals its mouth, so the contents can be shaken, kept or carried without spilling or evaporating. It is used for shaking tests, sample storage and reactions that must be kept away from air.

Why a Test Tube Needs a Stopper

Many classroom tests are shaking tests. Hard water is compared with soft water by shaking each with soap solution and measuring the lather; an alkene decolourises bromine water when the two are shaken together; and one liquid is extracted into another by shaking and letting the layers settle. An open tube cannot safely be shaken with a thumb over its mouth when the contents are corrosive, so a stoppered tube is the proper way to do it.

A stopper also turns a test tube into a small sample container for a water sample taken on a field trip, a portion of a prepared reagent, or a precipitate kept until the next lesson. Sealed, the contents lose less to evaporation and pick up less dust or carbon dioxide from air. The stopper material, whether rubber, cork, plastic or ground glass, and the tube size and glass are not stated in the listing.

A stoppered tube must never be heated. Warming the closed tube raises the pressure inside until the stopper blows out or the glass bursts, so remove the stopper before any heating and replace it only after the tube has cooled.

Specifications

Item	Test tube with a sealing stopper
Purpose	Shaking, short-term storage and protection from air
Heating	Never heat with the stopper in place
Held in	Test tube rack when standing; test tube holder when handling
Tube material, size and stopper type	Confirm at enquiry

Applications

Comparing hard and soft water by shaking with soap solution and measuring lather height
The bromine water test for unsaturation, shaken safely in a closed tube
Collecting and keeping water or soil extract samples for later tests
Small-scale solvent extraction and observing the layers that separate

Care & Handling

Hold the stopper in place with a finger while shaking, since a loose stopper can be pushed out.
Match the stopper material to the contents: rubber swells in many organic solvents, and cork can absorb liquids.
Label stoppered samples on the tube, not the stopper, so the label stays with the contents.
Wash stoppers separately from tubes and let both dry before reassembling.

Why Choose LabEquip

Schools buy stoppered test tubes for shaking tests and for passing samples between classes, often with disposable Pasteur pipettes for adding reagents drop by drop. LabEquip lists them in the chemistry lab equipment range; send sizes and quantities via the LabEquip contact page.

Frequently Asked Questions

Can I heat a test tube with the stopper on?

No. Heating a sealed tube raises the pressure of the air and vapour inside, which can blow the stopper out or burst the glass. Remove the stopper before heating and replace it after cooling.

Which stopper suits organic solvents?

Rubber swells and softens in many organic solvents, so use a glass, cork or chemically resistant plastic stopper for liquids such as hexane or propanone. Rubber is fine for most aqueous solutions.

How do I carry out the soap test for hard water?

Put equal volumes of each water sample into stoppered tubes, add soap solution a little at a time and shake after each addition. Hard water needs more soap before a lasting lather forms, and it gives a scum.

Why release the stopper slowly after shaking?

Shaking can release dissolved gas or vapour, and some reactions produce gas, so pressure may have built up. Opening slowly, with the tube pointed away from people, stops liquid spraying out.

Is a stoppered tube airtight enough for storing samples?

It suits short-term storage and protects samples from dust and spills. For long-term storage or volatile liquids, a screw-cap bottle gives a more reliable seal.

How full should the tube be for a shaking test?

Fill it no more than about one-third full, so there is room for the liquids to mix when shaken. An overfilled tube mixes poorly and is more likely to leak around the stopper.

Last Updated: September 2026

Test Tube/Boiling Tube Clear Glass

Quick Answer: A Test Tube / Boiling Tube in clear glass is a basic cylindrical vessel, closed at one end, used across schools and laboratories for holding, heating, mixing, and observing small quantities of liquids and solids during practical work.

Description

The Test Tube/Boiling Tube is one of the most widely used pieces of laboratory glassware, found in nearly every chemistry, biology, and general science lab. Made from clear glass for full visibility of reactions and contents, it allows students and technicians to observe colour changes, precipitate formation, and reaction progress clearly from any angle.

Boiling tubes are typically slightly larger and more heat-tolerant than standard test tubes, making them suitable for direct heating over a burner during simple experiments, gentle warming of solutions, and small-scale reactions. The open mouth allows easy pouring, use with a stopper, or insertion of a delivery tube where a sealed setup is required.

Because it is made of laboratory glass, this tube can generally tolerate the moderate heating and common reagents typical of teaching and general chemistry work, while remaining durable enough for repeated use with proper handling and storage.

Specifications

Product Type	Test Tube / Boiling Tube (clear glass)
Material	Clear laboratory glass
Mouth Type	Open mouth, suitable for a stopper or bung where needed
Capacity	Supplied in standard laboratory sizes — confirm exact capacity at enquiry
Typical Use	Heating, mixing, sample storage, and general chemistry/biology demonstrations
Common Settings	School and college science labs, teaching laboratories

Applications

Heating small samples directly over a Bunsen burner or spirit lamp during practical demonstrations
Mixing and observing reactions where clear visibility of colour change or precipitate is important
Holding and storing small liquid or solid samples during a lab session
General biology and chemistry teaching exercises, including simple titrations and qualitative tests

Care & Handling

Use a test tube holder or tongs when heating, and always point the open mouth away from yourself and others.
Allow the tube to cool gradually after heating rather than plunging it into cold water, to reduce thermal shock.
Inspect the rim regularly for chips or cracks before use, since a damaged rim is the most common failure point.
Clean and dry thoroughly after use, and store upright in a test tube rack to prevent chipping or breakage.

Why Choose LabEquip

LabEquip supplies test tubes and boiling tubes alongside a wide range of lab glassware and general chemistry lab equipment for schools, colleges, and teaching laboratories. Our team can help you confirm the right size and quantity for your practical sessions. For bulk orders, institutional procurement, or technical questions about this product, please contact us and our team will assist promptly.

Frequently Asked Questions

What is the difference between a test tube and a boiling tube?

A boiling tube is generally slightly larger and made to better withstand direct heating, while a standard test tube is more often used for mixing, storing, and observing samples without heating.

Can this tube be heated directly over a flame?

Laboratory glass test/boiling tubes can generally tolerate the moderate direct heating typical of teaching chemistry work; always use a holder and heat gently, moving the tube through the flame rather than holding it still in one spot.

What sizes are available?

These tubes are supplied in standard laboratory sizes. Please confirm the exact length and diameter you require when you enquire.

Is a stopper included with the tube?

The tube itself has a plain open mouth suited to a standard stopper or bung; please check with our team when ordering if you need stoppers included.

How many tubes come in a pack?

Pack quantities vary — please confirm current pack size and pricing for this listing when you enquire.

How should the tubes be cleaned and stored?

Clean and dry each tube thoroughly after use, check the rim for chips, and store upright in a test tube rack to keep them organised and protected from breakage.

Last Updated: September 2026

Tubes, Delivery

Quick Answer: A delivery tube is a length of glass tubing bent to shape, such as an L or U, that carries gas from a reaction vessel to where it is collected or tested. It passes through a hole in a rubber bung or cork on the generating flask or test tube.

Carrying Gas From Flask to Jar

Almost every gas preparation in school chemistry needs a delivery tube. Hydrogen from zinc and dilute acid, carbon dioxide from marble chips and hydrochloric acid, and oxygen from hydrogen peroxide with manganese(IV) oxide all leave the flask through a bent glass tube in its bung and travel to a gas jar over water, a syringe or a test tube of limewater. The bend and length decide whether the gas can reach under a beehive shelf in a trough, up into an inverted jar or down to the bottom of an upright one.

Glass tubes are clear, so a teacher can see liquid creeping back towards a hot flask, and they resist the acids, alkalis and gases met in school work. Common forms are the right-angle L tube, the U tube and tubes bent twice for upward or downward delivery. This listing covers delivery tubes generally, so the shape, length and bore should be confirmed when ordering.

The weak point is the joint with the bung. A common cause of cuts in school laboratories is pushing glass tubing through rubber, when a tube snaps and the broken end is driven into the hand. Wetting the tube with water or glycerol, holding it close to the bung and protecting the hand with a cloth prevent most of these injuries.

Care & Handling

Take the tube out of the water before you stop heating, or cold water will be sucked back into the hot vessel and crack it.
Lubricate with water or glycerol and twist gently when inserting into a bung; never force it.
Fire-polish or inspect cut ends, because a sharp end cuts both rubber and hands.
Rinse tubes after use so acid spray and limewater deposits do not dry inside.

Applications

Collecting gases over water in a trough with a beehive shelf
Bubbling carbon dioxide through limewater to identify it
Upward or downward delivery of gases that dissolve in water, such as ammonia or hydrogen chloride
Leading gases from heated solids, such as carbon dioxide from copper(II) carbonate, into test reagents

Specifications

Item	Bent glass tubing for gas transfer
Shapes in use	L (right-angle), U and double-bend forms
Connection	Through a rubber bung or cork on the generating vessel
Gases handled	Hydrogen, oxygen, carbon dioxide and other school preparation gases
Shape, length and bore	Confirm at enquiry

Why Choose LabEquip

Schools buy delivery tubes in class quantities for gas-preparation practicals and replace them regularly as tubes break. LabEquip lists them in the chemistry lab equipment range, where they pair with vessels such as the flat bottom boiling flask; send the shapes and quantities needed through the contact page.

Frequently Asked Questions

What causes suck-back and how is it prevented?

When heating stops, the gas in the hot vessel cools and contracts, and water from the trough is pulled back along the tube into the hot glass, which can crack it. Lift the tube out of the water before removing the heat.

How do I push glass tubing into a rubber bung safely?

Wet the end of the tube with water or glycerol, wrap your hand in a cloth, hold the tube close to the bung and twist it in gently. Never push from the far end of the tube or use force.

Which delivery method suits which gas?

Gases that are only slightly soluble, such as oxygen and hydrogen, are collected over water. Soluble gases lighter than air, such as ammonia, go into an inverted jar by upward delivery, and denser ones such as hydrogen chloride into an upright jar by downward delivery.

Can glass tubing be bent in the laboratory?

Yes, soda glass tubing can be softened in a wide flame, using a fishtail attachment on the burner, and bent to a smooth curve. A narrow flame gives a kinked, weak bend, so rotate the tube evenly while heating.

Why use glass instead of rubber tubing?

Glass is rigid, transparent and resistant to most chemicals, so it holds its shape under water and shows the gas and liquid inside. Rubber or plastic tubing is often added as a flexible link between two glass sections.

How far should the tube go into the collecting jar?

For collection over water, the end only needs to sit under the mouth of the jar. For upward or downward delivery, the tube should reach nearly to the far end of the jar so the air is pushed out completely.

Last Updated: September 2026

Tubes, Culture (Disposable) Screw Thread

Quick Answer: The Tubes, Culture (Disposable) Screw Thread are single-use culture tubes with a threaded neck that takes a screw cap. Disposable screw thread culture tubes give a secure closure for cultures, specimens and prepared media, and are discarded after use instead of being washed.

Why Single-Use, Why a Screw Thread

Washing reusable culture tubes takes time, water and detergent, and any residue or surviving organism can carry over into the next culture. Disposable tubes remove that risk: each tube is used once, decontaminated and discarded. They are useful where many tubes are needed at once, where samples are infectious or where results could be affected by traces of previous contents, such as in diagnostic and food testing work.

The screw thread lets the tube be closed with a screw cap, usually plastic with a liner, which seals far better than a cotton plug or push-on cap. That makes the tube suitable for long-term storage of stock cultures on slants, for transporting specimens between labs and for media that must not dry out. Caps should be loosened before autoclaving and during aerobic incubation, then tightened for storage.

Disposable culture tubes are made of glass or plastic, and caps may be sold with the tubes or separately; the listing states neither, nor the size. Tubes for general media preparation are listed as culture media tubes, and plastic screw cap test tubes are another sealed option.

Applications

Storing slant cultures for weeks with minimal drying
Sending specimens and isolates between laboratories in sealed tubes
Diagnostic and food microbiology work where carry-over must be avoided
Large practical classes where washing hundreds of tubes is impractical

Specifications

Item	Culture tubes, disposable, screw thread finish
Use	Single use; decontaminate and discard after use
Closure	Screw cap on threaded neck
Main uses	Stock cultures, specimen transport, media storage
Material, size and caps supplied	Confirm at enquiry

Use and Disposal

Loosen screw caps half a turn before autoclaving so steam can enter and pressure can equalise.
Keep caps loose during incubation of aerobic organisms, then tighten them for storage.
Autoclave used tubes with their contents before disposal as biomedical or laboratory waste.
Find out whether the tubes are glass or plastic before heating or autoclaving empty tubes.

Why Choose LabEquip

Diagnostic labs, food testing units and large teaching labs choose disposable tubes to save washing time and avoid cross-contamination between cultures. LabEquip lists them in Biology Lab Products; ask about sizes and caps through the contact page.

Frequently Asked Questions

What does ‘disposable’ mean for these culture tubes?

They are intended for a single use. After use they are decontaminated, usually by autoclaving, and discarded instead of being washed and reused.

Why use a screw thread tube instead of a plugged tube?

A screw cap seals more tightly than a cotton plug or slip-on cap, so media dry out more slowly, spills are less likely and tubes can be transported safely.

Should the cap be tight during incubation?

For aerobic organisms keep the cap slightly loose so air can enter. Tighten it once growth is complete and the tube is going into storage.

Can disposable tubes be autoclaved?

Glass disposable tubes and many polypropylene tubes can be autoclaved, but polystyrene tubes cannot. Know the tube material before autoclaving and always loosen caps first.

Are caps included with the tubes?

Screw thread tubes are sold both with caps and without, and the listing does not state which applies here, so confirm this when you enquire.

Is it acceptable to wash and reuse disposable tubes?

It is possible with glass tubes, but it defeats their purpose. Reuse brings back the risk of residue and carry-over, and plastic ones may not tolerate washing and sterilising again.

Last Updated: September 2026