The Technical Vault
By SOSCleanroom
KIMBLE 34505-99
One End Sealed
90 mm Length
0.20 mm Wall
Borosilicate Glass
100 Tubes / Vial
2,000 / Case
KIMBLE 34505-99: a sealed-end capillary for observing solid-to-liquid transitions
KIMBLE® KIMAX® 34505-99 is a borosilicate glass melting-point capillary supplied with one end factory-sealed. The tube is intended for use in laboratory melting-point determination procedures where a small solid sample is heated and its transition to a liquid is observed.
DWK specifies a 90 mm finished length, a 0.20 mm glass wall thickness, and a published diameter range of 1.5–1.8 mm. Each vial contains 100 capillaries, and a complete manufacturer case contains 20 vials.
Because the tube is already closed at one end, a user can introduce a prepared sample through the remaining open end and settle it into the sealed portion. The capillary then functions as a small glass sample holder during the controlled heating and observation process.
Operations takeaway: A melting-point capillary provides sample containment, not temperature measurement or instrument calibration. Accurate results depend on the sample, capillary geometry, heating conditions, temperature-measuring system, and laboratory method. For strict instrument-fit specifications, resolve the manufacturer's conflicting ID/OD descriptions before use.
Specifications (SKU controls for RFQs, SOPs, and receiving)
- Manufacturer: DWK Life Sciences
- Brand: KIMBLE® / KIMAX®
- Catalog Number: 34505-99
- Product Type: Melting point capillary tube
- Material: Borosilicate glass
- Current Online Glass Description: Borosilicate glass 3.3
- Historical Glass Description: 51-expansion borosilicate; discrepancy requires manufacturer clarification if composition is critical
- End Configuration: Sealed at one end; opposite end open
- Finished Length: 90 mm
- Nominal Wall Thickness: 0.20 mm
- Published Diameter Range: 1.5–1.8 mm
- Diameter Label: Listed as ID on current DWK page; historical Kimble catalog identifies the same range as OD
- Factory Sealing: One end sealed before supply
- Open End: Remains accessible for introducing the sample
- Vial Quantity: 100 individual capillaries
- Case Quantity: 20 vials
- Total Case Contents: 2,000 capillary tubes
- Intended Use: Melting-point determination of solid samples
- Related Configurations: 34500-99, 34502-99, and 34507-99
Receiving rule: DWK's individual SKU table shows a quantity of 20 because the manufacturer sells 20 vials per case. The family packaging description confirms 100 tubes in each vial. The complete case therefore contains 2,000 tubes, not 20.
Critical dimensional distinction: inside diameter versus outside diameter
The current DWK North American product page identifies 1.5–1.8 mm as ID for 34505-99. Earlier KIMBLE/KIMAX catalog tables identify 1.5–1.8 mm as OD for the same manufacturer catalog number, length, and wall thickness.
Inside diameter and outside diameter are distinct engineering measurements. A capillary holder that must accommodate a specified maximum outside diameter cannot be qualified solely from an uncertain inside-diameter label.
| Source description |
Published designation |
Action |
| Current DWK web specification |
ID: 1.5–1.8 mm |
Retain as the current web label; confirm if critical |
| Historical Kimble catalog |
OD: 1.5–1.8 mm |
Recognize the inconsistent labeling |
| Both references |
Wall: 0.20 mm; length: 90 mm |
Use these confirmed dimensions |
For a uniform cylindrical tube, inside and outside dimensions are related by the two wall thicknesses. However, deriving an assumed bore from inconsistent catalog descriptions is not equivalent to obtaining a confirmed manufacturer tolerance.
Specification-control checkpoint: Request DWK confirmation of the actual ID and OD if the capillary must fit a fixed-width instrument slot, if a validated internal sample bore is required, or if those dimensions are part of a controlled purchasing specification. Do not invent a numeric tolerance for either dimension.
Borosilicate glass: current product-family terminology versus older KIMAX documentation
DWK's current online melting-point capillary family describes these tubes as manufactured from borosilicate glass 3.3. Older Kimble/KIMAX catalog literature for the family describes 51-expansion borosilicate glass and references USP Type I and ASTM E438 Type I, Class B material requirements.
These descriptions refer to different glass expansion categories and should not be treated as interchangeable. DWK's glass-properties guide distinguishes 3.3-expansion borosilicate glass from other borosilicate compositions and their respective material classifications.
- Confirmed Glass Family: Borosilicate glass.
- Current Web Listing: Borosilicate glass 3.3.
- Historical Literature: 51-expansion borosilicate glass.
- Thermal Expansion: Exact SKU-level formulation should be confirmed before assigning a coefficient.
- ASTM Glass Classification: Do not automatically assign one classification when source descriptions conflict.
- USP Glass Material Designation: Historical reference does not establish a current lot certificate or finished-product pharmacopoeial compliance.
- Melting-Point Method Compliance: Separate from the chemical composition of the glass.
Material qualification: The current web listing and historical catalog do not completely agree. If the exact glass composition, expansion coefficient, ASTM classification, or chemical-extractables behavior is material to the application, request current product-specific confirmation from DWK before treating either description as certified.
Review DWK's Glass Types & Properties technical guide
Melting-point determination: what the capillary allows the laboratory to observe
A melting-point determination measures the temperature or range of temperatures over which a prepared solid sample undergoes a solid-to-liquid transition. The laboratory may observe the first sign of melting, the point at which the sample has completely melted, or other method-defined transitions.
For many crystalline solids, the observed melting behavior can support identification and purity assessment. Impurities may depress or broaden the melting range, but the relationship depends on the substance and the nature of the impurities.
- Solid Sample: A small amount of appropriately prepared material is placed inside the tube.
- Sealed End: Retains the sample during the selected observation method.
- Heat Transfer: The apparatus or bath provides controlled heating to the glass and sample.
- Observation: The operator or instrument identifies relevant melting changes.
- Temperature Measurement: Performed by the calibrated instrument or thermometer, not by the tube itself.
- Recorded Result: Determined by the analytical procedure's rules for onset, completion, or melting range.
Interpretation rule: The observed melting range is a property of the sample under the selected measurement conditions. The capillary does not carry an independent temperature calibration, purity certification, or guaranteed measurement uncertainty.
Sample preparation and capillary loading technique
Sample preparation is a major variable in melting-point measurement. Differences in moisture, particle size, sample depth, packing density, and contamination can change the apparent melting behavior or reduce repeatability.
The capillary is filled from its open end, with the sample collected near the factory-sealed tip. The packed sample height should follow the applicable analytical method or instrument procedure.
- Check the tube: Confirm that the sealed tip is intact and the tube is not chipped or cracked.
- Prepare the solid: Dry, crush, or homogenize the sample where required by the approved method.
- Transfer carefully: Introduce a small amount of material through the open end.
- Move material toward the tip: Use the approved technique to settle the sample into the closed end.
- Control the depth: Establish the prescribed packed-sample column height without overfilling.
- Prevent contamination: Use clean tools and avoid contact with other substances.
- Check sample distribution: Avoid obvious gaps, loosely packed regions, or inconsistent sample preparation.
- Mount correctly: Place the filled tube in the appropriate holder without applying excessive force.
Standardization tip: When comparing results across operators or batches, keep sample preparation, approximate packed height, capillary type, apparatus settings, and temperature-reading procedure consistent.
Heating rate, sample size, and observed melting range
The rate of heating can influence the apparent melting point because the indicated apparatus temperature and actual sample temperature may not remain identical during rapid temperature changes.
Many laboratory procedures call for approaching the expected melting range with controlled heating rather than increasing temperature rapidly through the transition. The exact heating program should be selected according to the method, apparatus, and substance being analyzed.
- Heating Rate: Use the rate prescribed by the analytical method.
- Sample Height: Excessive packed depth can create temperature gradients or alter observed behavior.
- Capillary Position: Position correctly relative to the heating block, bath, or temperature sensor.
- Temperature Calibration: Verify the apparatus according to the laboratory's measurement-control requirements.
- Replicate Tests: Use additional prepared samples when the method requires confirmation or repeatability checks.
- Result Reporting: Record the observed range and method conditions rather than assigning a universal instrument accuracy to the tube.
No manufacturer-specific heating rate, sample loading depth, or apparatus temperature limit is established for the 34505-99 tube in the reviewed product listing. Those settings belong to the selected method and instrument.
Bath-based melting-point apparatus: why the 90 mm length matters
DWK describes its melting-point capillaries as long enough for the open end to extend well above the surface of a suitable heating bath. This arrangement helps prevent heating-bath liquid from entering the tube and contacting the prepared sample.
The factory-sealed 34505-99 is 90 mm long, while the corresponding open-at-both-ends 34500-99 is 100 mm long. The manufacturer explains that the length is reduced by approximately 10 mm when a tube is sealed.
- Sealed Tip: Positioned in the appropriate observation or heating region.
- Open End: Maintained above the bath surface as required by the apparatus.
- Immersion Depth: Controlled by the selected bath, capillary support, and laboratory procedure.
- Bath Medium: Selected for the required temperature range and chemical safety.
- Temperature Measurement: Conducted using the approved thermometer or instrument arrangement.
- Handling: Avoid direct contact with hot bath liquid and use appropriate glass handling tools.
Bath-use checkpoint: A 90 mm length is not a universal immersion-depth specification. Confirm that the open end remains above the actual bath level and that the entire assembly is suitable for the procedure.
One end sealed versus both ends open: choosing the correct capillary
DWK supplies the KIMAX melting-point capillary family in two primary end configurations. A sealed-end tube is ready to accept a sample through its open end. A tube open at both ends may require preparation before use in a method that calls for a closed sample tip.
| Feature |
34505-99 |
34500-99 |
| End configuration |
Sealed at one end |
Open at both ends |
| Supplied length |
90 mm |
100 mm |
| Wall thickness |
0.20 mm |
0.20 mm |
| Published diameter range |
1.5–1.8 mm* |
1.5–1.8 mm* |
| Additional user sealing |
Not needed for closed-tip use |
May be needed by the method |
| Manufacturer case |
2,000 tubes |
2,000 tubes |
*The published 1.5–1.8 mm range has inconsistent ID/OD labeling across manufacturer information and historical references. Seek confirmation if a specific internal or external dimension is required.
The open-ended configuration should not be presented as identical to a factory-sealed tube. Additional sealing can change finished length and requires appropriate procedures for heating and handling glass.
KIMAX melting-point capillary family: verified size and construction comparison
The four related DWK catalog numbers differ in end configuration, finished length, and published diameter and wall specifications. The narrow-bore models are specifically described by DWK as designed from requirements contained in the United States Pharmacopeia.
| DWK SKU |
End Configuration |
Length |
Diameter Range |
Wall |
| 34500-99 |
Both ends open |
100 mm |
1.5–1.8 mm* |
0.20 mm |
| 34502-99 |
Both ends open |
100 mm |
0.8–1.1 mm ID |
0.25 mm |
| 34505-99 |
One end sealed |
90 mm |
1.5–1.8 mm* |
0.20 mm |
| 34507-99 |
One end sealed |
90 mm |
0.8–1.1 mm ID |
0.25 mm |
*The 1.5–1.8 mm range has conflicting ID/OD descriptions. For the two narrower-bore models, DWK's current tables specifically publish an ID range of 0.8–1.1 mm.
Pharmacopoeial selection note: DWK explicitly identifies the 34502-99 and 34507-99 narrower-bore designs with USP-related requirements. This does not establish that 34505-99 has the same narrow bore or that any capillary provides independent compliance with an entire pharmacopoeial test method.
Borosilicate glass compatibility and sample-related limitations
Borosilicate glass is widely used in laboratory applications because of its chemical durability and thermal behavior. DWK's general glass technical guidance identifies broad resistance to water, many acids, salt solutions, and organic solvents, with important exceptions.
For this capillary family, exact material-composition claims remain subject to the discrepancy between current and historical documents. Therefore, composition-specific chemical or thermal values should not be applied as finished-product ratings without current manufacturer confirmation.
- Water and Many Organic Solvents: Borosilicate glass generally offers favorable chemical durability.
- Many Common Acids: Usually favorable, subject to composition and conditions.
- Hydrofluoric Acid: Attacks silica-based glass and requires a different material strategy.
- Hot Concentrated Phosphoric Acid: Can corrode borosilicate glass.
- Strong Alkali: Can attack glass, particularly under elevated-temperature conditions.
- Sample Decomposition: Materials that decompose, react, or evolve gas during heating require method-specific evaluation.
- Glass Temperature Rating: No finished-capillary operating limit is established by the reviewed SKU listing.
The chemical compatibility and analytical suitability of the actual sample must be determined under the laboratory's method and safety procedures.
Sample contamination and handling controls
Melting-point observations can be influenced by contamination introduced during sample handling. Dirty tools, residual substances, moisture, or cross-contact with another sample may change the observed temperature range or create inconsistent results.
- Clean Transfer Tools: Avoid carryover between different substances.
- Dry Sample Preparation: Follow the method's requirements for sample moisture and preparation.
- Protected Storage: Keep unused capillaries in their vial until needed.
- Visual Inspection: Reject capillaries containing visible foreign matter, chips, or damage.
- Handling: Avoid unnecessary contact with the open tube end or sample-contact surfaces.
- Sample Identification: Associate each prepared capillary with the correct specimen and analytical record.
The manufacturer does not establish a specific particle cleanliness limit, sterile designation, or low-extractables specification for the finished 34505-99 capillary in the reviewed product information.
Sterility, cleanroom suitability, and thermal-processing boundaries
KIMBLE 34505-99 is presented by DWK as a laboratory melting-point capillary, not as a sterile medical capillary or a certified cleanroom consumable. No supplied-sterile designation, validated sterilization cycle, or ISO cleanroom classification was identified for this SKU.
The finished product is a thin-walled glass tube. The material's general thermal resistance does not establish safe direct-flame use, universal autoclave compatibility, or a maximum instrument temperature for the individual capillaries.
- Supplied Sterility: Not established.
- ISO Cleanroom Cleanliness: No SKU-specific classification identified.
- Particle or Ionic Limits: No finished-product specification identified.
- Validated Autoclave Cycle: Not identified in the reviewed product record.
- Maximum Operating Temperature: No finished-capillary value published in the reviewed record.
- Regulated Application: Requires confirmation of method and material requirements, including any necessary product documentation.
Qualification boundary: A capillary's use in melting-point determination is not proof of sterile, medical, GMP, or pharmacopoeial qualification for every use. Do not add these certifications to the product description without applicable manufacturer records.
Thin-wall glass safety: breakage, burns, and disposal
Capillary tubes are fragile glass products, and melting-point testing introduces additional hazards from heat, the selected sample, and possibly heated bath liquids. Follow the laboratory's safety procedure and the apparatus manufacturer's instructions.
- Inspect Before Use: Do not use capillaries with visible cracks, chipped ends, or damaged factory seals.
- Avoid Excessive Force: Do not force the tube into a holder or support.
- Heated Glass: Allow sufficient cooling before touching or discarding.
- Bath Fluids: Follow the chemical and temperature safety precautions for the selected heating medium.
- Sample Hazards: Evaluate decomposition, toxicity, vapor, pressure, and reactivity concerns for the solid under test.
- Broken Glass: Collect with suitable tools and dispose of in a puncture-resistant designated laboratory container.
- Used Capillaries: Treat as contaminated laboratory waste when the sample or method requires it.
Glassware safety: Never assume a thin-walled glass capillary can be handled like robust laboratory tubing. Direct heating, impact, abrupt thermal changes, and chemical attack can increase breakage risk. Follow the approved analytical procedure.
Packaging, receiving, and inspection checklist
DWK packages the melting-point capillary family in vials containing 100 tubes each. The manufacturer case includes 20 vials, totaling 2,000 capillary tubes. Receiving procedures should verify the manufacturer's package configuration before releasing the material for laboratory use.
- Verify Manufacturer SKU: Confirm KIMBLE 34505-99 against the purchase order.
- Confirm Configuration: Verify that the tubes are supplied sealed at one end.
- Verify Length: Confirm the specified 90 mm finished configuration.
- Verify Wall: Confirm the 0.20 mm specification.
- Check Package Quantity: Verify 100 capillaries per vial and 20 vials per case.
- Inspect Vials: Check for cracks, breakage, open packaging, or other damage.
- Inspect Representative Tubes: Look for damaged tips, fragments, deformation, or contamination.
- Confirm Critical Geometry: Obtain current ID/OD confirmation if it is part of the approved purchasing specification.
- Record Material Information: Retain manufacturer identification and any applicable glass-composition documentation.
- Record Disposition: Accept, quarantine, or reject according to the laboratory's receiving controls.
Purchasing checkpoint: A 100-tube vial is an inner package. The manufacturer case contains 20 such vials. Confirm whether a supplier offers an authorized smaller selling unit before pricing or listing this product as a single 100-count vial.
Storage, handling, and inventory control
Unused capillaries should be protected from impact and contamination and kept in suitable packaging until required. The manufacturer vial format supports controlled dispensing of fragile individual tubes.
- Preserve Packaging: Keep capillaries protected in the original vial or appropriate laboratory storage container.
- Prevent Damage: Avoid impact, crushing, or bending stresses during handling.
- Control Contamination: Prevent dust, chemical residues, and cross-contact with samples.
- Separate Configurations: Store open-ended and sealed-ended variants under distinct identifiers.
- Label Packages: Retain the exact SKU and the 100-tube inner pack designation.
- Keep Records: Maintain receiving and issue records according to the laboratory's procedures.
The reviewed DWK listing does not establish a finished-product expiration date or special temperature and humidity limits for storage. Use the applicable laboratory inventory and glassware-handling procedures.
Technical FAQs
Are KIMBLE 34505-99 capillaries sealed at one end?
Yes. They are supplied factory-sealed at one end, with the opposite end open for sample loading.
How long are the finished tubes?
DWK specifies a 90 mm finished length for 34505-99.
What is the wall thickness?
The manufacturer specifies a 0.20 mm glass wall.
Is the 1.5–1.8 mm dimension the inside or outside diameter?
DWK's current online table labels the range as ID, while historical KIMBLE documentation describes 1.5–1.8 mm as OD. Obtain current manufacturer confirmation where the distinction affects equipment fit or method compliance.
How many capillaries are included in a case?
There are 100 tubes per vial and 20 vials per manufacturer case, totaling 2,000 capillaries.
Does DWK's quantity of 20 mean 20 tubes?
No. The current product-family description identifies 20 vials per case, each containing 100 tubes.
What is the difference between 34505-99 and 34500-99?
34505-99 is supplied sealed at one end and is 90 mm long. 34500-99 is open at both ends and is 100 mm long. Both have a published 0.20 mm wall thickness.
Which version has the smaller internal diameter?
DWK identifies 34502-99 and 34507-99 as narrower-bore variants with a published ID of 0.8–1.1 mm and a 0.25 mm wall thickness.
Is 34505-99 specifically designed for USP melting-point requirements?
DWK specifically connects the narrower-bore 34502-99 and 34507-99 designs to USP-related requirements. Do not assume the same statement applies to 34505-99 without manufacturer and method confirmation.
Is the glass borosilicate 3.3 or 51-expansion borosilicate?
The current DWK product-family page states borosilicate glass 3.3, while historical KIMBLE documentation describes 51-expansion borosilicate. Confirm the currently supplied material with DWK if glass composition is critical.
Do these tubes measure temperature?
No. They are glass sample holders. Temperature is measured by the melting-point apparatus or a separately selected calibrated thermometer.
Can I reuse a capillary after melting a sample?
The product is generally used as a disposable sample holder in melting-point procedures. Do not assume a used tube remains suitable or uncontaminated for another test. Follow the laboratory method and waste procedure.
Are the capillaries sterile or cleanroom certified?
No supplied-sterile designation or ISO cleanroom cleanliness certification is established by the reviewed DWK listing.
Can the tubes be placed in a heated liquid bath?
DWK describes the length as intended to keep the open end above a heating bath's surface. Actual suitability depends on the apparatus, bath medium, temperature, and test procedure.
What is the maximum melting-point temperature?
The reviewed manufacturer record does not publish a product-specific maximum measurement temperature. Follow the approved instrument and capillary specifications for the method.
Why purchase KIMBLE melting-point capillaries from SOSCleanroom
- Exact SKU identification: SOSCleanroom helps laboratories distinguish one-end-sealed and open-ended capillary configurations.
- Dimension control: Request assistance confirming critical inside and outside dimensions when instrument fit is important.
- Manufacturer documentation: Our team can help obtain available technical details and clarification of glass-material specifications.
- Packaging accuracy: Confirm the manufacturer's 100-tube vial and 20-vial case configuration before purchasing.
- Laboratory procurement: Source specialty glassware and related laboratory consumables through SOSCleanroom.
- Responsive support: Contact our team for quotes, availability, and product sourcing assistance.
Manufacturer documentation and authoritative technical references
The current DWK product listing was used to establish the sealed-end configuration, 90 mm length, 0.20 mm wall, 1.5–1.8 mm published diameter range, and 20-vial case. The family description confirms 100 tubes per vial. Historical catalog descriptions differ on the ID/OD label and glass expansion designation, so these details remain subject to manufacturer clarification.
General manufacturer glass technical references are educational resources and should not be interpreted as product-specific certificates or as authorization to use a capillary outside the approved method.
If you have any questions please email us at Sales@SOSsupply.com or give us a call at (214) 340-8574.
For additional product guidance, use the SOSCleanroom AI ChatBot or contact our team for manufacturer documentation assistance.
Technical insight: Melting-point performance depends on controlled sample preparation, capillary dimensions, temperature calibration, heating conditions, and correct observation. A factory-sealed glass tube provides a sample holder; its material and dimensional specifications should be verified whenever the analytical procedure requires them.
Last updated: October 28, 2026
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