12 mm LDPE Test Tube Stoppers — White, Plug-In Friction Fit, 1000/Bag (300-2912-W20)
These white low-density polyethylene (LDPE) stopper caps are engineered for standard 12 mm OD test tubes — including 12 × 75 mm and 12 × 100 mm glass and polystyrene culture tubes — and are compatible with BD® Vacutainer-style collection tube formats in the same diameter. Supplied non-sterile in 1000/Bag bulk packaging, part number 300-2912-W20 delivers the plug-in friction-fit seal and flexible LDPE construction that high-volume clinical chemistry, microbiology, and specimen archiving workflows depend on. The white stopper surface provides the highest-contrast background for adhesive and printed barcode labels, making these caps the preferred choice for laboratories that rely on label-based specimen identification rather than stopper color alone.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number (MPN) | 300-2912-W20 |
| Tube OD | 12 mm |
| Compatible Tube Formats | 12 × 75 mm and 12 × 100 mm glass and PS culture tubes; BD® Vacutainer-compatible 12 mm formats |
| Cap Style | Stopper — plug-in friction fit |
| Material | Low-Density Polyethylene (LDPE) |
| Color | White |
| Temperature Range | -20°C to +60°C |
| Sterility | Non-Sterile |
| Pack Size | 1000/Bag |
| BPA / Phthalates | BPA-free; no phthalate plasticizers |
| Country of Origin | USA |
Applications
- Microbiology culture tube capping: Seals TSB, BHI, LB broth, and other culture media tubes during incubation; LDPE retains flexibility and seal engagement at 37°C
- Specimen tube archiving: Prevents evaporation of serum, plasma, and urine during refrigerated and frozen storage; LDPE remains pliable at -20°C for repeated frozen-archive access
- Clinical tube color-routing systems: White stoppers slot into CLSI-convention color-coded specimen-routing programs; white's high contrast also supports primary label-based routing where stopper color is secondary
- Cell culture and virus propagation: Stopper-style fit caps suspension culture and virus propagation vessels while resisting contamination
- Pneumatic tube transport: LDPE flex retention maintains the friction seal through the acceleration and deceleration forces of clinical pneumatic transport systems
- Clinical chemistry and hematology: Caps 12 mm OD tubes across high-throughput chemistry and hematology specimen workflows requiring bulk, low-cost capping solutions
Compatibility
These stoppers are designed to fit standard 12 mm outer-diameter test tubes, the most widely used diameter across general laboratory and clinical tube formats. Compatible tube types include standard 12 × 75 mm and 12 × 100 mm glass and polystyrene culture tubes, as well as BD® Vacutainer-compatible collection tube sizes and common polypropylene clinical test tube formats in the 12 mm OD class. Because the 12 mm diameter represents the broadest compatibility range in the Caplugs® Evergreen stopper series, these caps are typically ordered in the highest volumes for clinical and research programs. Always verify the outer diameter of your specific tube lot before transitioning from an existing stopper supply, as nominal tube dimensions can vary slightly by manufacturer.
Chemical Resistance
| Reagent / Condition | Compatibility |
|---|---|
| Aqueous buffers and saline | Excellent |
| Serum and plasma | Excellent |
| Urine | Excellent |
| Broth media (TSB, BHI, LB) | Excellent |
| Dilute acids and bases | Good |
| Ethanol and aqueous alcohols | Good — short-term contact; prolonged exposure not recommended |
| Chlorinated solvents (chloroform, DCM) | Not recommended |
| Aromatic solvents (toluene, xylene) | Not recommended |
| Frozen storage (-20°C) | Compatible — LDPE retains flexibility at sub-zero temperatures |
| Incubation temperature (37°C) | Compatible — seal engagement maintained within rated temperature range |
Quality & Procurement
Made in USA, these Caplugs® Evergreen stoppers are manufactured from BPA-free, phthalate-free LDPE resin, ensuring chemical inertness to serum, plasma, urine, and broth media during storage. LabSupplies.com is an authorized Caplugs® Evergreen dealer and ships from USA inventory, typically same business day for stocking items. Tiered pricing is available for institutional purchasing programs, hospital systems, and grant-funded laboratories requiring high-volume tube capping solutions.
Frequently Asked Questions
Are these tube stoppers sterile?
No — the 300-2912-W20 stoppers are supplied non-sterile in 1000/Bag bulk packaging. For workflows requiring sterile closures, evaluate gamma-irradiated options or sterilize by appropriate method validated for LDPE.
What tube sizes do these stoppers fit?
These stoppers are designed for tubes with a 12 mm outer diameter, including standard 12 × 75 mm and 12 × 100 mm glass and polystyrene culture tubes, as well as BD® Vacutainer-compatible collection tube formats in that diameter. Always confirm the OD of your specific tube lot before switching from your current stopper supply.
Can these stoppers be used for frozen specimen storage?
Yes. LDPE retains its flexibility down to -20°C, so the friction-fit seal remains intact and the stopper can be removed and reinserted without fracture during frozen-archive access — a key advantage over stiffer plastics for cold-storage tube management.
Why choose white stoppers over other colors?
White provides the highest-contrast background for adhesive and printed barcode labels, making it the preferred stopper color for laboratories that route specimens primarily by label rather than by stopper color. White also participates in CLSI-convention color-coding programs where white is an assigned specimen-type designator.