- Solid Cone Stopper
- Flat Head
- Size 10/19 joint
- Made of high-quality borosilicate glass
OVERVIEW:
The GWSI 10/19 Penny Head Solid Cone Glass Stopper is a small-joint sealing component designed for compact laboratory vessels — test tubes, small flasks, sample vials, and miniaturized apparatus with 10/19 standard taper sockets. Fabricated from premium borosilicate 3.3 glass, it provides excellent chemical inertness and high thermal shock resistance for dependable performance with aggressive reagents and temperature variations. The flat penny head offers a secure grip even on tiny vessels where finger clearance is minimal, and the solid cone construction delivers a uniform ground surface for consistent, leak-tight sealing.
HISTORY:
The 10/19 joint size was introduced as part of the standardized ground joint system to serve the smallest category of laboratory glassware — typically vessels under 50 ml capacity where even a 10/19 stopper would be oversized and unwieldy. As microscale chemistry techniques gained traction in teaching and research labs during the late 20th century, the demand for well-fitting miniature stoppers grew accordingly. The penny head design proved particularly valuable at this scale because the flat disc provided enough surface area to grasp securely without adding excessive height or weight to small, top-heavy assemblies.
APPLICATIONS:
– Pharmaceutical discovery labs — sealing small reaction vials and microscale flasks during high-throughput screening campaigns
– Biotech assay labs — capping small reagent tubes and sample containers during sensitive analytical workflows
– industrial QC labs — closing small volumetric flasks and sample vials during trace-level analysis
– University microscale organic lab — stoppering small flasks and test tubes during green chemistry practicals
– College teaching labs — sealing test tubes, small reagent bottles, and demonstration apparatus during practical sessions
– School chemistry labs — safe containment of small chemical quantities in test tubes and miniature storage vessels
– Research institutes — sealing NMR tubes, small Schlenk vessels, and microscale reaction assemblies during air-sensitive work
– Educational institutes — training students on microscale apparatus assembly, joint care, and proper stopper technique
MANUFACTURING PROCESS:
GWSI produces each 10/19 penny head solid cone stopper by melting high-purity borosilicate 3.3 glass at temperatures above 1,600 °C, then forming the miniature solid cone and flat penny head through precision automated molding for tight dimensional control at this small scale. The ground cone surface is lapped to exact 10/19 taper geometry using ultra-fine abrasive compounds to achieve a smooth, uniform seal with any matching socket. Every stopper is then annealed in a controlled lehr oven to relieve all internal thermal stress and ensure dimensional stability.
TESTING PROCESS :
Each stopper begins with a meticulous manual inspection under magnification where technicians verify cone taper accuracy, surface finish quality, penny head flatness, and overall dimensional conformity to the 10/19 specification. A Polariscope polarization stress test then confirms zero residual strain throughout the glass body — any stress indication leads to immediate rejection. Fit testing is performed by mating each stopper with a certified 10/19 master gauge to verify a uniform, leak-tight seal under light hand pressure.
PRINTING PROCESS :
Size identification markings are applied through precision screening with glass enamels — high-resolution ceramic inks formulated for fine-detail marking on small borosilicate surfaces. The stoppers are then fired in high-temperature kilns where the ceramic layer sinters and fuses permanently into the glass matrix, producing crisp, legible markings that withstand solvents, acids, and repeated autoclave sterilization without fading.
PACKAGING PROCESS :
Every finished stopper passes through a final cosmetic sorting stage where inspectors reject any unit with surface blemishes, taper irregularities, or head defects. Approved stoppers are then individually wrapped in shock-absorbing bubble wrap or nested in compartmentalized trays with small-cell dividers to prevent contact damage during transit and packed in heavy-duty double-wall corrugated export boxes for safe domestic and international delivery.
MAINTENANCE & SAFETY :
– Clean gently with warm water and a mild non-ionic lab detergent; use a soft cloth — the smaller ground surface is more susceptible to visible scratching that can compromise the seal.
– Autoclave at 121 °C — this autoclavable lab glass retains full hydrolytic resistance and dimensional accuracy through repeated sterilization cycles.
– Store in a labelled compartment or small-parts tray to prevent the miniature stopper from rolling off benchtops or getting lost among larger glassware.
– Insert with minimal force — the 10/19 joint requires very light pressure; if it does not seat smoothly, check for debris or a mismatched socket rather than pushing harder.
– Free stuck stoppers by warming the outer socket with warm water to expand it slightly — never apply twisting force, which can easily snap the small cone stem.
– Inspect under magnification periodically for fine scratches or chips; at this scale, even minor surface damage can cause leaks and warrants immediate replacement.
Manufactured by GWSI Glass Lab — Ambala, Haryana, India (The Science City)