- 500 ml funnel with PTFE key stopcock
- Made from high-quality 3.3 borosilicate glass
- Includes interchangeable polypropylene stopper
- 29/32 socket size
- Low temperature gradient – can withstand high temperatures and thermal shocks*
- Superior chemical durability
- Compliance with IS 1575.
- Cylindrical shape
OVERVIEW:
The GWSI 500 ml Graduated Dropping Funnel with Rota flow PTFE Stopcock is a semi-micro precision tool built for reactions where reagent volumes are small and accuracy is non-negotiable. Formed from premium borosilicate 3.3 glass, it delivers high thermal shock resistance and complete chemical inertness against concentrated acids, halogenated solvents, and strong bases. Its ultra-compact profile fits neatly onto mini-scale glassware assemblies, while the interchangeable ground joint socket provides a reliable, leak-tight connection in any standard taper configuration.
HISTORY :
The need for small-volume dropping funnels grew out of the microscale chemistry movement that gained momentum in the 1980s, led by educators seeking to reduce chemical waste and improve student safety. Traditional funnels were far too large for the 50–500 ml reaction scales these methods required. Glassware makers responded by miniaturizing every component — funnel body, graduated stem, and stopcock bore — while maintaining the same volumetric accuracy standards used in full-size Class A volumetric glassware and Class B glassware.
APPLICATIONS :
– Pharmaceutical micro-synthesis labs — dropwise addition of expensive or scarce intermediates during early-stage drug discovery
– Biotech assay development — controlled delivery of colorimetric reagents in microplate-based protocols
– Industrial specialty chemical labs — additive metering for small-batch coating, adhesive, and ink formulations
– University microscale organic labs — modern green chemistry curricula using reduced solvent and reagent volumes
– College analytical chemistry labs — small-volume titrations and standardization procedures
– School advanced practical labs — safe, low-waste demonstrations of reaction kinetics and equilibrium shifts
– Research institutes — trace-level synthesis, catalysis screening, and isotope-labeled compound preparation
– Educational institutes — training students on Class A volumetric glassware techniques using minimal chemical quantities
MANUFACTURING PROCESS:
GWSI fabricates each 500 ml dropping funnel by melting high-purity borosilicate 3.3 glass at over 1,600 °C, then shaping the miniature bulb and stem through a combination of master hand-blowing for fine wall control and automated precision molding for repeatable dimensional accuracy. The miniature Rota flow stopcock bore is tooled to tight tolerances, and the socket joint is finished via ceramic glass fusing to ensure an exact taper match. Every piece is then annealed in a controlled lehr oven cycle to relieve all internal thermal stress and lock in long-term structural stability.
TESTING PROCESS :
Each funnel starts with a meticulous manual inspection covering wall uniformity, stem bore diameter, joint fit, and graduation readability at the fine 500 ml scale. A Polariscope polarization stress test then confirms zero residual strain across the entire glass body — any birefringence triggers immediate rejection. Volumetric graduation accuracy is verified on the basis of ISO and DIN standards using manual or automatic testing machines, and NABL gravimetric calibration certifies the scale to its declared Class A or Class B tolerance.
PRINTING PROCESS :
Fine graduation lines and volume numerals are applied through precision screening using glass enamels — ceramic inks formulated specifically for high-resolution marking on small-diameter borosilicate surfaces. The funnels are then fired in high-temperature kilns, where the ceramic ink permanently fuses into the glass matrix, producing crisp, fade-proof markings that survive aggressive solvents and repeated autoclave sterilization.
PACKAGING PROCESS:
Before dispatch, every 500 ml funnel goes through a final cosmetic sorting inspection to eliminate any unit with surface blemishes, wall irregularities, or joint imperfections. Approved funnels are individually wrapped in shock-absorbing bubble wrap, nested in custom-fit cardboard inserts, and sealed inside heavy-duty double-wall corrugated boxes for safe domestic and export transit.
MAINTENANCE & SAFETY :
– Rinse immediately after use with warm deionized water, then wash with a mild lab-grade detergent using a soft micro-brush for the narrow stem.
– Autoclave at 121 °C — this autoclavable lab glass withstands repeated cycles without any loss of hydrolytic resistance or dimensional accuracy.
– Clear the PTFE stopcock bore after handling viscous or crystallizing reagents by flushing with a compatible solvent to maintain smooth, consistent rotation.
– Store in a padded glassware drawer or dedicated small-parts tray to prevent the compact socket joint from rolling or falling.
– Inspect the PTFE plug before every session for signs of deformation or chemical attack; a worn plug compromises drop-rate precision.
– Avoid mechanical shock — the smaller wall thickness of semi-micro glassware demands careful handling to prevent chipping at the joint and stem tip.
Manufactured by GWSI Glass Lab — Ambala, Haryana, India (The Science City)