Oil Dispenser — Controlled Application of Extender Fluid
Oil Dispenser — Controlled Application of Extender Fluid
A squeeze or drip bottle used to apply oil-based extender to a faceting lap during polishing
An oil dispenser is a squeeze or drip bottle used to apply oil-based extender fluid to a faceting lap during polishing. The dispenser allows controlled delivery of lubricant to maintain an even film over diamond paste or compound, preventing the abrasive from drying and ensuring consistent cutting action. Common extender oils include light mineral oil and synthetic formulations developed specifically for lapidary use. The dispenser is a standard accessory in faceting setups and is refilled as needed during long polishing sessions.
Why controlled dispensing matters
The behaviour of diamond paste on a faceting lap depends on the balance between abrasive density and carrier fluid. Too dry, and the paste dries out, the diamond particles cake, and cutting action becomes inconsistent. Too wet, and the carrier oil floods the lap, washes the diamond charge into the gutters, and reduces effective abrasive contact with the workpiece. The dispenser allows the cutter to maintain the optimal balance through small, frequent additions of extender fluid.
The volume of fluid added per drop is small — typically a few microlitres — and the cutter dispenses across the working radius of the lap so that the entire cutting surface remains evenly lubricated. Skilled faceters develop a routine of light, periodic dispensing rather than infrequent large additions.
Dispenser types
Several styles of dispenser are common. Plastic squeeze bottles with fine-tipped nozzles are inexpensive, durable, and easy to operate one-handed. Glass dropper bottles with rubber bulb caps offer precise drop control. Some cutters prefer pen-style applicators with a feed mechanism that allows continuous, slow application; these are less common but well-regarded for specific applications.
The choice depends on the cutter's preferences, the volume of work, and the fluid being dispensed. Some fluids are more viscous than others and dispense better through wider nozzles; some fluids degrade plastic bottles and require glass containers.
Maintenance and replacement
Dispensers are simple and durable but require periodic cleaning to prevent accumulation of contamination. Diamond particles that backflow into the dispenser can clog nozzles or mix with fresh fluid, contaminating subsequent applications. Periodic flushing with clean solvent and refilling with fresh fluid maintains performance.