Oil Bottle — Dispensing Extender Fluid on the Faceting Lap
Oil Bottle — Dispensing Extender Fluid on the Faceting Lap
A small squeeze or dropper bottle for applying lubricant to maintain diamond paste during polishing
An oil bottle is a small squeeze or dropper bottle used to dispense extender oil onto a faceting lap charged with diamond paste or compound. The oil bottle allows the cutter to control the flow of lubricant, maintaining an even film on the lap surface and preventing the diamond abrasive from drying out or caking during polishing. Typical extender fluids include light mineral oil, synthetic oils, and proprietary blends formulated specifically for lapidary use. The oil bottle is among the standard accessories on the faceting bench.
Function in faceting practice
Diamond paste — a suspension of diamond particles in a carrier medium, charged onto a faceting lap as the abrasive — requires periodic addition of extender fluid to maintain its working consistency. As the cutter polishes, friction between the stone and the lap heats the abrasive, evaporates volatile components of the carrier, and gradually depletes the active diamond particles in contact with the work. Adding small amounts of extender oil refreshes the suspension, maintains lubrication, and extends the useful life of the charge.
The oil bottle delivers the extender in small, controlled drops or sprays. Too much oil floods the lap and washes out the diamond charge; too little allows the charge to dry out and lose effectiveness. Skilled cutters dispense one or two drops at a time, distributed across the working area of the lap, and refresh as needed during the polishing session.
Bottle types and dispensing
Several bottle styles are common. The classic plastic squeeze bottle with a fine nozzle allows the cutter to deliver controlled drops by gentle pressure. Glass dropper bottles with rubber bulbs offer more precise drop control but slower dispensing. Pump-action and pen-style applicators are less common but used by some cutters who prefer one-handed operation.
The bottle is typically labelled or colour-coded to identify the extender fluid, particularly important in shops that use multiple fluids for different applications (different oils for different lap materials, for example). Refilling is done from larger bulk containers between cutting sessions.
Position in the bench setup
The oil bottle sits within easy reach on the faceting bench, alongside diamond paste, polishing compounds, lap-cleaning solvents, and other consumables. A typical faceter's bench has multiple bottles for different fluids and lap charges. Organisation and labelling matter both for efficiency and to prevent cross-contamination between different abrasive grades or polishing media.