SHAPE THE NEEDLE
QUENCHING AND TEMPERING - Steps 9 and 10
Quenching : needles are hardened by thermal shock by passing suddenly from 835°C oven to a cold oil bath. Tempering : The needles are then plunged into a second oil oven at 180°C to maintain flexibility. After these two processes, the needles will be both hard and flexible, ready to be used.
DRYING AND WINNOWING - Steps 11 and 12
To continue the production process, the needles have to be completely clean and dry. The needles are placed in a rotating barrel filled with sawdust. The sawdust absorbs the liquids, drying the needles. Then to clean them, they are placed in a machine precisely calibrated to shake off the sawdust and let the needles fall out, this is called : "vannage".
ARRANGING ON A TRAY- Step 13
The needles are placed on a large, ridged wooden tray. By rapid shakink in a particular way, they fall on top of one another, between the ridges, at one end of the tray. The tray was already being used in the 19th century.
POLISHING - Step 14
This step gives BOHIN's needles their famous smoothness ! Needles are wrapped in a treated sheet of canvas, covered with oil and abrasive. This oilcloth is sewn up into a roll which is then placed on a polishing machine. Under the pressure of the cylinders, moving alternately, the back and forth movement polishes the needles.
DRYING AND WINNOWING - Steps 15 and 16
To continue the production process, the needles have to be completely clean and dry. The needles are placed in a rotating barrel filled with sawdust. The sawdust absorbs the liquids, drying the needles. Then to clean them, they are placed in a machine precisely calibrated to shake off the sawdust and let the needles fall out, this is called : "vannage".
NICKEL PLATING - Step 17
Le nickelage est un traitement électrolytique qui protège l’aiguille de l’oxydation (autrement dit, la corrosion) tout en la rendant brillante et glissante. Une fois nickelées, les aiguilles sont nettoyées en passant dans de l’eau savonneuse, de l’eau chaude, de l’eau froide, séchées dans un séchoir.
DRYING AND WINNOWING - Steps 18 and 19
After the previous operations, the needles have to be completely clean and dry. The needles are placed in a rotating barrel filled with sawdust. The sawdust absorbs the liquids, drying the needles. Then to clean them, they are placed in a machine precisely calibrated to shake off the sawdust and let the needles fall out, this is called : "vannage".