Some Notes on Tumbling
Tumbling is a method which can in some situations greatly reduce the amount of hand polishing needed to achieve good polishing. Tumble cutting with abrasive chips will remove some roughness from cast surfaces. Tumble polishing with steel shot will burnish (without removing metal) interior and exterior surfaces to a shine. It is especially useful in burnishing interior openings which are difficult to reach with polishing machine brushes and buffs.
The are several problems associated with tumbling:
- Tumbling does burnish away some amount of detail, such as sharp corners.
- While we do furnish instructions for general procedure, these instructions are only guides. The user must spend a great deal of time in experimentation to determine specific procedures for his jewelry. Sometimes he achieves good results in a relatively short time. For most users this learning process takes many, many month of experimentation.. Despite the fact that we have sold hundreds of tumbler to the jewelry trade, we are still unable to furnish the specific answers need by each different client. We, therefore, furnish tumblers with our standard instructions but with no guarantee that the client will be satisfied with the results.
Polishing with Shor Tumblers
Fill the outer compartment of the tumbler with fresh water up to the level of the rotating shaft. Fill each inner compartment of the PT3 or PT4 tumbler approximately to ½ full of steel (approximately 20 lbs.) IF the quantity of media exceeds 50% of the space, there will be less of a "fall" or "slide", thus causing slower and gentler action of on the jewelry; Add 2 oz of burnishing soap to each compartment. Put the jewelry in the compartment in the proportion of about 1/4 as much jewelry as steel shot. Best results will be obtain by separating yellow from white gold and by putting pieces of approximately the same size into the compartment. Tumbling time will vary from 1 hour to as much as 18 hours depending upon the size and shape of the shot, surface of the jewelry will be affected by the surface of the shot, proper maintenance of the shot is important. Always flush the steel shot clean after each tumbling operation, then submerge the steel shot in water with rust preventative so that it is not subject to corrosion by air. Change the water in the tumbling barrel each day.
Treatment of Blackened Shot
The blackened shot is placed in the tumbling barrel. The tank is filled with water to approximately the level of the rotating shaft. Add three tablespoons of oxalic acid added to the water and tumble in this solution for approximately two to three hours.
The solution is drained from the tank and the procedure is repeated with fresh water and oxalic acid as above. Tumble for approximately one hour.