Pewter Polishing - Vibratory Tumbling

Many small-run, decorative pewter manufacturers either hand polish or have smaller equipment for polishing cast pewter parts. While we have detailed pewter polishing in a previous post using steel tumbling media, small vibe tumblers generally are not able to handle the weight of steel media.













Before (first) - Polished (second)

These lead-free pewter parts showed rough and dull surface finishes. While the objective was not to completely remove the flashing and produce a mirror-like surface finish, these parts did need to be cleaned and polished.

A two step process was used in a small (4 gallon capacity) vibratory bowl. The first step used a general purpose Ceramic Media and a mild acid compound to remove oxidation on the surface and soften/remove the flashing. This resulted in a smooth, matte finish. Instead of using steel tumbling media in the second, polishing step, a Precision Ceramic polishing media was able to bring up a nice shine on the parts in a relatively short cycle time of 2 hours. A neutral pH compound was used to keep the parts clean and bright.

Polishing Pewter

Molded pewter, rough surface finish

Pewter parts can be cast into a large variety of shapes. The casting process often results in a rough surface finish along with burrs and flashing on the edges. Surface finishing is often done by hand to produce a smooth finish and especially a high polish on the parts.

2-step polishing process

Mass finishing can be used to achieve all of the required deburring and edge rounding and often can result in a bright, smooth polished surface finish.

The part on the right was vibratory tumbled with a Ceramic Media to remove the molding marks and soften the edges. The second step to polish to surface (part on left) involved barrel tumbling with Stainless Steel Media with an appropriate burnishing compound. You can even see the camera reflection. Additional polishing can be done by hand if necessary.

The mass finishing process will significantly reduce the amount of hand work required. Vibratory and/or barrel tumbling will also allow for difficult-to-handle small parts to be deburred and polished successfully.

Finishing Pewter

Pewter is a soft, malleable metal consisting primarily of tin. Decorative plates, jewelry, figurines and even keys (see picture below) can be made with pewter. Since pewter is so soft, it is difficult to maintain a polished finish on the surface. It is common to treat the pewter design with a black coating that is then polished away from the high spots to produce an exaggerated 3-dimensional effect.

Key Art Co.

The black oxide coated parts are vibratory tumbled with Precision Ceramic Spheres and a mild acid cleaner such as Kramco 1030 to 'clean' the high spots. The spheres provide an excellent bright and clean finish without removing the oxide from the interior relief areas of the part. Cycle times can be as short as 10-15 minutes depending on the desired results.

If a matte finish is more desirable, a cutting/abrasive version of the Precision Ceramic Spheres can be used. To remove more of the oxide, a triangle media is ideal.