Liver of sulphur is a standard patination chemical for silver and brass. Most jewellers apply it by dipping the whole piece into a warm solution, which oxidises every surface evenly. At Spruce Crest Path, it is applied with a fine brush, one surface at a time. The difference in result is significant, and the reason for doing it the slower way is specific to how the pieces here are designed.

What liver of sulphur does

Liver of sulphur is a potassium polysulphide compound. When it contacts silver or brass, it forms a thin layer of metal sulphide on the surface. That layer is dark, ranging from pale gold through brown to near-black depending on concentration, temperature, and contact time. The reaction is fast on warm metal and slower on cold. It is reversible with polishing compound, which is why oxidised pieces can be refreshed if the patina wears unevenly over time.

Bath oxidising versus brush oxidising

Bath oxidising means submerging the whole piece in a dilute solution. Every surface darkens at roughly the same rate. The result is an even, all-over patina. For pieces with a single surface, that is fine. For pieces with raised planes and recessed angles, it means the raised surfaces go as dark as the recessed ones, which flattens the contrast. Brush oxidising means applying the solution only to the surfaces you want to darken. The raised planes are masked by not touching them. The recessed angles go dark. The contrast between bright and dark is the point of the design.

The brush technique in practice

The brush is a size 0 watercolour brush, which gives enough control to stay within a 1 mm channel. The liver of sulphur solution is mixed at roughly half the standard concentration, because a weaker solution gives more working time before the reaction is complete. The piece is held at room temperature rather than warmed, again to slow the reaction. The solution is applied in two or three passes, checking the colour between each pass. When the recessed surface reaches the target tone, the piece is rinsed immediately in cold water to stop the reaction.

How heat in the studio affects the process

In summer, the studio in Nagano gets warm by mid-morning. Warm ambient temperature accelerates the liver of sulphur reaction even at reduced concentration. The practical result is that the patina goes darker faster and is harder to control. The July 2026 batch was made in early morning sessions specifically to avoid this. Working before 9 in the morning, when the room is still cool, gives about twice as much working time per application as working at noon. This is a small thing but it matters for consistency across a run of six pieces.

Maintaining the patina over time

The oxidised finish on a piece from this studio will wear on the raised surfaces over time, which is expected and not a problem. The recessed angles, which are protected from contact, hold their dark tone much longer. If the overall contrast fades more than you want, the finish can be refreshed. Send the piece back to the studio with a note and it will be re-oxidised and returned. The cost is included in the standard repair fee.

The brush oxidising step is one of the slower parts of making a piece here. It is also the step that most directly produces the look that makes the work recognisable. Notes from the bench has more on the process if you want to read further.