Lê Mai keeps two kinds of molds on the workbench. Wooden molds and silicon molds. From the same batch, two molds produce two different bars. This piece records the difference and the reason.
Two molds, one batch
The wooden mold is made of oak or pine planks, with an interior of 8cm wide by 30cm long by 8cm deep. It is lined with parchment paper each batch. One mold lasts ten years if kept dry.
The silicon mold is soft, cast as a single piece, of comparable dimensions. No paper liner needed. Bought once, it lasts two to three years before tearing.
When the same cold process soap mixture is poured into both molds, after 24 hours both blocks unmold at the same size, the same weight, the same pH. But they feel different in hand.
Wood breathes, silicon seals
Wood has a natural porous structure. During the 24 hours of saponification, water vapor and reaction heat escape through the mold walls gradually. The temperature inside the wooden mold rises moderately and stays even.
Silicon is fully sealed. Vapor and heat are trapped inside. The core temperature of a silicon mold can reach 70 to 80°C during gel phase, then cool quickly.
Result: a bar from the wooden mold has a more uniform crystalline structure. A bar from silicon shows a visible gel band through the centre, with outer edges sometimes not fully gelled.
The edge · marks and shine
The wooden mold leaves faint wood grain on the side faces of the bar. The edges sometimes show a white rim where the soap met the paper liner. The edges are not perfectly straight.
The silicon mold produces a smooth edge with a slight sheen, even as if cast in aluminium. No material trace, no grain. Four faces look the same.
Some find the silicon face more beautiful. Others find the wooden face more real. This is the fork. Lê Mai turns toward wood.
The feel in hand
Holding a bar from the wooden mold, the fingers meet several surfaces at once. One face smooth, one with faint grain, one with a white rim. The hand reads the difference.
Holding a bar from silicon, all four faces feel the same. Smooth. Even. Dry.
A small difference, nothing measurable, nothing easy to describe. But the hand knows. Set on a table, the wooden-mold bar sits more stably because its base is not perfectly flat. A slight instability becomes stability.
Why the uneven
A bar of soap is not a mass-produced product. It is a specific batch, from a specific day, from specific oils.
The wooden mold records this. The mold marks, the grain, the unevenness. All of it is the trace of a particular batch. Two bars from two different batches may carry different marks, even when the formula is identical.
The silicon mold erases this. Every silicon-mold bar looks like every other, regardless of batch, day, or oil.
Lê Mai chooses to keep the trace. A bar of soap need not be perfect. It needs to be itself, from that batch.
Wooden molds. Marks. Grain. Uneven.
A choice. Not an accident.