Vat 4 — day six, morning check

Surface bloom is coppery and holds together when I nudge it. The liquor underneath has gone a flat amber, which is what we want before any cloth goes in.

Strip reads 10.4. A shade high, so I fed it a half cup of bran and left the lid cracked for an hour.

Dipped a test tab of linen for ninety seconds. Came out yellow-green and oxidised to a soft mid-blue in about four minutes.

Second dip took it two shades deeper. The grain of the weave is still legible and there is no bronzing at the selvedge.

Third dip flattened the colour, so I am stopping at two for this batch.

Next check at dusk. If the bloom thins, warm the vat and rest it overnight.

Six days of notes from a fermented indigo vat

Vat 4 — day six, a second pass

Started the check an hour earlier. Bloom had spread to the rim overnight and sat thicker than yesterday, almost coppery at the edges.

Strip reads 10.1 after the bran feed. Left the lid off for twenty minutes to let it settle again.

Linen tab, ninety seconds, one dip. Oxidised slower than yesterday — closer to six minutes before the blue held.

A second tab went in wet and came out patchy along one edge, so the liquor is not fully still yet.

Rested the vat, skimmed the flower into a jar, and left it until dusk.

Next: test a wool tab against the same dip count.

Six days of notes from a fermented indigo vat