BioChromes¶

Week 4 assignment for Fabricademy. This page documents a small experiment with traditional Chinese medicinal plants used as bio-dyes — the same plants that go into herbal decoctions, here repurposed to colour cotton. This page is the recipe and the notebook, written before the shopping, to be filled in once the dyed swatches come back from the drying rack.

1. Objective¶

What I'm doing this week. A small dye palette built from Chinese medicinal herbs — same plants that go into the decoctions, here used to colour cotton. The exact herbs and shades will be settled after a visit to the local herbalist; this page is the recipe and the notebook, written before the shopping.

2. References, research & inspiration¶

2.1 Inspiration — how two herbal-dye references fed into this experiment¶

Two reference sources from 小红书 shaped the starting palette and the methodology.

• 服设作品集｜中药染小教程｜过程记录 — LOAE Fashion Workshop. Seven herbs tested as fabric dye: 鸡血藤 (Spatholobus suberectus), 墨旱莲 (Eclipta prostrata), 花生衣 (peanut skin), 苏木 (sappanwood), 黑豆衣 (black soybean skin), 母丁香 (clove fruit), 枇杷叶 (loquat leaf). The post documents the full bench process and ends with a finished garment cut from one of the dyes. Source: Xiaohongshu.
• 18种药材植物染色色谱参考 — 木子的养生小院. A reference swatch book of 18 medicinal herbs used as dyes (incl. 板蓝根 (indigo root), 紫草 (gromwell), 茜草 (madder), 苏木 (sappanwood), 槐米 (pagoda bud), 栀子 (gardenia), 姜黄 (turmeric), 桑葚 (mulberry), 五倍子 (gallnut)…). The reference shows each herb in different mordants — useful for predicting tonal range before committing. Source: Xiaohongshu.

2.2 Other reference reading¶

The herbal-dye tradition is well documented in Chinese sources. The piece that most informed my workflow is 图鉴 | "好色"本草染 from Nanjing University of Chinese Medicine — a modern herbal-dye atlas with photos of each plant, its decoction, and the resulting cloth. It is also the source for the herbs I shortlisted. Source: zwy.njucm.edu.cn.

The methodological backbone — scouring, mordanting, dyeing, pH shift, post-treatment — comes from standard natural-dye craft references (see Recipe files & References at the bottom).

2.3 Process rules I am setting for myself¶

• One swatch per herb, three swatches per herb (no mordant / alum / iron) — so each plant produces a small tonal strip rather than a single colour.
• White cotton as the substrate. Easier to source, easier to compare. Skipped protein fibres for now.
• Mordants kept simple: alum (bright/clear shift) and 皂矾 / ferrous sulphate (duller, greyer shift). Both are pharmacy staples.
• The palette will be presented in hue order — not in medicinal-action order.

3. Tools¶

3.1 Materials I will buy¶

Herbs (open list — final selection depends on what's at the herbalist):

The starting palette below is the shopping list — not a final experimental design. Each row links the herb to the colour family it tends to land in, so I can swap out anything unavailable and keep the hue coverage intact.

I will buy what is in stock — at least one from each hue family if possible. If a herb is missing, the table above is the backup palette.

Other supplies:

• Alum (明矾) — bright mordant. Sold at any Chinese pharmacy.
• Ferrous sulphate (皂矾 / 绿矾) — greying/darkening mordant. Sold at the same pharmacy.
• Plain white cotton fabric — small squares, roughly 8 cm × 8 cm, one per herb × 3 mordant conditions = ~30 swatches.
• Baking soda (小苏打) and white vinegar — for pH shift tests.
• Glass jars or small pots, one per dye (cannot reuse for food).
• A notebook — to log the empirical process: herb weight, water volume, simmer time, mordant weight, time in bath, pH.

3.2 Hardware¶

• A small stovetop or electric kettle
• A kitchen scale (1 g resolution)
• A fine mesh strainer or cheesecloth
• Stainless-steel tongs / a wooden spoon
• A drying rack (a clothesline works fine)
• A camera / phone with neutral-light photos (window is best)

4. Process and workflow¶

4.1 Step 1 — Pre-wash the cotton¶

Submerge the squares in a pot of plain water with a few drops of neutral soap. Simmer 30 min, rinse, dry. This strips factory sizing so the mordant can attach.

4.2 Step 2 — Mordant bath (75 min)¶

For each dye pot I am preparing three swatches: one without mordant, one with alum, one with ferrous sulphate.

• Alum: ~10–15 % of the dry fabric weight. Dissolve in warm water. Add pre-wet cotton, simmer 60 min, leave in the bath until cool, do not rinse.
• Ferrous sulphate: same ratio, same process — but keep in a separate pot (iron contaminates everything it touches).
• "No mordant" swatch: skip this step entirely.

4.3 Step 3 — Dye extraction¶

• Weigh ~30–50 g of the herb.
• Add ~500 ml water, bring to a gentle simmer, hold 30–45 min.
• Strain through cheesecloth. The liquid is the dye bath.
• For 紫草 (gromwell) specifically, use 30 % ethanol / 70 % water instead of plain water — the naphthoquinone pigment is barely water-soluble.

4.4 Step 4 — Dye the swatches¶

• Add the three pre-mordanted (or unmordanted) swatches to the dye bath.
• Simmer gently 45 min. Stir occasionally so the colour lays evenly.
• Turn off heat, leave the swatches in the cooling bath for another hour. Letting them sit while cooling pulls more pigment out.
• Pull out, do not rinse yet.

4.5 Step 5 — pH shift test (one herb, at the end)¶

To see how pH moves a hue, take one dyed swatch, cut it in thirds, and soak the three pieces in: (a) plain water, (b) a teaspoon of vinegar, © a small pinch of baking soda. Five minutes each, rinse, dry. Record the result.

4.6 Step 6 — Dry and photograph¶

• Air-dry the swatches flat, away from direct sun (UV shifts the colours while drying).
• Photograph each swatch on a neutral grey background, in daylight. Keep lighting consistent across the whole series — that is what makes the palette readable.

5. Deep dive — 苏木 (sappanwood) SOP¶

A companion protocol to the generic workflow above. Same mordants (五倍子单宁 / 明矾 / 皂矾), same pH-shifter trio, same 15×15 cm cotton swatches — but sappanwood is a mordant dye, so the procedure reads differently. This is the second recipe I will run alongside the turmeric deep dive.

5.1 Why sappanwood behaves differently¶

This is why the sappanwood SOP must include the ferrous-sulphate path — iron is the soul variable here, and it has no equivalent in the turmeric experiment.

5.2 Materials & concentrations (cotton basis)¶

Ferrous sulphate is dosed lower than alum on purpose — ferrous iron saturates cotton quickly; excess stiffens and greys the fabric instead of turning it purple.

5.3 Experimental design: 7 experimental + 1 backup¶

Cutting: S1–S6 at 15×15 cm, S7 as a 30×8 cm strip, one spare. Label the corners, scour first, then into the baths.

5.4 Procedure (order & timing)¶

1. Scour (all 7): hot neutral soap bath 30 min → rinse → set aside.
2. Tannin bath (S2–S7): gallnut 10 g/L, 60–70 °C, 45 min or overnight. S1 skips.
3. Mordant bath (two paths):
4. Alum path — 15 g/L, 50 °C, 30 min → S3, S5, S6, S7.
5. Ferrous path — 5 g/L, room temperature, 15 min → S4. Never heat the ferrous bath past 50 °C — ferrous oxidises to ferric and the colour turns muddy.
6. Sappanwood dye bath (all 7): 50 g/L + 1 L water, simmer 30 min → strain (discard the chips). Cool the liquor to 50–60 °C, then dye 30–60 min: 30 min = standard depth; 60 min = deep brick red; overnight (8 h) = near black-purple. The bath is single-use — sappanwood oxidises fast and the colour drops within hours, so re-boil a fresh pot each time.
7. Post-dip (S5, S6, S7): citric acid 8 g/500 ml, 5 min → orange-red. Soda ash 3 g/500 ml, 1–2 min then rinse → deep purple-red; past 3 minutes it browns. S7 strip folded in three segments: acid → clear water → alkali.
8. Rinse & dry: no direct sun — sappanwood darkens to a dull purple. Rinse until the water runs clear, dry in shade, store away from light.

5.5 Three pitfalls (read against turmeric)¶

1. Iron and sappanwood in the same pot = black sludge. The ferrous path must be mordant-first, dye-second. Iron straight into the dye liquor gives lumpy purple precipitate, grey stiff fabric — nearly a write-off.
2. One bath only. The moment the liquor meets air, oxidation starts and the colour falls off a cliff. Finish the pot, dump it, re-boil for the next round.
3. Ferrous: fast, small, cold. 5 g/L, room temperature, 15 minutes. More, longer, or hotter and the colour turns dirty.

5.6 Comparison items to record after dyeing¶

• Actual hue + estimated RGB for each swatch S1–S7
• Tannin vs no tannin → depth of shade (S1 vs S2)
• Ferrous vs alum → red vs purple (S3 vs S4)
• Acid vs alkali post-dip → orange-red vs deep purple-red (S5 vs S6)
• 30 min vs 60 min dyeing time (optional, if a second bath is split off)

6. Results¶

6.1 The palette¶

to be filled in after dyeing.

Aiming for a single image showing all swatches in a clean grid — one row per herb, three columns (no mordant / alum / iron), captioned with the herb and the empirical hue.

6.2 Documenting experiments in a table¶

A table comparing each herb's effect across the three mordant conditions — this is the comparison layer the rubric mentions.

6.3 pH shift notes¶

For at least one herb, document how acid / base shifts the final colour.

7. Weekly reflection & critical thinking¶

• What did I learn? What surprised me about the herbs' behaviour vs the reference charts?
• Which dye was the hardest to control, and why?
• How does this connect to my practice — what would I do with this palette next?
• Ethical / environmental reflection: where do these herbs come from, what does using them as dye mean for their medicinal supply, is this practice sustainable?
• Did any colour land somewhere unexpected, far from what the reference charts predicted?

8. Recipe files & References¶