Process at the Material — textile testing

Role: Sole author
Lab: HAW Hamburg
Course: Textile dyeing · WS 24/25
Standards: ISO · DIN · UN/ECE
Protocols: 5, written up

Textile testing at HAW Hamburg — five protocols, each its own question. What follows is their order, with what came out of each.

Heated stirring plate with two metal beakers holding the dye baths — The bench · bath on the hotplate

Drying oven set to 60 °C — Drying oven · 60 °C

Reactive surface dyeing Cotton

The dye binds covalently to the hydroxyl groups of the cellulose. Sodium carbonate colours nothing — it lifts the bath to pH 11–12 and activates the anchor. Intensive soaping removes what only clung on.

Brilliant and wash-fast — but the yield fluctuates and chlorine attacks it.

Dyeing curve — 20 °C to 60 °C, sodium carbonate in two halves, then rinse — The curve, as run

Acid test dyeing Five fibres, one bath

Acid dyes are negatively charged and need a positive fibre surface, so the bath runs at pH 2–6.5. Predicted before, confirmed after: wool takes it, polyamide takes it, acrylic partly, cotton and polyester barely.

The fibre decides before the dye does — and you can say so in advance.

Five fibre samples after the acid bath, before washing — Unwashed · WO PA SE CO PES

The same five samples after washing — Washed · the same five

Acid dyeing curve — up to 90–100 °C, then rinse — The curve · 90–100 °C

Reflectance spectrum — the undyed cotton reference reflects 61 to 80 percent evenly; the dyed sample drops to a minimum of 9 percent at 530 nanometres, then rises steeply from 575 nanometres — **03 · Reflectance** — the reference reflects evenly; the dyed sample drops where the dye absorbs. A colour you can reorder, argued from a curve instead of a light box.

Fastness analyses Wash · rub · perspiration

Cotton with Remazol Brilliant Orange 3R and Brilliant Red BB, through the full family: wash to DIN EN ISO 105-C10 at 60 °C against a multifibre fabric, dry and wet rub, artificial perspiration acid and alkaline.

Dry rub: 4/5 4.9
Wet rub: 4 4.8
Wash · bleed: 4 4.6
Staining: 4/5–5 4.7–5.0

Graded twice — by eye against the grey scale and instrumentally. Weak spots: wet rub and alkaline perspiration.

Rub-fastness cloths, dry against wet — Rub cloths

Dyed sample judged against the grey scale — Grey scale

Multifibre adjacent fabric, American Style 10A — The strip, unused

Multifibre accompanying fabric after the 60 °C wash — The strip, after washing

Surface & thermal trials Presentation to follow

A second series on surface behaviour — specimens cut and marked in warp direction, mounted, and run against a controlled temperature. Written up separately.

Documentation being added.

Dark fabric coupons cut and marked with the warp direction — Cut and marked · warp direction

Two temperature controllers reading 123 and 124 °C, labelled upper and lower — Controlled at 123/124 °C

Coupons bonded to a light backing fabric — Mounted specimens

Mounted specimens laid out for assessment — Laid out for assessment

The Textile Lab

Run and documented at HAW Hamburg, beyond the thesis. Each to its own standard.

T—01Tensile & seam strengthUN/ECE R16 · ISO 13934-1

T—02Abrasion resistanceMartindale · DIN 53863

T—03PillingMartindale pilling

T—04Friction & rubSurface / crock testing

T—05ColourfastnessWash · perspiration · light (ISO 105)

T—06Dyeing & finishingNatural & reactive · reproducible

T—07SpectrophotometryReflectance · colour matching

T—08FlammabilityISO 3795 · DIN 75200

T—06 in full · one series end to end

A natural bath on three fibres — and a light test that contradicted itself.

Four ripe pomegranates, skins dried overnight at 60 °C, then simmered ninety minutes at 90 °C. One natural bath, three fibres — wool, cotton, viscose — each run three ways: raw, mordanted with alum, and with alum plus iron sulphate.

Wool took the colour in every variant. Cotton and viscose stayed almost white — tannins bond to the amino groups of protein fibres and barely engage cellulose, so the fibre decides the result before the dye does. Alum pulled the wool to a clear gold; iron sulphate pushed the same bath to olive. Washed at 40 °C to DIN EN ISO 105-C10, the alum-mordanted wool came back at grade 5 on the grey scale. The unmordanted sample at 4. One mordant, one full grade.

Then the light test contradicted itself. Sixteen hours under DIN EN ISO 105-B02, cycle A1 — and the exposed side of the iron-mordanted wool came out darker than the shaded side. The opposite of fading. Light had kept oxidising the iron–tannin complexes long after the bath was drained. Not a spoiled sample: a reaction that does not stop when the process does. Antioxidants in the liquor would slow it; chitosan on the cellulose would give the tannins something to hold.

This series

Method: ISO 105-C10 · 105-B02
Fibres: WO · CO · CV
Mordants: None · alum · alum + iron
Result: Grade 5 vs 4

Wool dyed with pomegranate, unmordanted — warm medium yellow — **Fig. 13** · Wool, no mordant

Wool dyed with pomegranate after an alum mordant — clear gold — **Fig. 14** · Wool, alum

Wool dyed with pomegranate after alum and iron sulphate — olive brown — **Fig. 15** · Wool, alum + iron

Cotton dyed with pomegranate after an alum mordant — barely coloured — **Fig. 16** · Cotton, alum

Dried pomegranate skins, the dye source — **Fig. 17** · The dye source