Colourfastness to Crocking and Perspiration

Colourfastness to Crocking and Perspiration

Colourfastness to crocking measures how much colour rubs off onto another fabric, and colourfastness to perspiration measures how much colour bleeds when it meets acidic or alkaline sweat. Both use a grey scale to score transfer, and both fail far more often on deeply saturated shades than on light ones. Agree the grade you need before bulk starts, then test the actual dye lot rather than the lab swatch.

These two tests get confused with wash fastness, which is a different question. Wash fastness looks at colour loss after laundering. Crocking and perspiration look at transfer onto a contacting surface, which is what a customer notices when a dark garment marks a white shirt collar or a light bag strap. A fabric can pass wash testing and still fail colourfastness to crocking.

What the Crocking Test Measures

The crocking test rubs a dry white cloth and a wet white cloth against the dyed sample under controlled pressure, then scores the staining on the white cloth. The wet rub is the harsher of the two, which is why a fabric often passes dry crocking and fails wet crocking. Surface dye that has not bonded fully into the fibre is what transfers. Dark saturated shades carry more unbonded pigment, so colourfastness to crocking is tightest for black, navy, and deep red programs.

Finishing is the lever. A rinse step that clears loose surface dye lifts the crocking grade without changing the shade. Skipping it to save water or time shows up later as transfer complaints. If your supplier cannot say what rinse sequence the lot received, treat the colourfastness claim as unverified and test it yourself. This kind of check belongs in the routine described in how to test print on demand products cheaply.

What the Perspiration Test Adds

The perspiration test soaks the sample with a solution that mimics acidic sweat, and separately with an alkaline version, then presses it against a white cloth and scores the transfer. Some dyes respond very differently to the two solutions, which is why a fabric can pass one and fail the other. Colourfastness to perspiration matters most on necklines, underarms, and waistbands, where cloth sits against skin for hours.

Metals complicate the picture. Copper and iron traces left on fabric can accelerate fading and transfer under perspiration, so a supplier who handles metal trim and dyed goods in the same area without separation can introduce a failure that never shows in a clean lab swatch. Ask about that separation if the colourfastness problem appears only on production lots and never on samples.

Why Dark Shades Fail More Often

Pigment load is the driver. Reaching a deep shade takes more dye or pigment in the bath, and the fibre can only bond so much. The surplus sits near the surface, which is exactly where the rubbing cloth and the perspiration pad reach it. This is also why dye choice matters, since some classes bond more completely than others at the same apparent shade depth. Testing colourfastness across shades rather than on one sample tells you whether the problem is the dye class or the application.

Setting Acceptance Criteria Before Bulk

Write the required grade into the specification so there is no argument later. Naming a grade for both dry and wet crocking, plus both perspiration solutions, closes the loophole of a supplier reporting only the pass they achieved. Then attach the test to the lot rather than the style, and re-test when a new dye lot appears. The reference table in colour fastness grades and what they mean is a practical way to translate a grade into a customer-visible outcome.

Combine the two tests with a durability check so you are not testing in isolation. A garment that survives rubbing but loses its print after ten washes still generates returns. Running colourfastness to crocking and perspiration alongside print durability testing before launch gives you one combined verdict per lot instead of four disconnected reports. Where the print is applied over a dyed fabric, also DTG pretreatment and why it affects wash fastness is worth reading, because pretreatment chemistry can shift how the dyed ground behaves under moisture.

Track results per lot in a simple log with the dye lot code, the base fabric, the test date, and the grade. Add the rinse sequence if the supplier discloses it, because that single field explains most of the lot-to-lot variation you will see over a season. After three or four lots you will see which suppliers hold colourfastness to crocking and perspiration reliably and which ones vary. That pattern is far more useful than a single certificate, because variations are what produce the returns that a certificate never predicted. Fabrics that carry documented colourfastness records are worth starting from, and the custom product catalogue lists options with those specifications already on file.

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