Why Denim Rubs Off: The Nature of Indigo
Most fabrics are dyed right through the fibre. Indigo denim is different. In traditional rope dyeing the warp yarns are dipped repeatedly, and each dip adds a thin layer of dye that clings to the outside of the yarn while the core stays white. That surface layer is what gives denim its character: it fades over time, shows wear lines and creates contrast. It is also why indigo can transfer onto other materials when rubbed, particularly if the fabric is damp.
So colour fastness in denim is not a question of eliminating transfer, which would change the product. It is a question of keeping transfer within a level the customer, the retailer and the care label can live with. The yarn and dye method matter, and our guide to indigo dyeing and black denim explains how rope, slasher and sulphur routes differ.
Crocking, Bleeding and Fading: Three Different Problems
The three are often mixed up in customer complaints, but the fixes differ. Crocking is mostly a finishing and wash-down issue, bleeding is mostly a rinsing and fixation issue and fading is a dye and fabric choice. Treat them separately in the spec.
The Tests: What They Measure
Colour fastness is checked in a laboratory using standard methods. For rubbing, the usual approach is a crockmeter that rubs a white test cloth against the denim a set number of times, once dry and once wet. For washing, a swatch is laundered with a piece of undyed multi-fibre fabric, and the staining on that fabric is judged. Examples of recognised methods include the ISO 105 series and the AATCC series, and your lab will tell you which fit your market. Confirm the method on the report rather than assuming.
Results are graded against a grey scale from 1 to 5, where 5 means no visible colour change or transfer and 1 means severe. Half grades are used. The grey scale is a visual judgement under standard lighting, which is why you should always test at an accredited laboratory.
Choose the tests that match how the product will be used. A pair of dark skinny jeans worn with white tops needs wet rubbing control. A brand selling to the sportswear-adjacent customer may add perspiration testing. A black or heavily overdyed style may need extra attention to washing staining. The garment testing guide shows how to commission a test programme.
Pass Levels Buyers Commonly Discuss
There is no universal pass mark. Retailers and brands set their own, and indigo denim is usually treated more leniently than other fabrics because of its nature. A common pattern is to expect a good dry rubbing result and accept a lower wet rubbing result for dark indigo, but the exact figure depends on your standard. For illustration, many specifications discuss a dry rubbing grade around 4 and a wet rubbing grade in the 2 to 3 range for dark indigo denim. Treat these as conversation starters and replace them with your own requirement.
| Item | What to specify | Notes |
|---|---|---|
| Dry rubbing | Minimum grey scale grade, on the washed garment | Usually the easier target; set it higher than wet |
| Wet rubbing | Minimum grade, with a separate target for dark shades | The usual cause of complaints; be realistic for dark indigo |
| Wash staining | Minimum staining grade on the adjacent fabric | Match the care label temperature |
| Perspiration or light | Include only where the product justifies it | Adds cost; relevant for pale or bright colours |
| Test state | Finished, washed garment, not greige fabric | Wash processing changes the result |
What Reduces Colour Transfer in Production
Factories and wash houses have several levers, and a buyer should know what to ask about. A thorough rinse and wash-down removes loose dye from the surface, which lowers crocking considerably. Soaping and neutralising steps help stabilise the colour. Fixing or after-treatment agents can improve wet fastness on some shades, although they may change the handle or the hue. Heavy stone or enzyme washes remove surface indigo, which reduces transfer but also changes the look, and our types of denim washes guide explains the trade-offs.
The darkest, richest shades are the highest risk. A deep rinse wash that keeps most of the indigo on the yarn will always crock more than a mid-blue stone wash. If the shade is non-negotiable, the answer is not a perfect test result but clear care instructions, honest product description and, where the market expects it, a first-wash warning.
Raw, Dark and Black Denim: Higher-Risk Shades
The less the denim is washed, the more dye remains on the surface, and the more it can transfer. Unwashed and rinse-only denim is the highest risk, which is part of its appeal to enthusiasts who want the fades to develop with wear. If you are selling that product, make sure the product page, hangtag and care label explain it. See raw denim vs washed denim for the positioning and briefing side.
Black denim brings different chemistry. Sulphur black dyes behave differently from indigo, and overdyed blacks can bleed or fade to grey or green in ways that surprise customers. Ask the mill and wash house for test data on the specific black, and check the fade direction after several washes, not just the first.
Care Labels and Customer Messaging
The care label is the part of your colour fastness plan the customer actually reads. Typical advice for dark denim includes washing inside out, washing with similar colours, using a low temperature and avoiding long soaks. The instruction should match the test: if you test at a particular temperature, the label should not recommend a harsher one. For the legal side of care and fibre labelling in the UK, see UK clothing labelling requirements and check current GOV.UK guidance.
Returns data is another source of control. If complaints cluster on one wash or one colour, you can raise the target for that style or add a hangtag note. Colour issues also show up at pre-shipment, which is why the jeans quality inspection checklist includes visual checks such as shade variation and visible staining.
A Worked Example: Briefing a Dark Wash
Imagine a brand developing a deep indigo, lightly washed slim jean for sale to customers who often wear it with white trainers and pale tops. The buyer's concern is wet transfer. A sensible briefing sequence looks like this. First, state the shade reference and tell the factory that transfer is a priority, not an afterthought. Second, ask the mill and wash house which dye route is used and whether any after-treatment is planned. Third, request a first wash sample, test it for dry and wet rubbing and washing staining at a laboratory and compare the result with the target.
If the wet rubbing result is below target, the options are practical rather than theoretical. The wash house can add rinses or a fixing step, the shade can be moved slightly lighter, the care label can ask for first washes to be done separately or the brand can accept the lower result and write clear customer messaging. Each option has a cost in time, price or appearance, and the buyer should choose consciously. The point is to make that decision at sampling, when a change costs a few days, and not at pre-shipment, when it can mean a delayed order.
For the full route from a first sample to a shipped order, the how to get jeans manufactured guide shows where wash and testing approvals sit, and the denim fabric weight guide is useful when you are choosing a base cloth for a dark colour, because fabric construction affects how a shade looks and behaves.
Common Mistakes
- Testing greige fabric only. The finished wash changes the result, so test the garment.
- One target for every shade. A mid-blue and a deep indigo need different wet rubbing targets.
- Copying a pass mark from another category. Standards for knitwear or shirts do not translate to indigo denim.
- Forgetting the care label. A good test result with a misleading label still creates complaints.
- Approving the first wash and ignoring the bulk lot. Dye lots vary; ask for lot-level results.
- Promising what the test does not support. Keep claims within the evidence.
A Colour Fastness Briefing Checklist
- Dry and wet rubbing targets on the grey scale
- Wash fastness (staining) target matched to the care label
- Test on the finished, washed garment, per colourway
- Named test method and laboratory on the report
- Wash-down and rinse steps for dark shades
- Lot-level results for repeat orders
- First-wash and care instructions drafted with the label
- Plan for returns and complaints feedback to the factory
The same checklist links to your cost and lead time planning. Extra rinses and testing add small amounts of time and money, and a very heavy wash step can affect the price; see the jeans costing sheet and denim production lead time guide for where they fit.
Denim Colour Fastness with Ruhrose
Ruhrose develops and produces denim in Bangladesh, with UK buyer support, so colour fastness is built into sampling instead of being discovered after shipment. We work from 500 pieces per style and colour on suitable programmes, and we can help you set rubbing and wash targets, arrange laboratory testing on the washed garment and draft care instructions that match the results. If you are developing a dark wash, a raw style or a black, start a product enquiry and tell us the shade, the target customer and your retailer's requirements.