Colour coding works because it is read from further away and through more dirt than any text. A picker walking an aisle can see a colour at ten metres and a part number at one. It fails in a predictable way: the scheme grows until nobody remembers what the colours mean, and then it is worse than no scheme, because people start guessing.
Keep it to four colours plus one
Four working colours plus one reserved for quarantine or non-conforming is about the limit of what a team will hold in their heads without a chart. If the scheme needs more, the answer is usually to split the fleet physically – colour for destination zones, and a label for the detail within each zone. Colour carries the coarse sort; the label carries the fine one.
Code one dimension only
A colour should mean exactly one thing. If red means both “line three” and “urgent”, it means neither after a month. Pick the dimension that produces the most sorting errors today and code that. In multi-site loops it is usually destination; within a single plant it is usually line or cell; where shift handover is the pain point, code the shift.
Put the legend where the work is
A legend on a wall in an office is not a legend. Put it at the point where boxes are sorted: on the rack upright, on the end of the returns trolley, on the door of the wash area. Four coloured squares and four words. If the sort happens in more than one place, put it in every one – the cost is a laminated sheet per location.
Colour in the material, not on it
Painted or printed colour wears off at the corners and handles within a year. Colour compounded into the PP sheet runs right through the material, so a scuffed box is still the same colour – and a cut edge is the same colour too, which is what makes it readable on a damaged box. Where a colour has to be applied later, use a welded-on coloured panel rather than a sticker.
What colour cannot do
Colour cannot carry batch, date or count, and it cannot be read by a scanner. It is a coarse sort and a mistake-reducer, not a traceability system. If the operation needs batch traceability, that is a barcode or a numbered plate, and the two should coexist: colour for where it goes, number for what it is. The zone-coding approach is described in colour coding protection zones.
Replacing a colour without breaking the scheme
Colour schemes survive for years and then something forces a change: a new destination, a product line closing, a supplier who cannot match a shade. Changing one colour mid-scheme is where most schemes die, because for a period nobody is certain what anything means. The transition has to be managed as a project rather than announced.
The workable method is to run the old and new colours concurrently with a temporary secondary marker – a label or a tape – on the boxes using the new meaning, and to withdraw the old colour entirely on a stated date rather than letting it drain. The secondary marker is what carries the meaning during the overlap. Announce the date, put it on the legend at every sort point, and on the date remove every remaining box of the old colour from service even if they are structurally fine. A partly-transitioned colour scheme is worse than no scheme, because it teaches people that the colours are unreliable.
What we can do
We supply PP corrugated turnover boxes in compounded colours that run through the sheet rather than sitting on it, with the same box available in several colours for a coding scheme. Tell us the dimension you want to code and we will keep the palette small enough to survive contact with real operators.