Barcode and Carton Marking for Knit Bags: The Mark Panel, the SSCC-18 Label and an 18-Point Checklist That Clears the Dock

What a Carton Mark Has to Answer at the Dock

A carton mark has to answer five questions without anyone opening the carton: who it is for, what is inside, how many, which carton of the set this one is, and how heavy it is. A mark that answers four of the five will be opened at the distribution centre, and a mark that answers three will be held.

That is the whole reason the mark exists, and it is worth stating plainly because the mark is usually designed by whoever last touched the artwork rather than by whoever receives the goods. A distribution centre working a 40ft high-cube container of knitted bags is handling roughly 670 cartons. It scans, it does not read. Every line on the panel that exists for a human who will not read it is space taken from the lines that get scanned.

Knit programmes add one complication. A knitted bag compresses, so a carton of knit bags is usually volume-limited rather than weight-limited: a 60 x 40 x 40 cm carton of knit totes in polybags reaches its 12 kg limit at about 200 pcs while still having air in it. That means a container can carry a great many cartons for relatively few kilograms, and the carton count on the mark becomes the number the receiver reconciles against, not the weight.

The Mark Panel: Eight Lines and Why Each Is There

Eight lines is the practical maximum for a knit bag shipping mark: consignee, purchase order, style and colourway, quantity, carton number of total, net and gross weight, carton dimensions, and country of origin.

Barcode Layer: EAN-13 on the Bag, SSCC-18 on the Carton

Two barcode layers are used and they do different jobs: an EAN-13 on the retail article identifies the style and colourway at the checkout, and an SSCC-18 on the carton identifies that individual carton through the supply chain.

The SSCC-18 is an 18-digit Serial Shipping Container Code carried under GS1 application identifier 00 in a GS1-128 symbol. It is serial: no two cartons in the shipment carry the same number, and the number is never reused. That seriality is what lets a receiver scan one carton and know exactly which carton it is, which cartons preceded it and which are missing. It is also what makes the carton sequence line on the mark panel redundant for a receiver who scans, which is why the sequence line is the first one to be dropped when space runs short.

Retail symbol

EAN-13, 13 digits, on the hangtag or on the polybag sticker

Logistic symbol

SSCC-18 under GS1 application identifier 00, in a GS1-128 symbol

X-dimension

0.495 mm minimum, 1.016 mm maximum for a GS1-128 logistic symbol

Bar height

32 mm maximum for a GS1-128 carton label, 25 mm typical

Quiet zone

10 times the X-dimension on each side of the symbol

Print resolution

300 dpi minimum for thermal transfer; 203 dpi is not enough at 0.495 mm

Scan grade

ISO/IEC 15416 grade C or better, verified with a calibrated verifier

Label stock

Thermal transfer on a coated face stock at about 80 gsm

Print Quality: What a Scan Grade Actually Measures

A barcode scan grade under ISO/IEC 15416 is not a judgement about how the label looks: it is a set of measured parameters, and a label that looks perfect can still fail on modulation or on edge determination.

The grade is the lowest of several parameter grades, so one weak parameter sets the grade for the whole symbol. In practice the two that fail on knit bag cartons are edge determination, caused by printing a logistic symbol on a desktop 203 dpi thermal printer, and defects, caused by a printhead with a blocked element drawing a void through the bars. Both cost little to fix at the packing line and a great deal to fix at the distribution centre, where the fallback is hand-keying 18 digits into a handheld terminal for every carton in the container.

The verification discipline that works is simple and takes five minutes per shipment: verify the first label of each print run with a calibrated verifier, record the grade, and re-verify if the roll changes. A programme that verifies once per shipment catches printhead failure in week one; one that never verifies discovers it when 670 cartons arrive unscannable.

The Carton Marking Checklist

Eighteen checks cover a knit bag carton mark, and the ten that are missed most often are the ones about sequence, seriality and consistency between documents rather than about spelling.

• Consignee and distribution centre code match the purchase order — a wrong DC code sends the carton to the wrong building.
• Purchase order number appears on the mark and on the commercial invoice with identical characters.
• Style code and colourway code appear, and the colourway code matches the pack plan exactly.
• Quantity per carton is the nominal pack quantity, not the last carton's partial quantity.
• Carton sequence runs 1 of N through N of N with no gaps and no duplicates.
• Gross weight is stated to one decimal and matches the scale used at packing.
• Net weight is stated separately; customs entry in several markets needs both figures.
• Carton dimensions in cm match the carton actually used, not the spec sheet.
• Country of origin is printed on the carton, not applied as a sticker at the last minute.
• SSCC-18 is unique per carton and has not been used on a previous shipment.
• SSCC-18 is printed with application identifier 00 in parentheses in the human-readable line.
• X-dimension sits between 0.495 mm and 1.016 mm for the logistic symbol.
• Quiet zone of ten times the X-dimension is clear on both sides of the symbol.
• Label is a thermal transfer print at 300 dpi or better, on coated face stock.
• First label of the run is verified to ISO/IEC 15416 grade C or better and the grade is recorded.
• Mark is placed on two adjacent sides so one is visible however the pallet is turned.
• Mark is offset at least 50 mm from the base, clear of the pallet band and the stretch wrap.
• Carton count on the mark reconciles with the packing list and with the AQL 2.5 inspection report.

Numbering, Weight and the Count That Reconciles

The number that reconciles a knit bag shipment is the carton count, not the piece count, because a knitted bag carton is volume-limited and the piece count is fixed by the pack plan while the carton count is not.

A 60 x 40 x 40 cm carton at a 12 kg limit holds about 200 knit totes in polybags. A 20,000-piece order is therefore nominally 100 cartons, and in practice 101 or 102 because the last carton is short and because a mixed-colourway order produces part cartons at each colourway change. The packing list has to show those part cartons as separate lines with their own SSCC, because a receiver reconciling 102 cartons against a packing list that says 100 will raise a query that holds the container.

Where the Label Goes on the Carton

The SSCC label goes on a side face of the carton, not on the top, offset at least 50 mm from the base and at least 50 mm from any vertical edge, and the printed mark goes on an adjacent face.

The reason for two adjacent faces is orientation. A pallet of cartons is wrapped and banded, and whichever face was facing out when the pallet was built may face inward after the pallet is turned in the container. Two faces guarantee that one readable mark is visible from any approach. The reason for the 50 mm offset from the base is the pallet band: a band sits about 25 mm to 40 mm up the carton, and a mark under the band is covered by it. The reason for avoiding the top face is stacking: a carton eight layers down on a pallet has its top face under another carton.

What Fails at Customs Entry and Why

Carton marking fails at customs entry for three reasons in practice: a piece count that does not reconcile, a country of origin marking that is not on the article, and an origin or fibre claim that has no document behind it.

The first is arithmetic and is prevented by the reconciliation discipline above. The second is a marking rule: several destination markets require origin marking on the article as well as on the carton, and on a knitted bag that means the woven label or the hangtag, not only the shipping mark. The third is documentation: a recycled-content claim on the bag needs a Textile Exchange GRS transaction certificate, and a claim that a shipment is of a particular origin needs the origin evidence to match the mark. A mark that claims something no document supports is the failure mode that costs weeks rather than days.

Fitting Marking Into the Sampling and Bulk Window

Carton marking artwork is approved inside the 7-working-day sampling window, because the mark carries the style and colourway codes that are only final once the sample is approved, and the SSCC range is allocated during the 30-day bulk window rather than before it.

The SSCC point is worth being precise about. A GS1 company prefix is allocated once to the brand or to the nominated shipper; the serial numbers within it are assigned at packing. A programme that assigns serials before packing ends up re-labelling cartons when the carton count changes, which is the most common cause of duplicate SSCCs in a shipment. Assign at packing, verify the first label, and the sequence holds. Shipments leave FOB Xiamen, with CIF and DDP available.

Frequently Asked Questions

People Also Ask

The Mark Is a Data Problem Disguised as Printing

Almost everything that goes wrong with carton marking goes wrong because two documents disagree, not because a line is misspelled. The mark, the packing list, the invoice and the inspection report have to carry the same carton count, the same style codes and the same weights.

Fix the reconciliation first and the printing takes care of itself. For the outer carton the mark sits on, see carton specification for bag shipping. For how those cartons are stacked and loaded, see pallet and container loading for bags.