Print rub resistance testing is useful only when the test condition is defined as completely as the acceptance limit. A requirement such as “no scuffing after rub test” leaves too much unresolved: the rubbing surface, load, number of rubs, sample conditioning, inspection method, and definition of unacceptable damage can all affect the outcome.
For printed packaging, rub resistance is not simply an ink property. It is the observed performance of an ink, coating, substrate, finishing process, cure or drying state, and contact condition. A carton may look satisfactory after printing but show ink transfer, whitening, coating damage, or loss of legibility after packs move against each other in a case. Conversely, a demanding laboratory test may not represent the real contact surfaces or forces in a particular distribution route.
The practical objective is therefore not to find one universal rub-test number. It is to define a repeatable test that represents the packaging risk closely enough to support approval decisions.
Why a pass/fail limit is not enough
Abrasion damage can occur during shipment, storage, handling, retail display, and end use. On packaging, it may appear as scuffed graphics, exposed substrate, transferred ink, damaged varnish, or reduced readability of product information.
ASTM D5264-98(2019) covers abrasion resistance testing of printed materials using a Sutherland Rub Tester, or equivalent equipment, with standardized receptors. ASTM D5181-24 describes abrasion testing using the GA-CAT Comprehensive Abrasion Tester and positions the procedure as a rapid laboratory comparison tool for supplier-customer specification acceptance.
That distinction matters. A laboratory test can compare samples under controlled conditions. It does not, by itself, guarantee performance in every warehouse, vehicle, retail environment, or packing configuration. ASTM D5181 notes that field abrasion can depend on variables including temperature, relative humidity, packing tightness, and other conditions.
A useful specification should therefore state both of the following:
- The complete laboratory condition under which the material will be evaluated.
- The failure mode that the result is intended to control in the finished pack.
If either is missing, a pass/fail result can become difficult to interpret. A supplier may meet the stated number of rubs using one receptor and one conditioning condition, while the packaging fails against a different adjacent surface in transit.
Define the failure mode before choosing the test
“Rub resistance” can refer to several different visible or functional changes. These should not be treated as interchangeable.
For a given job, identify what must remain acceptable after abrasion. The requirement may concern one or more of the following:
- visible scuffing or gloss change on a branded panel;
- ink removal from solid colour, fine type, barcodes, or symbols;
- ink or coating transfer to an adjacent carton, film, label, divider, or shipper;
- whitening, scratching, or fracture of a varnish, laminate, or other protective layer;
- loss of legibility in mandatory product information;
- contamination of an internal or adjacent pack surface; or
- damage that makes an approved appearance standard no longer acceptable.
This definition should be linked to the artwork and packaging construction. A minor mark may be acceptable in an unprinted glue flap but unacceptable across a dark brand colour, metallic finish, regulatory text, or machine-readable code.
Do not substitute an adhesion result for a rub-resistance result. Ink adhesion evaluates how well a printed layer remains attached to the substrate under a specified adhesion procedure. Rub resistance evaluates damage caused by repeated contact and relative movement. A print can remain adhered to its substrate yet still transfer pigment, lose surface gloss, burnish, or abrade when it contacts another surface.
ASTM D5181 indicates that abrasion testing can be used to compare printed inks, varnishes, laminates, substrates, and protective coatings. That is a useful reminder that the test result belongs to the finished construction, not only to the ink named on a job ticket.
Write the test condition as a complete specification
The acceptance limit should apply only to a documented test condition. Avoid specifications that state a rub count without naming the method, equipment arrangement, counterface, and assessment rule.
A practical print rub resistance testing specification should include the following fields.
| Specification item | What to document | Why it matters |
|---|---|---|
| Test method | Named method, edition, and controlled procedure | Different apparatus and procedures may not produce directly comparable results. |
| Test equipment | Tester model or equivalent arrangement | Equipment geometry and motion affect contact and abrasion. |
| Test mode | Dry, wet, wet transfer, wet smear, or other agreed condition | A dry result does not establish wet-rub performance. |
| Contact configuration | Printed-to-printed, printed-to-unprinted, or sample-to-receptor | The contacting surface can change transfer and scuffing behaviour. |
| Counterface | Material, grade, coating state, print status, and replacement rule | Abrasiveness and surface energy vary between contact materials. |
| Load and motion | Applicable load, rubs or cycles, and speed where relevant | These define the severity of the laboratory comparison. |
| Test area and orientation | Printed region, machine direction where relevant, and sample placement | Damage can differ across artwork, grain direction, seams, or coated zones. |
| Sample preparation | Number of specimens, cut size, and handling precautions | Inconsistent preparation can conceal variation. |
| Conditioning | Temperature, humidity, elapsed time, and any post-print or post-coating wait period | Drying, curing, moisture content, and surface condition may affect results. |
| Assessment method | Visual conditions, reference sample, instrument method if used, and evaluator | A result needs a repeatable definition of acceptable damage. |
The relevant full standard and the testing laboratory’s current controlled procedure should be consulted before assigning method-specific settings. It is not sound practice to copy a load, rub count, or conditioning period from an unrelated material, instrument, or customer specification.
ISO 18947-1:2021 provides general rub-testing methods for analogue and digital prints on substrates. It may be relevant where the packaging format, print technology, or test objective does not fit an existing internal procedure. The applicability of any standard should still be checked against the actual pack construction and customer requirement.
Choose a counterface that represents the packaging contact
The counterface is often the most overlooked part of a rub specification. It is also one of the most important variables.
A coated folding carton rubbing against another coated carton is not the same interface as a printed film pouch rubbing against corrugated board. Nor is either the same as a label contacting a release liner, a carton rubbing against an unprinted panel, or a printed sleeve moving against a rough shipper case.
Document the counterface in enough detail for another laboratory or supplier to reproduce the test. Include:
- material type and grade where known;
- whether the counterface is printed, coated, laminated, unprinted, or untreated;
- the side presented to the specimen;
- surface condition, including whether it is clean, new, conditioned, or previously rubbed;
- whether the same counterface is used repeatedly or replaced for each test; and
- whether the contact is intended to represent face-to-face packs, pack-to-case contact, or a standardized laboratory receptor.
Where the actual supply-chain contact is known, use pack-out drawings, nesting arrangements, divider specifications, and shipper information to decide whether a representative counterface is warranted. This is particularly important for tightly packed products, high-gloss surfaces, dark solids, metallic inks, and packs with broad printed faces.
Where the distribution contact is uncertain, a standardized receptor can still support comparison between suppliers or production batches. Record that it is a comparative laboratory condition rather than a complete simulation of distribution handling.
Account for the whole printed construction
A rub-test result can change when any part of the printed construction changes. Treat a change in substrate, varnish, laminate, ink series, finishing process, or curing condition as a potential reason to review the existing approval evidence.
Important variables include the following.
Ink and print process
The ink system, colour formulation, ink film thickness, trapping, drying or curing mechanism, and print process can affect the exposed surface. A dense solid, a fine screened tint, and a reverse-printed area may not respond in the same way. Process control matters because incomplete drying or cure can increase susceptibility to transfer or marking under an otherwise unchanged test condition.
Coating, varnish, and laminate
Aqueous coatings, overprint varnishes, UV-curable coatings, laminations, and other surface finishes can change friction, hardness, flexibility, and the appearance of scuffing. A finish that improves resistance to one contact condition may introduce other considerations, such as cracking at folds, changed gloss, altered slip, or different bonding behaviour in later conversion.
Do not assume that a named coating type will deliver a particular rub result. Confirm performance for the exact grade, application weight, cure or drying process, substrate, and test condition.
Substrate and surface structure
Surface roughness, porosity, coating chemistry, fibre orientation, caliper, moisture content, and board stiffness can all influence the printed surface and how it contacts another pack. A more textured board may hide some visual scuffing while creating a different abrasion interface. A smoother coated surface may make gloss changes more visible even when little ink is removed.
Conditioning and process state
Conditioning should be controlled or explicitly disclosed when comparing samples. Production timing also matters: a freshly converted sample may not have the same surface state as a sample evaluated after an agreed dwell period. If samples are taken at different points in drying, curing, storage, or finishing, a comparison may show process-state differences rather than inherent material differences.
Set an acceptance limit that can be inspected consistently
The most useful acceptance limits describe damage in terms that inspectors can evaluate repeatedly. They also identify the viewing and comparison conditions.
Depending on the job, an agreed requirement might be framed as:
- no unacceptable ink or coating transfer to the specified counterface;
- no visible scuffing when assessed against an approved reference under defined viewing conditions;
- no loss of legibility in identified text, symbols, barcodes, or codes;
- no exposed substrate within designated artwork zones; or
- a measured change below an agreed instrument-based limit, where the instrument, geometry, location, and measurement procedure are specified.
A visual requirement should identify who makes the decision and what reference governs it. This may be an approved production sample, a signed colour and finish standard, or a documented defect panel showing acceptable and unacceptable appearance. Terms such as “minor,” “noticeable,” and “commercially acceptable” should not stand alone.
Agree the sampling plan and retest handling before a dispute occurs. For example, state whether a failed specimen triggers a repeat using retained samples, whether all specimens must meet the criterion, and how results are recorded when damage varies between test areas.
Approve comparable samples and investigate failures
A controlled approval workflow reduces the risk of comparing unlike samples.
- Identify the real packaging contact risk. Review artwork criticality, pack-out geometry, adjacent materials, handling route, and known complaints or damage modes.
- Agree the test method and complete condition. Document the tester, mode, counterface, load, motion, conditioning, sample arrangement, and assessment rule.
- Use production-representative samples. Include the intended substrate, ink system, coating or laminate, and finishing state.
- Condition all comparison samples consistently. Record the protocol and elapsed time before testing.
- Test the candidate and approved comparator under the same documented conditions. Do not compare a wet-rub result from one sample with a dry-rub result from another.
- Record observations as well as pass/fail status. Retain images where useful, note transfer location and appearance, and identify the sample, batch, counterface, and test date.
- Retain reference materials and test records. These support repeat approvals, supplier changes, and root-cause investigation.
When a result fails, do not assign the cause to “weak ink” without checking the construction and conditions. Start by comparing substrate identifiers, ink and coating records, drying or curing state, finishing sequence, sample age, conditioning, counterface material, and packing-contact assumptions. The failure may be caused by one variable or by an interaction between several variables.
A sound specification is therefore bounded: it defines the laboratory condition, the allowed damage, and the packaging decision it supports. If the pack construction, contact surface, finish, or distribution configuration changes materially, review whether the original print rub resistance testing condition still represents the risk.
