ISTA Retesting

What are the requirements for retesting when using an ISTA procedure or project?

ISTA test protocols should be repeated periodically or as necessary to maintain the quality characteristics of the packaged-product on arrival. In addition, test must be repeated whenever there is a change in the product, the package or the process. Some changes are not included in these requirements, but only if the change is not associated with potential performance in any way.

Changes in the product can include changes in:

• Design (configuration, components, accessories, etc.)
• Size/weight (dimensions, shape, mass, center of gravity, etc.)
• Materials (type, construction, fabrication, gage, etc.)

Changes in the package can include changes in:

• Configuration (individual package or unit load, container type and sub-type, style, design, interior packaging, etc.)
• Size / weight (dimensions, shape, mass, caliper, gage, etc.) *Materials (corrugated, plastic, metal, glass, etc.)
• Components (closures, labels, straps, pallets, skids, wraps, etc.)

Changes in the process can include changes in:

• Manufacturing / assembly (vendor, location, automation, etc.)
• Filling (equipment, speed, automation, etc.)
• Distribution system (parcel delivery, LTL, intermodal, etc.)

When there is any doubt as to whether a change will potentially affect performance, retesting should be done. Determining when retesting is required may involve knowing and tracking specification details of both the package and the product, such as new or changed components, materials, interior packaging, closure methods, etc.

Changing the grade of the corrugated board in the box definitely requires retest, even in those situations where carrier regulations imply “equivalence” of two grades of corrugated (such as 200 psi burst and 32 lb. /in ECT grades). In many instances, corrugated from these two grading systems will be different in construction and performance and thus must be retested on a grade change. Basis weights (weight per unit area) of corrugated board constituents have been shown to be good indicators of box equivalence or change. If the basis weights change, even if the board is rated for the same performance a retest is appropriate. It is therefore strongly recommended that the measurement and documentation of basis weights in accordance with TAPPI T410 and TIP 0308-01, FEFCO (European Federation of Corrugated Board Manufacturers) Testing Method No. 10, ISO (International Organization for Standardization) EN536, ASTIV1D46, or other accepted industry standards accompany every packaged-product test where corrugated packaging is involved.

Retesting is also strongly recommended when distribution channels change, as this may mean a different test protocol. An example is the opening of an e-commerce business (to replace or supplement traditional retail distribution) that involves significant shipments direct to customer by small parcel carriers.