Here is the essence of what the final rule (16 CFR Part 1107, Testing and Labeling Pertaining to Product Certification Regarding Representative Samples for Periodic Testing of Children’s Products) says.
In order to ensure continued compliance of children’s products produced, the Commission has taken the approach of requiring the manufacturer/importer of record to have knowledge of how tested product samples are similar to untested product samples.
The manufacturer/importer of record can demonstrate this knowledge by; results from prior testing (product has been tested several times with no issues of non-compliance), detailed knowledge of the product itself (in design and material sourcing), the production processes used in the manufacture of the product, the quality control processes used in the production of the product and the production testing plan for the product (testing done at the manufacture site to ensure continued compliance of the product).
So long as the manufacturer/importer of record has a rational basis for demonstrating the similarity of the untested product samples to the tested product samples and documents this rational, then the manufacturer/importer of record is said to have met the requirements in the final rule.
Numerous times the Commission has stated that manufacturers/importers of record are required to know about their products and the manufacturing processes used and implement a testing program accordingly which includes the ability to provide a basis for inferring the compliance of the tested product samples to the untested product samples. Without this basis the testing done by the manufacturers/importers of record on their products would serve no purpose other than to demonstrate the compliance of the tested product samples and not the entire population of product samples.
Manufacturers/importers of record can use “process” to show that the product samples selected for testing are like the untested product samples. For example, a process that manages the lots or batches of raw materials used in the manufacture of children’s products (like surface coatings or resins) can be used as a basis to demonstrate the homogeneity of the population of products with regard to chemical testing for lead and phthalates.
Another example would be a process that creates uniformly spaced holes in the crib rails for the uniformly constructed crib slats which can be used as a basis to demonstrate the homogeneity of the population of products with regard to the component spacing test of ASTM f1169-10.
Without this documented basis, mere testing alone is not sufficient to infer compliance of the untested product samples and as such would not meet the minimum due care requirements of 16 CFR Part 1107.