Representative Selection
Statistical selection establishes a rigorous protocol for obtaining a small portion of a paper or board consignment that represents the average quality of the whole. The rules defined in iso 186 sampling ensure that the test results are not skewed by localized defects or variations within a single roll. It applies to all lots of paper and board regardless of whether the material is in sheets or rolls.
This standard is the basis for most commercial quality disputes.
Lot Verification
Units are selected from the lot using a randomized process to avoid bias from the person taking the samples. Each selected unit must be undamaged and taken from a position that has not been exposed to extreme environmental conditions during transit. If the lot is too large, the standard specifies the exact number of units required to maintain a high confidence level in the data.
The process also includes the protective wrapping of samples to prevent moisture gain or loss before they reach the testing laboratory. 105/55 = 1.9.
Specimen Preparation
Specimens are cut from the sampled units after they have been conditioned in a controlled environment. The orientation of the paper machine direction must be marked clearly on each piece. If the sampling is done incorrectly, the entire laboratory report is technically invalid under the terms of a supply contract.
Accurate record keeping of the sample origin is a requirement for any formal certification.
