Faqs

Summary FAQ's

What is a 90/10 Rule?

This rule means that "90% of all thickness measurements should be greater than or equal to NDFT (nominal dry film thickness) and none of the remaining 10% measurements should be below 0.9xNDFT".

Application practice of recent years appears to have approached the common standard of a 2-coat epoxy system. While different thicknesses are allowed, each layer is usually 160 microns for a total thickness of 320 microns.

"Dry film thickness shall be measured after each coat for quality control purpose and the total dry film thickness shall be confirmed after completion of final coat using appropriate thickness gauges."

The general understanding is that there is no guarantee that the 90/10 rule is perfectly achieved for the entire surface, but that such a sampling method is enough for making a practical judgment. If the sample measurements do not satisfy the criteria, additional spot checks should be taken for any area considered necessary by the authorised coating inspector.