Stamp Types and Their Uses
There are three types of marks that you will see used in the conformance of heat treated WPM. Below is a brief explanation of these marks and where their use is applicable.
The HT mark above is used for lumber that has been heat treated and once this mark is applied, it can be used in the manufacture of ISPM 15 conforming WPM. If a facility re-manufactures lumber to resell, that already has an HT or KDHT mark applied, the re-manufacturing facility must put their HT mark on any material that does not have the original HT mark on it in order for it to be acceptable for use in the production of ISPM 15 conforming WPM by their customer. The re-application of an HT mark is not necessary if the material being cut up is used in house.
The above ISPM 15 mark is should be used on multi-component WPM (i.e. Pallets, skids, boxes, crates, etc.) where the material, it has been manufactured from, has been heat treated. This heat treatment can occur either as lumber prior to the WPM’s manufacture or as the manufactured WPM itself. The important element of this is that the material in the WPM has been heat treated. It is also important to remember that this mark should not be used on individual pieces of wood unless it has been added on to a multi-component WPM.
The above Dunnage (DUN) mark is applied on individual pieces of wood that will be employed as a single piece for blocking and bracing. The DUN mark is meant for an individual pieces of wood and should not be used on multi-component WPM.