Trimber found residual salt to be a major contributor to the failure of a similar paper mill maintenance coating system through undercutting.  The adverse effect of sodium chloride contaminated steel on the coating life was also reported recently by the Steel Structure Painting Council.
A 50.8 mm (2-in) diagonal scribe was made on one side of each of the salt-fog and Sea Isle panels to evaluate film undercutting.
The evaluation parameters used were surface rusting, surface blistering, scribe blistering, and scribe undercutting determined according to ASTM methods D1654 and D714.
An overall comparison of the average undercutting (U) for the candidate coating systems is shown in figure 4.
The average undercutting from the scribes of duplicated panels was correlated with cyclic salt-fog/freeze exposure time (figures 5, 6, 7, and 8).
The cyclic salt-fog/freeze test using a scribed panel is a more effective accelerated testing regimen for evaluating coating systems than is the UV/condensation test; this is because the former test provided more and quicker blistering, rusting, and scribe undercutting. In most cases, differences in performance could be noted after 1,500 hours of cyclic salt-fog/freeze exposure.
* Undercutting at the scribe of the cyclic salt-fog/freeze exposed panels (R1).
Deputy general secretary Jack Dromey said: "The exploitation of migrant agency workers and undercutting of indigenous workers divides workplaces, damages community social cohesion and fuels racism.
The union believes structural discrimination existed in many parts of the supply chain that provides meat to Tesco with agency workers, overwhelmingly migrant, on poorer conditions of employment, undercutting indigenous workers.