Sherwin Incorporated manufactures each PSM-5 panel to P&W specifications from stainless steel. The panels are .090 inches thick and measure 4×6 inches.
A chrome plated strip runs the length of one side of the panel. Five crack centers are evenly spaced in the chrome strip. The crack centers are raised circular patterns forming a star, or starburst. The smallest crack may appear as a single or dual line instead of a star.
The cracks appear in order of magnitude; the largest being visible with low sensitivity materials and the smallest being difficult to detect with even the highest sensitivity materials. The largest crack center is about 1/4 inch, the second largest 5/32 inch, the third 3/32 inch, the fourth 1/16 inch, and the smallest about 1/32 inch in diameter.
Adjacent to the chrome plating is an oxide grit blasted area, considered “medium rough,” and used to monitor washability and background fluorescence.
There are two versions of the panel.
- Polished – the chrome plated section is polished and mirror-like.
- Grit Blasted – the chrome section has been lightly grit blasted to dull the mirror finish.
While no two panels are identical – crack patterns vary because chrome plating properties and thickness cannot be controlled precisely – each panel conforms to P&WA specifications as confirmed and certified by the Sherwin Incorporated laboratory.