Introducing Press-O-Film HT
Testex is introducing an improved version of its Press-O-Film replica tape.
Press-O-Film HT is formulated for better performance at the high temperatures (above 140°F or 60° C) encountered in the most challenging environments.
While stable at 140°F (60° C), the current film starts to gradually soften above that temperature. The new formulation adds a 12°F (6°C) safety margin.
Other physical properties remain nearly identical except for some loss of agreement where different tape grades overlap. This effect is most noticeable between Coarse and X-Coarse grades. The new instructions will recommend that where the two grades give different profiles, and both profiles are in the range 1.5 to 2.5 mils (38 to 64 μm), those differing values be averaged.
Tape prices will remain the same and in most applications users will notice little change in the product itself. Press-O-Film HT will be sold on a different label but at the same price. The new version will replace the existing product.
In order to bring replica tape profile measurements more in line with digitally-determined profiles Testex recommends a modification to replica tape’s instructions for use. The new procedure is a formalized recipe for acting on our long-standing guidance that “replica tape measurements are most accurate near the middle of each grade’s range”.
Press-O-Film on the old-design tapes can be safely used with the new instructions.
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Press-O-Film Instruction Change:
If a measurement made with either Coarse or X-Coarse grade tape is between 1.5 and 2.5 mils (38 and 64 μm) inclusive, take a 2nd measurement at the same spot with the OTHER grade.
If BOTH readings are in the above range, record the average of the two measurements as the surface profile (peak-to-valley roughness).
Readings made with either grade that are outside this range should be used as is, i.e. without averaging.
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Testex strongly recommends switching to the new (averaging) procedure, but the new tape can continue to be used with the old instructions if user circumstances warrant.
Testex recommends that measurements obtained using the updated procedure be annotated “HT”.
(Older measurements should be annotated “non-HT”.)
Tape Range Illustration
The colored segments mark the primary range for Coarse and X-Coarse grades. The white segments indicate the ranges of Coarse Minus and X-Coarse Plus grades.
The effect of these changes is to make Coarse and X-Coarse grade replica tape measurements more comparable with other means of determining profile over replica tape’s primary profile range: 0.8 to 4.5 mils (20 to 115 μm).
The graphic above appears on each piece of tape as an aid to recalling the averaging procedure.
The identifier "Coarse", on rolls of Coarse grade tape, is printed in red. The identifier "X-Coarse", on rolls of X-Coarse grade tape, is printed in blue.When obtained with a Testex digital data recording gage replica tape profile measurements are compliant with the US Navy’s paperless recording requirement.