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Rubber durometer not to scratch automotive paint

Rubber durometer not to scratch automotive paint

Rubber durometer not to scratch automotive paint

I'm designing a cover for a piece of equipment that may impact a vehicle.  This impact will be at a speed no faster than 5 ft/s and could be parallel or perpendicular to the painted surface.  This cover will be made of PVC and I get to choose the durometer of that PVC.  What durometer of PVC would scratch automotive finish?  My investigation up to now has determined a Shore A hardness of 75 will not scratch the paint on a vehicle, however, I would like a stiffer PVC than Shore A 75.

Is there a reference that could indicate the hardness of automotive finishes?

Thank you,


RE: Rubber durometer not to scratch automotive paint

My company is reviewing US automaker specifications for paint characteristics.  There are a variety of specifications that cover scratch resistance/hardness.  One OEM uses relatively uncontrollable specifications that state "scrape the panel with a thumbnail" and "scrape the panel with a dime" and there should be no visible scratches.  Another OEM uses a special device with a special indenter with a 2 N force and there should be no scratch.  Lastly, the crock mar resistance test is used by another OEM.  I have seen pencil hardness rating of HB applied to exterior automobile paint.  So take your pick of these not-so-good specifications.  



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