Rubber durometer not to scratch automotive paint

[cooperjer]

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,

cooperjer

 

[CoryPad]

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.

Regards,

Cory

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