Inspect surface roughness finish at high temperature

[awol]

We have been using the Testex tape and dial indicator to measure and validate the surface roughness of steel. The Testex tape has a maximum working temperature of 150F and we need to measure the surface roughness on a slightly curved surface at temperatures of 300 F. If I use a thin aluminum or brass foil and use rubbing to transfer the profile of the curved surface to the foil, will I get a good reading?

 

[JR97]

Seems to me an easy way to verify is to use the foil and tape on a cold surface and compare results. If you believe the foil will react differently at higher temperatures, again run a sample but use foil at 300 degrees, let specimen cool, use tape and compare results.

 

[analogkid2digitalman]

Does surface roughness change with temperature over such a small range?

Just curious as to why- grain structure?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"It's the questions that drive us"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~