A precision Nickel Comparator Plate that conforms to International Standard ISO 8503 and ASTM D4417 for grit and shot-blast surface roughness comparison measurement.

When steel has been blast-cleaned, the surface consists of random irregularities with peaks and valleys that are not easily characterised. Experts have recommended that the profile should be identified as dimpled (shot-blast) or angular (grit-blast), and that they should be graded as Fine, Medium or Coarse with each grade being defined by limits specified in ISO 8503. These characteristics are considered to give sufficient distinguishing features for most painting requirements.

Easy to use, place the Comparator against an area of the test surface. Compare in turn the four sectors of the Comparator against the test surface using the x10 Illuminated Magnifier, placed so that the test surface is viewed simultaneously with a segment of the Comparator. The nearest profile to the comparator determines the grade.

The different grades are defined as follows: 

• ◆ Fine-grade: profiles equal to segment 1 and up to but excluding segment.
• ◆ Medium-grade: profiles equal to segment 2 and up to but excluding segment.
• ◆ Coarse-grade: profiles equal to segment 3 and up to but excluding segment 4.

Supplied in a Protective Wallet.