• surface roughness "Type G" for grit blasting ( sand blasting )
• conform to the requirements of internal Standard 8503 Part 1 
  Roughness comparison sample for profiles after blast cleaning with shot abrasives
• with four different roughness ranges with indication of roughness values:
  Segment 1: "fine" 23 - 28 µ
  Segment 2: "medium" 50 - 70 µ
  Segment 3: "coarse" 85 - 115 µ
  Segment 4: "very coarse" 130 -170 µ
• this comparator has been electroformed in high purity nickel from a mild steel Master Coupon
  whose segments meet the requirements of ISO 8503 Part 1 when measured by the methods prescribed  
• This comparator is only applicable for blast cleaned surface tor Sa2 ½ and Sa3 cleanliness standard
• allows every user to instantly obtain reliable test results for touch and visual comparison
• size: L x B x H = 85 x 85 x 3,15 mm
• weight: 0,060 kg
• in leather case

Application of comparison samples after blasted surfaces according to ISO 8503-1:

Select the appropriate surface profile reference comparator to ISO 8503 ( Order-No. 921.217 Roughness specimens
to "shot blasting Type S" or Order-No. 921.218 Roughness specimens to "grit blasting Type G")  and place it against
an area of the test surface. Compare, in turn, the test surface with the four sectors of the comparator directly or by
using a hand lens with magnification not exceeding X7, placed so that the test surface is viewed simultaneously with
a segment of the comparator. Asses the profiles on the comparator that are nearest to the profile of the test surface and,
from these, determine its grade.

Fine Grade: Profiles equal to Segment 1 and up to but excluding Segment 2  

Medium Grade: Profiles equal to Segment 2 and up to excluding Segment 3  

Coarse Grade: Profiles equal to Segment 3 and up to excluding Segment 4