SCRATCH & DIG Measurements

Inspection Setup:

As specified by Mil-13830A:

Two fluorescent lights with 30 watts each will allow defects both scratch/digs to be seen as small as 20µm and using a 200 watt halogen will allow scratch/digs to be seen as small as 2µm. The light must be about 6 inches away. The distance between the inspector’s eye and the part should be between 14" – 18".

 Measurement Procedure:

The part is held at a 14"-18" distance and rotated 90° during inspection. The scratch/dig inspection causes the light to reflect back to the inspector’s eye and is limited to the clear aperture.

The chart gives the scratch width and digs in microns, per MIL-13830A.

Scratch Width
(μm wide)
Dig Diameter
(x 100µ)
Light Source
80 50 2 Fluorescent
30 watts each
60 40
40 20 Halogen

100 – 200 watts
20 10
10 5
5 2
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