The amount of etching (etch profile) or anchor pattern achieved on a surface during abrasive blasting is necessary to understand given any subsequent applications of a coating such as paint. The peaks and valleys in the etched surface is the anchor pattern on a microscopic scale. Many coatings manufacturers will identify the etch profile for the best adhesion of the coating being used.
The profile is expressed in millimeters, microns or mils. Anchor patterns generally range from 3 mils and lower and is measured by the depth of the ‘valley’.
1 mil = 0.001″
39 mils = 1 millimeter
25 microns = 1 mil
Ensuring the proper anchor profile will provide optimal adhesion of the coating and completely cover the etched surface.
If the anchor profile is too ‘heavy’, the peaks will stick above the coating and lead to failure of the coating with time. If the profile is too ‘light’, the amount of surface area for the coating to bond to in minimized and this results in improper bonding.
The media type and grit size, blasting pressure, distance from the surface, angle of blasting and surface hardness will all impact the final anchor profile.
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