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Surface Finish

The Tagnite coating is smooth and does not appreciably increase the surface roughness of the magnesium substrate. Like HAE and Dow 17 anodize, surface roughness will increase with coating thickness.

Below is a table which shows the average roughness height (Ra) in microinches of a series of test plates coated with various thicknesses of Tagnite, Dow 17, and HAE anodize. Prior to coating the test plates, each plate was machined, lightly sanded and, when measured by a profilometer, had a surface roughness height (Ra) of less than 20 microinches.

When viewing the chart it is important to note the coating thickness column. Some of the thick HAE and Dow 17 coatings were applied to a thickness more than twice that of the Tagnite samples. Had they been applied to the same thickness as the Tagnite coated plates, they would have had a smoother measured surface.

However, when viewing the thin-coated samples it is clear that Tagnite is substantially smoother than HAE and Dow 17. The HAE coating clearly is the roughest coating followed by Dow 17. However, even when the Dow 17 coating is thinner than Tagnite, as is the case with plate 2 compared to plate 1, it is still results in a rougher surface.

Plate No.


Average Surface
Finish Ra
1 Tagnite ZE41A 0.42 48
2 Dow 17 ZE41A 0.25 57
3 HAE ZE41A 0.37 180
4 Tagnite AZ91D 0.42 35
5 Dow 17 AZ91D 0.56 95
6 HAE AZ91D 0.40 130
7 Tagnite ZE41A 0.79 53
8 Dow 17 ZE41A 1.91 187
9 HAE ZE41A 3.53 240
10 Tagnite AZ91D 1.03 79
11 Dow 17 AZ91D 2.90 180
12 HAE AZ91D 3.18 440


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