The Tagnite coating is smooth and does not appreciably increase the surface roughness of machined surfaces commonly found on matting faces of aerospace parts. Unlike HAE and Dow 17 anodize coatings which do significantly increase surface roughness.

The table below shows the average roughness height (Ra) in micro inches 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.CoatingAlloyCoating Thickness
Average Surface
Finnish RA

2Dow 17ZE41A0.2557

5Dow 17AZ91D0.5695

8Dow 17ZE41A1.91187

11Dow 17AZ91D2.90180