Received from Steven Greenfield AE7HD via groups.io at 5/1/2021 15:24 UTC:
Keep in mind that what looks opaque to your eye doesn't matter. What matters is that it blocks the wavelengths that affect the coating.
Many inkjet inks have added UV blockers to slow fading. Typically the photo colors, light cyan and light magenta, are the most fade prone and so are the ones with UV blockers added. I recall reading about tests, but I am unable to find the website. They tested many different shades of colors and found, on their particular printer with the particular OEM inks, a green shade blocked UV the best.
If the printer permits, you might try printing the mask using all colors combined to generate black instead of using black by itself.
73 de Jim, KB3PU
