Is there an absolutely sure way to tell if you are dealing with silk screen vs decals?
I used to think it could be done by feel, but I'm not sure anymore.

I think I have at least one game with a screened lower cabinet, but the head has decals. Again, based on feeling for texture matching the art.
The backbox art feels too smooth to be screened. Lower cab has tons of texture.

Also, for powdery light white mildew, clean with naptha, white vinegar, or 99% alcohol?
Concrobium definately does not work based on experience.

What about on the sides of the head?

Any advice regarding white mildew removal? Is it even possible to get rid of it permanently?
Seems like once it grows on something, it stays forever and will come back with a vengeance any time the conditions support it.

I have some of this stuff on some arcade videogame cabinets. The games are in a line with no space between them, up against the finished basement wall. The mildew likes to grow on the back and sides where you don't usually see it, until you have to move the game for some reason. Then you get to see what it has been up to.

Every time I see it, I spray it with Concrobium mold killer, and wipe it off.

The mildew always comes back, so I know that crap doesn't work. And it's over $10 a bottle.

I have not tried anything else to kill it for fear of making matters worse. Obviously bleach is bad for side art, and supposedly won't work on wood anyway as the spores are already embedded into the porous surface.

We run two dehumidifiers down there year round, at least until the coils freeze up solid come November.

I don't know what else to do, this is getting pretty frustrating.

Any suggestions?

How about naptha for cleaning up mildew?