I have the Stern glass, Invisiglass, and AP magic glass on most of my machines. All perform roughly the same - after having seen the voodoo glass in person (though not a real scientific experiment), anecdotally it seems like it is similar in performance. None of the glass will reject a light shining right down on it, but they all do give that “is the glass on??moment which is pretty great

Having said that, I wasn’t paying attention and swapped my STTNG (regular glass) and JJP POTC (invisiglass) recently. I’ve been playing STTNG a lot, and didn’t notice, until I turned on POTC again and it was almost impossible to see the playfield! So you don’t always notice unless you’re specifically looking at the glass reflections

There’s a thread bouncing around where very detailed photos were taken of glass on the same
Machine, and PDI, Invisiglass and another brand were analyzed. They all gave off a very slight tint that was different from one another, so it was assumed that the coating did vary by vendor. The bug is usually stamped by the glassmaker AFAIK and not necessarily related to the anti reflective coating - although JJP puts a very noticeable “Invisiglass” bug on their glass.

I cant tell which is which by the naked eye though, other than definitely being able to tell which is regular glass vs not

I wanted to mention I actually think the API Magic Glass is superior to the Stern glass, and the price point is pretty good

and similar performance. I must have had a coupon, I swear I got it closer to $200

Oh snap. QFT

Indeed. I have Stern glass, AP magic glass, and Invisiglass installed. At this point my one game which lacks it (TZ) looks noticeably “reflectly”. It is bothersome to say the least. Voodoo glass would rectify that for sure. The biggest difference I have seen is the minor hue they all seem to add. Invisiglass is a tiny bit on the green side, Stern glass a bit blue. Not sure on the AP magic glass, maybe more red than anything (although this may just be the Houdini playfield)

Some glass makers add this "bug " ( that's what it's called) - usually you don't want it in stuff like pinball, for obvious reasons. If you rotate the glass 180 degrees, the bug will be mostly hidden by the lockbar. It's a lot less noticeable than up there at the top.

Ok wow that sucks

Apparently PDI is coated on both sides, which I was not aware of. Not sure about Invisiglass, but Stern is only coated on one side - I had assumed they were all like this. Perhaps one reason PDI is more expensive, but it obviously seems like overkill if so many people can’t tell the difference.

If I’m not mistaken, Invisiglass is also smoothed on the edges. Not sure if they coat both sides either

Some -Not much. The glass is supposed To help with reflections from inside the game, And some from the DMD perhaps.
But it doesn't block direct Light. Unscrew that Bulb!

This is my go-to: about $13 for a pack of 6

https://www.homedepot.com/p/Sprayway-23-oz-Glass-Cleaner-SW056R/305667042

NO AMMONIA. Very important.

You should flip it just to be sure. JJP games always come with the logo side up