Quoted from Frax:I am not entirely 'satisfied' with the mirroring on my Shuttle backglass....reason being it's not a true mirror. It's more like reflective silver ink. Now I'm completely ignorant as to the actual processes used on these things, but I can tell it's not the same thing.
Frax,
I'm not going to try to change your mind, as to each their own on judging the "looks" of things. But I can give some technical background on our mirroring, which should help in understanding what you are seeing, at the very least...
It's not reflective or silver ink... it's mirror ink. And there is a difference. Metallic inks are plentiful and cheap, and so are the reflectives. They are commonly used on candy wrappers, packaging of all kinds, and making things "shiny" on products we see and use every day. That is not what we are using. A bona fide mirror ink is a design feat of chemical ingenuity that is rarely found out there in the ink world, and there aren't many options. Real mirror inks are based on polarized metal "crystals" (for lack of a better term) suspended in a very special liquid base - making them into a silkscreenable ink. Looks like light grey metallic paint in the can. Pretty boring at first, and a shock when you first look at it. But the magic happens when the ink is reverse-printed (must be reverse-printed, meaning it's on the BACK of something clear) against glass or acrylic for example. After sitting about 20-30 minutes, the drying process takes a dramatic turn at the last minute...the suspended "crystals" all align with one another (polarize) and form a perfect metal/silver micro-foil. This happens against the glass/acrylic surface - making a perfectly flat layer. Which is why it doesn't work printing ON something, and looking AT the ink. In that case, it would just dry as a light grey ink. It can't polarize...the crystals can't all align... unless it's against a perfectly flat face. Which is why you use it on the back of glass, and view the mirror from the front of the glass.
The stuff is harder and harder to come by. Ours came from BASF Germany. It's approximately $2500 USD a gallon (think a can of house paint) plus overseas hazmat style shipping costs (because of the flammability). Which are outrageous.
The true mirror inks are actually rated... based on closeness to a real silvered mirror (like in your bathroom). Our BASF ink is rated at a 92. A real mirror, of course, is 100.
I can tell you that the Shuttle glasses were at the end of our previous can...which was about 2 years old at the time. It takes some time to get through a gallon. The crystals DO get "tired" over time, and thus shelf life is a factor. From what I see from earlier runs from that can (like the PinBot mini playfields "Bling Edition") the ink mirroring is nearly indistinguishable from a real mirror. Likely the true "92" rating on those. The can was new back then. As runs/time went on, I'm pretty much sure that the mirror results went 91, 90, 88 or so. To be expected, after 2 years sitting in a can.
We've been into a new can since the start of the year, and the mirroring on the EK glass, Elvira, BoP, etc are easily a solid 92+. Perfect mirror, with no slight "haze" effect in the polarization.
Regardless, the stuff is well beyond suitable for the application of reproduction. It's truly what it was designed for, and it works really well.
Quoted from Frax:or if it will actually look like factory mirroring.
Nothing will ever look like factory mirroring. That's because nobody will ever do acid-wash mirroring today in 2014. Not in any printshop environment that I can think of. They got rid of all that crap in the 80's and 90's. It's dangerous, it's volatile, and it's poisonous. The process involves huge acid baths, resists, and lots of hazardous wastes afterward (with heavy metals in solution).
The original process was that every backglass started off as a complete mirror. Yes - your backglass was once an actual backglass-sized mirror that one (pre-production) could literally grab and hang in their bathroom. They did NOT start as blank glass panels. The process was very similar to making circuit boards. To get your mirror bits, a resist was silkscreened onto the back of every mirror panel...with the resist landing in exactly the spots & shapes of where you want the silver to REMAIN. The resist acts as a protective barrier..."sealing in" the silver. Then the panels were sent through acid baths, where the silver was eaten off the glass. The spots where the resist was printed - don't get touched by the acid. So after the baths and a bunch of rinses... you end up with clear glass panels with only bits of mirror remaining. Then the panels went onto ink silkscreening for all the colors BEHIND the mirror bits.
Our shop (and I would assume every screen shop out there today) doesn't have the room, the desire, or the demand (really) to maintain/run an oldschool acid bath system...with all the stormtrooper suits, breathing apparatus, ventilation, and drums of acid, wastes, disposal, etc. It would be a nightmare. Health and safety wise, and environmentally as well.
The above is not to be confused with "acid etched" mirrors (like decorative mirrors for your home). That is a process of etching the GLASS (making it turn matte/white) on the fronts to give decorative patterns to the FRONT of a mirror panel (like flowers, borders, etc). Such effects can also be done by CNC sandblasting.
Hope this info helps. Maybe a little education of learning something new in here for some as well.
KEVIN
Classic Playfield Reproductions
http://www.classicplayfields.com
