For backglass preservation you have several options. Each has its pros and
cons. These are listed in no particular order.
Clear mylar, self-adhesive--This works well for glasses without any
lifting or flaking ink, but it is difficult to apply. You get one chance to
lay this on wrinkle-free. You cannot remove it. Like all protective
options, you may wish to trim this off of clear areas, but unless you have a
large window it is not necessary. Cover-Your-Glass--This thick, clear goo pours on thick and slow like
honey and takes a week to dry. It is highly flammable and stinks while
drying. It is sticky to the touch for some time and thus can collect bugs
and dust while drying. Because this takes so long to dry you have plenty of
time to work the lifting ink and flakes into place. It sells for around $16
per quart, with a quart doing 2 4-player backglasses. This substance has
one tremendous drawback--If the glass is ever exposed to 10 degrees F, the
CYG separates from the glass taking the now fractured ink with it. This
means the glass can never again be shipped by air or placed in storage where
it may be exposed to cold temperatures. For this reason many collectors
refuse to use CYG. Polyurethane spray or liquid--This is a popular method. Most use
spray application, but be careful that you don't blow any flakes away while
spraying. Some people have mentioned using several brands, including
Varathane. One collector swears by Rustoleum Clear and has used it for
years with no problems. If you try a new type, be sure to check its
application using a bad glass, before potentially ruining a good glass. Do nothing--This is the most popular technique by far. The enemies
to backglass art are number one, moisture, sunlight, heat, and high-speed
Keep the glass dry. Moving the glass into a warm humid house from a cold
wintry day will cause some condensation and will degrade the glass.
When cleaning the front of the glass with glass cleaner be careful to avoid
letting the cleaner reach the bottom edge of the glass--if it does it may
pool in the lift bracket and wick around to the backside and lift the ink
along the bottom. How many backglass have you seen with ink lifting only
along the bottom?!!!
Sunlight does fade the inks. Keep your machines away from any direct
sunlight--even through a window.
Normally #44 and #47 lamps will not damage the ink, but #55 lamps get much
hotter and should never be used in a pinball machine.
You may laugh at my mentioning protecting your glass from high speed
objects, but you would be surprised how many glasses have been broken
because the air hockey table or dart board was too close to the pinball
One final tip about protecting your backglass--If you don't know how to
remove the glass and put it back in the head properly, just leave it alone.
Experienced technicians have broken backglasses just trying to get the glass
in or out of the head.