How do they put images onto glasses? (Meaning the glasses you drink out of.)

When I go to antique shops, they often have lots of glasses from
decades ago (I'm specifically thinking of the numerous Smurfs and
Pac-Man and Peanuts glasses that I see.), so however they're made they
seem to be very durable. I would think that this would not be the case
if the images were just painted on.

I could imagine that some glasses are etched, but you wouldn't see any
color in an etched image.

Are there online shops that will take a graphic I give them and then
send me back a glass with that image on it?

There are several ways to transfer an image.
Heat is the most frequent trick:

Here is a short course in heat transfer:
" Sublimation uses sublimation ink, heat, and pressure to transfer
images to metals, plastics, ceramics, polyester, high temperature
plastics such as Plexiglas, mylar or melamine. Sublimation ink is
unique in its ability to convert from a solid to a gas without going
through a liquid form. (Just like dry ice.).."
http://www.shortcourses.com/how/transfers/transfers.htm


Here is method you can use on Xmass ornaments or glasses, at home
...
2. Set your domestic oven to as low as possible and place the glass or
ceramic tiles into the oven.

3. Leave for at least one hour.
...
http://www.lazertran.com/Xmasproject.html

SEARCH TERMS: image transfer glass


Suitable service to do the transfer for you depends a bit on your location.
It may be best to consult yellow pages or listing such as 
http://local.yahoo.com/
http://www.urlwire.com/news/080604.html
with search terms such as: online service, custom glass printing

Properly applied decals can be very long-lasting on glass.

I put a small decal on the window of my 1968 Volkswagen when I first
got it. The decal is a bit eroded, but it's still there after all
these years.

The transfers are made from low melting point glaze powder. Not silica
based glass, but coloured compounds with amorphous glass state --
still technically glass.

A great link for custom transfers :-

http://www.decalpaper.co.uk/custom.html

As you?ll see, they offer a range from simple rub-on, to glaze type
which are completely permanent.

Best

Hi mxnmatch,

Here's a website which explains how to do it yourself using your
inkjet printer and special "waterslide decal transfer paper".

Waterslide Decal Transfer:
http://www.papilio.com/inkjet%20waterslide%20decal%20transfer%20paper%20media.html

Cheers,
hummer