Hi all, Kim Bunker here.  Replacing ivory keys is really easy!
First of all if you need to have a source of obtaining original
ivory tops and tails.  Usually you get these from a piano rebuilder
or someone who replaces keytops for piano dealers.

you can try to get as many as possible, understanding that ivory color
varies in shades.  I've noticed in the 28 years of matching these that
there are around 9 different shades and 4 levels of quality.

In choosing the number of keys you wish to replace, think in terms of
quality opposed to number of replacements.  If some are still on and
badly yellowed or cracked, remove them with a single edge razor blade.

Now write down the keys being replaced example: 2-C, 2-D, 2-E, 4-F,
1-G, 3-A and 2-B; the total number of key to replace = 16.

The reason that writing down which keys and how many to replace is so
important is that most all ivories are beveled at the back of the ivory
wafer.  For example, all C keys are beveled on the back right side,
all E keys are beveled on the back left side, and so on.

Once you have selected the correct keys for replacement, prepare the
base of the key (the wood part) for gluing of the wafer.  Scrape it
with a single-edge razor blade, pulling towards you lightly until the
top is level.

Then get some "White Out" (liquid paper) because when it dries it is
porous like ivory.  The next step is to get some Krazy Glue.  Draw an
"S" on the base of the key on top of the "White Out."  It will stick,
and then carefully slide the proper keytop wafer on until it reaches
the ivory tail.

Quickly wipe off the excess glue and hold down the ivory wafer firmly
for 30 seconds.  If you wish to make it level with the tail you can
sand the top with 220 grit tri-mite paper until both are level.  Then
using Brasso polish the key to your desired luster.

The one disadvantage of using hide glue (water-based) is that ivory
is a porous material and will warp if you do not have a perfectly flat
piece of metal or wood clamped to it during the long drying time,
usually about 30 minuets.

The process I'm telling you about takes about one minute per key,
if you have all the materials usually found in the office desk!
It is clean and looks like it was done by a pro.

Thanks for now and happy ivory keytopping!

Kim Bunker
http://www.playerpianos.com/