I can only comment as to what we have done since the 1950's in order to
repair and glue ivories.

First, we glue any ivories back on if they are loose.  Sometimes we have
to match them from our huge assortment of old ivories.  We have recently
tried white two-component epoxy for the white keytops.  This does it
white and gives the proper white reflection.

The older way to glue the ivories is that we mix normal white wood glue
with that white colour from a tube which is used in school childrens'
water colour sets (I don't know the English word).  This takes long to
dry but gives a perfect finish, provided that the ivory's back is
completely clean.

To get the ivories white, we use the strongest type of hydrogen peroxide
available from the chemists to bleach hair.  We sponge this onto the
ivories at 1-hour intervals while they are exposed to intense sunlight.
Before this, we sand the whole keyboard (black keys removed) with 600
paper to remove the shine and unevenness.

A dentist repairs the bad chips for us and after all this is done, we
buff the ivories on a buffing machine to make them as shiny as new.

This is the way I was taught by George Schindhelm, a German piano builder-
expert who co-designed and built the Schindhelm brand of pianos before
the War in East Germany, and later in South Africa along with Dietmann.

Bernt W. Damm, Restorer of Automatic Musical Instruments,
Cape Town, South Africa
e-mail:   bdamm@maxwell.ctech.ac.za   Tel/Fax:  +27 21 24 1576
(Member of AMICA & GSM)