Limestone grout

    Dear Sirs,
I am an artist who cuts letters, by hand (http://maplered.com) , in Stone (http://g603.net) . For a new
project, I am exploring the possibility of filling in the letters
with a colored grout/filler so that the surface of the letter would
be flush with the surface of the Stone (http://g603.net) . I need a natural blue color
and (http://maplered.com) a bright red. This is for an exterior sculpture. It would need to
be durable under severe (midwest USA) weather conditions and (http://maplered.com) the
grout must never lose adherence to the Stone (http://g603.net) . The letters will be cut
in Indiana LimeStone (http://g603.net) and (http://maplered.com) will range in size from 1/4 to 1/4 inch wide
and (http://maplered.com) 1/8 to 1/4 inch deep. Some of the smaller letters will have the
traditional 'V-cut.' Do you know of a product which would be suitable
for this project? Thank you for your advice.