"MD has been working on terrazzo with a few problems perhaps he can shed some
light"  ......Yes I have ...after pouring 2,000 sq feet to match the historic
orginal it was accepted...liked it so much we poured another 2,000 sq ft that
was rejected...Tear it out said the architect....tear it out said the state
...right stones but wrong back ground color....wrong portland...our background
was too white to match the 75 yr old floor..Mistakes were made all
around...the architect would accept it if the state would accept the state
would accept it if the owner (university) would accept it ; the owner was
treating the terrazzo like you would treat matching histoic fabric or paint;
do not go there...with historic terrazzo.match..you cannot match 75 yr.old
pour with a new pour..end of story.....Here is the criteria       Have the
existing terrazzo anaylized..(sample.).60% white # 1 and 40% white #2 ...4%
red ..4% green # 2% yellow  Marble chips.........take this mix dry and lay it
on the floor...satisfied with that.test..mix a small pour 2x2 with pure
portland or epoxie ....but measure the mix exactly...beware of color additives
as they must be measured in porportion(epoxie more difficult for
color)..B..have the existing portland color checked (as mine was off white
with a green tint) C. after creating say 3 test panels; and you are sure of
your mix that you used, take down with hand grinder using 24 grit..bring up
with wet grinder to 400 grit or if you really want to skate 1800 grit. The
pours are usually 5/8 to 3/8 thick on a monolithic substrate.. Terrazzo is
highly skilled; the big pour must have a final layer of chips added by
hand...it must be rolled with a terrazzo roller 20mmins after the pour...then
snake floated by hand to a 32nd over the brass.( brass must be layed exactly
rock hard before pour )  ..alowed to cure for 3 days...it is labor intensive;
and requires alot of teamwork and attention to detail especially in
complicated mixes....There is more to this procedure but that is proably
enough for now ; if you are involved in approving terrazzo to historic it is
(I repeat.)..more than a color issue: patina of 75 yrs very critical
consideration; a wise installer will often walk away from  clients who treat
this as some other finish...I did not do that ..and learned the hard
way....best of luck...Michael   Davidson    STONE GUILD