Pigment for Epoxy
This is OPAQUE colorant. (You can't see through it).
At 3/4oz of liquid I don't know how many knife handles you can make but probably more than you have time in year or two. It only takes a drop. I'd guess it will dry out long before you can begin to use it all up. It's cheap enough that it won't break the bank if does.
In the "business" this is called pigment. Knife makers tend to call it dye since they often go to the store and buy clothes dye to color epoxy.
This pigment is formulated for epoxy and won't significantly affect the strength. It is liquid form and 1 drop is probably all you will need for a typical glue up.
To use: mix your 2 part epoxy as you would normally, add one small drop and mix it in. It should be the right color, if not add another drop and mix.
TIP: Color your epoxy gray if you are using it for filler around bolsters to match the steel. Color your epoxy the same color as your liner material to help hide any glue lines.
Use colored epoxy to highlight any file work on a full tang handle.
Use colored epoxy to fill in and highlight any handle sculpting.
Tip: Make colored epoxy "pucks" and use them for spacers in hidden tang knives.