Each contractor will have different methods of coloring your countertop, ranging from integral coloring, broadcast color hardeners, and acid stainings. Most contractors can custom color match samples. No, the real beauty of using concrete as a material for your countertop is that each cast is unique. It's color, texture and porosity will vary depending on finishing technique, coloring, curing methods, and skill. This is often a debatable topic among our contractors but generally speaking, slabs should not exceed around 8' x 3'.
Oversized slabs are usually hard to work with and are also more likely to crack.
This just means that for large applications seams may be required but they can become a very attractive element of the design. Yes concrete counter tops may and often do get hairline cracking. This really does depend on the method of construction, conditions during the cure,a nd finishing techniques. This natural often adds to the rustic feel of the final product. Most slabs should be reinforced with steel rebar and wire mesh, therefore the hairline cracks do not affect the structural integrity of the slabs.