When selecting a color from the color charts most colors are pretty true, and some are a bitt lighter. The color is added in the last two coats of the process. Our finish is still sponged and therefore not uniform, you can still see some variations in the color which is unique to all of our products.
However, when selecting an acid tone finish you should know that acid is unpredictable. The results could be different than the color chart, and adding more is not guarantee to deepen the color. Acid is uneven by nature, and will keep reacting with the cement until neutralized and sealed.