It is impossible to know for sure, but for most the results are awesome! There are no FDA regulations on tattoo ink and there are hundreds of manufacturers with unique formulations, ingredients, colors, and many artists use a proprietary formula to produce their art. Some colors may require more treatments to remove. Each tattoo fades at a different rate and sometimes a small amount of pigmentation may remain in the skin even after multiple treatments. This is known as ghosting and is generally accepted as the endpoint for tattoo removal. The goal is to remove all the ink in your skin, however some ink colors are resistant. White ink cannot be degraded by any laser. Sometimes because of the metallic elements in the tattoo, the ink may turn darker and become resistant to treatment.