I am curious between the difference between synthetic and human gray in units. I currently have 20-40% gray in mine, and specifically asked for synthetic due to using BackToNatural after the unit begins to fade to extend the life. Synthetic gray won't color, but it doesn't behave like human either. What are the benefits/drawbacks of using natural gray in units that need at least 40-50% and up? Does natural gray color that much when using BackToNatural?

McNash,
When we order 40% gray and above the factory only offers real human hair since using that much synthetic gray would not act like natural hair. In fact, we only use synthetic gray when a customer asks for it--regardless of percentage. When you get into gray percentages of 40% and upwards the only way to go is natural. Blending that much synthetic gray with real human hair is a real mis-match. They have different characteristics and behave differently when the wind blows through you hair. Not to mention anything of how synthetic reflects the natural sunlight differently than real human hair. Synthetic gray in small amounts is o.k.--you won't notice the difference. Back2Natural will color the gray.
Regards,
John

John, thanks again for the info. Another question about gray additions: when the order has a gray blend, does the factory have hair pre-blended to set gray increments or is it added as assembled?

It's added as the unit is assembled by hand. This units require a tremendous amount of hand work.