Sorry guys, been a way for a min.
Here is the darkest visor I did
Here are a few other examples
I can get them darker, but I'm afraid on the bubble visors...lol.
Anyways, the hotter the water, the more dye, the faster it absorbs into the plastic. You can get these pretty dark if you want to. Also, I'm pretty sure Volpin is using a dye bath now too. So, its possible to get them really dark. Like I said, I just get to nevous and take them out, or I get to lazy to wait.
Again, these visors were made of PETG plastic. You'll have to test other plastics to see, but I'm pretty sure its possible. I've seen people use the RIT dye technique on motorcycle visors which is a different plastic then PETG.
Also, I've seen people have success on slightly curved visors with auto tint. the method they use is similar to installing it on a cars back window. I believe they take a heat gun and shape it first to by drape forming the tint over the shape. It's a tricky process and I personally know I'm to clumsy to make it work.
Anyways, good luck guys!
Tony