Don't know about brown dye but my 1980 Mercedes had very bad plastic windows in the soft top. I was told that I needed a new top and that they could not be replaced without leaking. I went to a boat dealer and got a bottle of plastic window polish for $8 and the windows now look like new. What the heck, it's worth a try!
Really enjoy our 450SL during the somewhat short summers here in Wisconsin. What a great car!
1980 450Sl "Black Beauty"
2002 C230 Kompressor "Spicy"