A method of preparing a photochromic-dichroic film comprising a photochromic-dichroic layer, said method comprising: (a) forming a molten thermoplastic photochromic-dichroic composition comprising a thermoplastic polymer and a photochromic-dichroic compound, and forming at least one further molten thermoplastic composition, each further thermoplastic composition independently comprising a further thermoplastic polymer; (b) forming a molten stream comprising, a first molten layer comprising said molten thermoplastic photochromic-dichroic composition, and at least one further molten layer (26, 32), each further molten layer (26, 32) independently comprising said further molten thermoplastic composition; (c) passing said molten stream between and in contact with both a rotating roll and a continuous belt that is moving, wherein said rotating roll rotates in a first direction, said continuous belt moves in a second direction, and said first direction and said second direction each correspond to a same relative direction; (d) obtaining said photochromic-dichroic film from between said rotating roll and said continuous belt, wherein said photochromic-dichroic film comprises said photochromic-dichroic layer, and said photochromic-dichroic layer is formed from said first molten layer, wherein said photochromic-dichroic film comprises said photochromic-dichroic layer interposed between a first further layer and a second further layer, said first further layer and said second further layer each independently being formed from said further molten layer (26, 32); and (e) collecting said photochromic-dichroic film on a collection roll thereby forming a wound roll, wherein said first further layer defines a first exterior surface of said photochromic-dichroic film, and said second further layer defines a second exterior surface of said photochromic-dichroic film, at least one of said first exterior surface and said second exterior surface comprising micro-grooves, and said micro-grooves being dimensioned to allow gas to escape from between overlapping layers of said photochromic-dichroic film residing on said wound roll. (a) forming a molten thermoplastic photochromic-dichroic composition comprising a thermoplastic polymer and a photochromic-dichroic compound, and forming at least one further molten thermoplastic composition, each further thermoplastic composition independently comprising a further thermoplastic polymer; (b) forming a molten stream comprising, a first molten layer comprising said molten thermoplastic photochromic-dichroic composition, and at least one further molten layer (26, 32), each further molten layer (26, 32) independently comprising said further molten thermoplastic composition; (c) passing said molten stream between and in contact with both a rotating roll and a continuous belt that is moving, wherein said rotating roll rotates in a first direction, said continuous belt moves in a second direction, and said first direction and said second direction each correspond to a same relative direction; (d) obtaining said photochromic-dichroic film from between said rotating roll and said continuous belt, wherein said photochromic-dichroic film comprises said photochromic-dichroic layer, and said photochromic-dichroic layer is formed from said first molten layer, wherein said photochromic-dichroic film comprises said photochromic-dichroic layer interposed between a first further layer and a second further layer, said first further layer and said second further layer each independently being formed from said further molten layer (26, 32); and (e) collecting said photochromic-dichroic film on a collection roll thereby forming a wound roll, wherein said first further layer defines a first exterior surface of said photochromic-dichroic film, and said second further layer defines a second exterior surface of said photochromic-dichroic film, at least one of said first exterior surface and said second exterior surface comprising micro-grooves, and said micro-grooves being dimensioned to allow gas to escape from between overlapping layers of said photochromic-dichroic film residing on said wound roll.