resin coated paper

...It consists of three layers: the support, the emulsion layer, and the protective layer. Traditionally, the support was made of the base paper itself, and baryta paper, which is made of the base paper coated with a baryta layer containing barium sulfate (baryta), gelatin, hardeners, etc. on the emulsion layer side. Recently, however, resin-coated paper, which is made of resin such as polyethylene that covers both sides of the base paper to prevent the base paper from absorbing water, has been used more frequently to simplify and speed up the processing process. The baryta layer is important for increasing reflectivity and gloss and improving the gradation of photographic images, and in the case of resin-coated paper, the titanium dioxide contained in the polyethylene plays an important role in increasing reflectivity and gloss and improving the gradation and resolution of photographic images.

*Some of the terminology that refers to "resin coated paper" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…その構成は，支持体，乳剤層，保護層の3層からなる。支持体は従来，原紙そのもののほかに，原紙の乳剤層側に硫酸バリウム(バライタ)，ゼラチン，硬膜剤などを含むバライタ層を塗布したバライタ紙baryta paperが多く使われてきたが，最近は処理工程の簡易迅速化のために原紙の表裏をポリエチレンなどの樹脂で覆い原紙が水を吸収しないようにしたレジンコート紙resin coated paperが多く使われている。バライタ層は反射度･光沢度の増加，写真画像の階調の良化などにたいせつなもので，レジンコート紙の場合は，ポリエチレンの中に含まれている二酸化チタンが反射度･光沢度の増加，写真画像の階調と解像力の良化に重要な役割を果たしている。…

※「resin coated paper」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報