English to Portuguese Tech/Engineering Cinema, Film, TV, Drama Telecommunication

I am translating a film about the life of Alexander Graham Bell, the inventor of the telephone. In a particular moment of the movies, Bell says he´s going to use "goldbeater´s skin instead of membrane" in his experiments. Do you know how we can translate "goldbeater´s skin" into Brazilian Portuguese? In my researches, I´ve found out it´s the outer membrane of ox intestine, used as a special parchment product. Could it be "intestino de boi", "couro de cabra", "intestino de carneiro" or is there any expression more specific? Can you help me? Thanks in advance.