Over the past couple years, I've gotten into shooting medium format stereo images on slide film. It has been incredibly rewarding. I just developed some 36 rolls of slide film and am preparing to mount them in cardboard mounts for viewing in a backlit handheld viewer. I am (re)considering what sort of tape I should use to attach the film chips to the mounts. In the past I have used regular 3M "magic" tape which 3M claims is "photo-safe" on its website. Is this safe for mounting slides? Depending upon the packaging, the Scotch magic tape claims it is photo-safe in accordance with ISO standard 18916. The standard "evaluates possible chemical interactions between enclosures [the tape] ... ...with colour (dye-gelatin)". Although from the context, it seems that it is likely referring to [RA-4] prints, is it safe to assume that the dyes in E-6 film and RA-4 paper are sufficiently similar for the standard to apply to E-6 films? (I mean, both materials are developed by CD-3, right?) I guess I should probably purchase the .pdf of this standard and read it through, but it's quite expensive. Additionally, some packaging of Magic tape makes no mention the ISO standard at all, which does not give me much confidence. Are there multiple versions of Magic tape? I found another thread where it is suggested to use 3M polyester Film Tape 850, more specifically to mask off chromes. My concern is that nowhere on 3M's webpage for this product does it mention anything about being photo-safe, although it does state "Splicing of film, including movie film" as one of its recommended applications. I'm not sure if this means it is safe though, since movie prints often aren't intended to last very long. Just for context, these are the cardstock mounts that I am using (see below). P.S. The paper supplier for the stock I use to make the mounts claims that the paper is acid and lignin free. Is this sufficiently "photo-safe"? Thanks for your consideration.