Projecting film means irradiating it with tons of Electromagnetic energy coming from the projection bulb: the visible light we want + Infrared and Thermal on the side, causing our photographic material to experience thermal stresses while being projected. Film must somehow deal with that absorbed energy and thermal expansion is what usually occurs, causing slides to bulge and to deform repeatedly and permanently, developing focusing issues due to now uneven slide surface. There are a couple of ways I see how to avoid this:
AN glass frames
I avoid these because of two issues: 1) AN pattern embedded in the surface of the glass - making it AN glass - is easily visible in projected image, degrading the image quality, especially in flat areas. 2) The sudden fluctuations of temperature causes condensation to occur inside the glass-and-film sandwich - repeat this enough times and watch the mycelium of mold eating your slides away... 3) Glass surfaces oxidate and opaque layer develops on them, - regular cleaning therefore is needed to deliver best projection results - this gets impractical fast. Besides - AN Glass slide mounts just localize the problem, just limiting the bulging. There must be better ways to achieve flat and mold-free slides.
Polyester (PET) base
While performing BW Reversal experiments on the available film stock over the years, I've noticed that some films bulge under the influence of heat from the projection lamp and some don't, but I didn't think to explore this. Forward to today and I'm researching what bases are carrying what 135 film, and I started to put some observations together: there are two transparent base materials out-there: Clear Triacetate and Polyester (PET). Triacetate is your usual and beloved gray base that carries most of the BW negative emulsions out there. But then there's the newest brother - PET. "Mechanically more durable, stable and archival" material, and it clicked: the slides that didn't bulge from the heat must be on PET base!
So yesterday I tested this out, shooting and reversing Adox HR-50 in PQ Universal for the first time. The results I got were nothing but impressive - the sharpness, the detail this stock carries is just insane and I'm hooked! Whilst being blown away, I watched for the dreaded bulging, but it didn't ever occur. Next slide > Waiting > No bulging. Next slide > Waiting > No bulging. Next slide…
And sure enough: HR-50 is coated onto that "flimsy" PET base: impossible to tear, resists bulging and doesn't deform even when left projected for minutes at a time. Archival, smooth focusing experience, no AN glass pattern to speak of and no AN mold to watch developing!
What stock is out there on PET? Because I expect that none of these films listed will bulge:
Adox CMS 20 Pro II
Adox CHS 100 II
Adox Scala 50 / HR-50
Rollei Infrared 400
Rollei Superpan 200
Rollei Retro 400S
Rollei Retro 80S
Rollei Ortho 25 Plus
Rollei RPX 25
Astrum/Svema FN 64, Foto 100, Foto 200, Foto 400
There are at least two films on clear Triacetate to compare this to:
Fomapan R 100 and Ferrania P30: indirect evidence as Film Ferrania doesn't warn about handling this film in subdued light due to the "Light Piping" phenomenon characteristic to PET films - think optical fibre. All others do warn about it.
Must and will verify this as I currently do pay attention to this.
AN glass frames
I avoid these because of two issues: 1) AN pattern embedded in the surface of the glass - making it AN glass - is easily visible in projected image, degrading the image quality, especially in flat areas. 2) The sudden fluctuations of temperature causes condensation to occur inside the glass-and-film sandwich - repeat this enough times and watch the mycelium of mold eating your slides away... 3) Glass surfaces oxidate and opaque layer develops on them, - regular cleaning therefore is needed to deliver best projection results - this gets impractical fast. Besides - AN Glass slide mounts just localize the problem, just limiting the bulging. There must be better ways to achieve flat and mold-free slides.
Polyester (PET) base
While performing BW Reversal experiments on the available film stock over the years, I've noticed that some films bulge under the influence of heat from the projection lamp and some don't, but I didn't think to explore this. Forward to today and I'm researching what bases are carrying what 135 film, and I started to put some observations together: there are two transparent base materials out-there: Clear Triacetate and Polyester (PET). Triacetate is your usual and beloved gray base that carries most of the BW negative emulsions out there. But then there's the newest brother - PET. "Mechanically more durable, stable and archival" material, and it clicked: the slides that didn't bulge from the heat must be on PET base!
So yesterday I tested this out, shooting and reversing Adox HR-50 in PQ Universal for the first time. The results I got were nothing but impressive - the sharpness, the detail this stock carries is just insane and I'm hooked! Whilst being blown away, I watched for the dreaded bulging, but it didn't ever occur. Next slide > Waiting > No bulging. Next slide > Waiting > No bulging. Next slide…
And sure enough: HR-50 is coated onto that "flimsy" PET base: impossible to tear, resists bulging and doesn't deform even when left projected for minutes at a time. Archival, smooth focusing experience, no AN glass pattern to speak of and no AN mold to watch developing!
What stock is out there on PET? Because I expect that none of these films listed will bulge:
Adox CMS 20 Pro II
Adox CHS 100 II
Adox Scala 50 / HR-50
Rollei Infrared 400
Rollei Superpan 200
Rollei Retro 400S
Rollei Retro 80S
Rollei Ortho 25 Plus
Rollei RPX 25
Astrum/Svema FN 64, Foto 100, Foto 200, Foto 400
There are at least two films on clear Triacetate to compare this to:
Fomapan R 100 and Ferrania P30: indirect evidence as Film Ferrania doesn't warn about handling this film in subdued light due to the "Light Piping" phenomenon characteristic to PET films - think optical fibre. All others do warn about it.
Must and will verify this as I currently do pay attention to this.
