How to tell if a 35mm photo slide is an original or a duplicate?

[67mustang]

I have 1000s and 1000s of old photo slides I plan to sell. They are mostly photos of actors, actresses, movies and TV shows. I have included a photo of some slides of Jack Nicholson as an example. Slides are more valuable / desirable if I can say "original" but I don't really know how to tell. Some do say duplicate so that is obvious. Any tips appreciated! Is there a way to tell if a slide is original or a duplicate? Thanks

 

[480sparky]

Promotional transparencies like these are most likely duplicates. The original is kept for the sole purpose of creating those duplicates.

 

[67mustang]

Thanks for the reply. What about a random photo of Jack that you can tell was taken at a house or a Hollywood party for example. It is not made for promotional purposes but is just a photo of Jack being his cool self. Is there any way to tell if they are original? Maybe it doesn't really matter. They are most likely duplicate slides made around the time the photos were taken?

 

[petrochemist]

I believe there were special films sold for duplicating that reduced the change in contrast you'd get if using a standard film. So pulling apart the slide holder & looking for anything identifying the film time MIGHT prove them to be copies. I'm not sure it's possible to be sure they're originals unless you have had the slides since they were taken!

 

[webestang64]

To me those look like dupes. I have made millions of dupes in my photo lab career and we used Kodak Ektachrome slide duping film 5071. If you remove the slide from the mount it will have this number on the edge. But most of the bought "travel" slides people would buy in a gift shop used really terrible cheap duping film. Looks like the ones you have were shot on the Kodak dupe film as the color has held up well.

 

[67mustang]

This slide of Lindsay Wagner had a broken plastic mount so I removed it to take a closer look. Would this one be an original or a dupe? Just curious at this point won't be opening any more up. Thanks!

 

[webestang64]

This slide of Lindsay Wagner had a broken plastic mount so I removed it to take a closer look. Would this one be an original or a dupe? Just curious at this point won't be opening any more up. Thanks!

For sure dupe film. Kodak 5071.

 

[cgw]

This slide of Lindsay Wagner had a broken plastic mount so I removed it to take a closer look. Would this one be an original or a dupe? Just curious at this point won't be opening any more up. Thanks!

For sure dupe film. Kodak 5071.

Yup. Edge codes never lie. Just hope the OP didn't get skinned buying these.