Type I versus Type II : I'm a little confused

[drc]

Well, I posted this in another thread, but as the subject came up here. If you wish you can download the free photo authentication guide

http://cycleback.com/course.html

A few points:

1) Photo paper changed over time-- how it was made, what it looked like-- and can often judge what period the paper came from. Also, you can identify the photo process used, which helps date the photo to a period. Different processes were used during different periods.

2) If you don't know, you don't know. For even the top exert, there will be photos where he won't be certain of the date. There's nothing errant with saying you don't know if you don't know. The only problem is if you made up a date.

3) You can know a photo is old, but be unable to pint point a year. Due to the photo process, paper, style and aging signs, you can be certain a photo was from the 1800s, but can't say 1888 or 1881.

4) Stamps are a good way to date photo, and in the past have rarely been forged. However, with the popularity of PSA grading, it's possible stamp forgeries will rise. One of the lessons of photo examination, is you don't date a photo just by the stamp

5) I'm not a chemical engineer, but, ironically, my dad is. Really. Pure coincidence to this thread ... He's a retired chemical and biological engineering professor, and has always been my "chief and unpaid adviser" on scientific issues concerning what I do ... He's a prestigious scientist (or at least a retired one) who I just happen to call "dad"

6) One note on paper fiber analysis and chemical testing of photos: I bet no one here owns a baseball card that has had paper fiber analysis and chemical testing. As someone who's also familiar with authenticating baseball cards, you can't tell me that photos and trading cards are different categories in this respect. If you believe it's impossible to determine the age of a photo without laboratory testing, you have to also believe that it's impossible to determine the age of the baseball cards you own without laboratory testing-- as they are all printed images on paper or card stock. Yet, I'm sure many in this thread are quite confident, and I would guess correctly so, that they own genuine cards.

Of course, many baseball card collectors have black lights and pocket microscopes and compare the glossiness and opacity. In these cases, the collectors are doing their own mini scientific testing. Checking the color of fluorescence under ultraviolet light is dang close to home laboratory text. Having to put that 1971 Topps Nolan Ryan under paper fiber analysis would not only be extreme overkill, but not needed.

Genuine laboratory paper fiber analysis would be reserved for something like a newly discovered unique Babe Ruth card that collectors have doubts about. Similarly, you might do such analysis for a legal dispute involving $50,000 Ansel Adams photos. But it's no more needed for the average ACME News Photos Charlie Gehringer photo than for that 1971 Topps Nolan Ryan.