i'd say it would have been the late 60's early 70's
i may have used it when i did some developing and processing (enlarging and printing) with dad's...
As I said elsewhere, I like music from all ages and genres, but it's so nice seeing someone keeping all these great old songs refreshed in our minds....
Thanks Joseph. You're kind enough to watch my guitar videos over on my youtube channel. I thought that would've been enough of MY rubbishy old stuff...