Spray-on cancels are done through automated machines and sorting equipment and are intended for everyday mail; the pictorial cancels are rubber stamps that are applied by USPS personnel.
The traditional 4-bar first day of issue postmarks are much the same, although there is some automated equipment that does this work.
Here's an example of the rubber stamp first day of issue postmark that was used for the Janis Joplin (Music Icons) Stamp issued a year or two ago:
The DCPs (Digital Color Postmarks) that you buy at a premium from the USPS are laser printed. Collecting DCPs has become quite popular with some collectors, but the fact is that the jury is still out on what the long term result will be in keeping those "collectibles" from generation to generation. The patent suggests that the digital color postmark should remain intact for 20+ years, but no one has yet considered what will happen to them 40, 50 or even 100 years from now as they are passed on to the next generation of collectors. Only time will tell.
There's also a new "First Day of Sale" postmark that some post offices have to identify a new stamp issue (not from the official city).
This USPS brochure is a bit dated now, but it helps to explain things in more detail:
https://about.usps.com/publications/pub186.pdf
Posted 07/15/2015 10:51 pm
