Why Is There A Difference Between A Regular Blk And A Plate

ilzho "I have a lot of 1930-50's plate blks and regular blks of 4 or 6"
If you have PBs from the 30's, some of them may be worth more than some have suggested. Its after WWII that the vast majority have little if any premium.

I used one specimen from each of my blocks to fill in my album, the rest are for postage. I may group a bunch of mint singles for sale or for enthusing some of the local scout troops into a stamp merit badge after I get a club started. I have bazillion used on and off paper for the same purpose.

Personally, I like a full album page over trying to sell blocks

If you get serious about collecting plate blocks, I would suggest looking for a copy of the Durland Standard Plate Number catalog.

You can pick up an old copy on E-bay or the latest edition from the United States Stamp Society.
http://www.usstamps.org/books.html

Collecting a plate block for a stamp can be very inexpensive but collecting all the plate numbers associated with a particular stamp can be challenging. Some of them are difficult to find and can command a premium.

Dan