Riverside Stamps

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A study of the differences between the 1922-25 perf 11 flat plate issues and the 1923 & 1931 perf 11X10 1/2 rotary press issues.

A lot of you may be wondering why I'm doing a study like this - in a nut shell it comes down to differences in opinion. I was going through my collection double checking for correctness when I came across a 1922-25 flat plate issue perf 11 5c Roosevelt (Scott #557) in the 1923 perf 11X10 1/2 rotary press issue 5c Roosevelt (Scott #637). Since it was an extra I decided to sell it on eBay. The stamp sold, it was sent to the buyer and a few weeks later I received the stamp back with a note stating that it was a #637 not a #557 please refund my money. Of course I refunded the money all the while thinking 'how the heck could I have mis-identified the stamp?' so I rechecked the stamp and I can't make either the right or left side line up with a 10 1/2 perf gauge but it sure lined up really well with the 11 perf gauge. Undaunted the next time I was at auction I gave the stamp to a total stranger and asked if they would double check my identification for me. Much to my surprise the gentleman stated that it was #637. When I got home that afternoon I rechecked the stamp even more carefully then the last time and again I could not make either the right or left side line up with a 10 1/2 perf gauge but the 11 perf gauge was a perfect fit.

Below is a picture of the stamp in question:

 

There are three characteristics that I looked at that could be used to distinguish between flat plat printed stamps and rotary press printed stamps and they are:

  1. Image height (1/2c to 15c) and width (20c to $5).
  2. Gauge of the perforation of the long side as gauged by the Specialty Gauge for Bureau Issues found on the Precision US Specialty Multi Gauge (copyright Sonic Imagery Labs)
  3. Appearance of the gum on unused stamps.

I gathered up all of the stamps from these two issue dates that I could get my hands on and measured the longest part of the stamp image down to the 1/4mm, measured the perforation gauge on the above mentioned gauge and noted the appearance of the gum on all of the unused examples. Below are the results of all that measuring.

For flat plate printed stamps:

  1. The longest side of the image measured from 22mm to 22 1/4mm.
  2. The gauge of the perforations on the longest side are 11-72 to 11-72.5.
  3. The unused examples had gum that was smooth over the whole back with no gum ridges or gum breakers.

For rotary press printed stamps:

  1. The longest side of the image measured from 22 3/4mm to 23mm.
  2. The gauge of the perforations on the longest side are 10 1/2 - 75.
  3. The unused examples had gum that showed gum ridges and gum breakers spaced 5.5mm to 22mm.
 

From the above analysis it can be safely said that there are indeed major differences between flat plate printed stamps and rotary press printed stamps. The longest side of a rotary press stamp will be longer by up to 3/4mm, a perf 11 gauge stamp can't be made to fit a 10 1/2 gauge or a perf 10 1/2 gauge stamp can't be made to fit a perf 11 gauge and a rotary press stamp will always show gum breakers were a flat plate stamp will have a smooth over all appearance.

Now back to the stamp in question, how does it stack up to the above criteria?

  1. It measures 22 1/4mm on the long side of the image.
  2. The perforations on both long edges measure 11-72.
  3. The gum over all has a smooth appearance with no gum ridges or gum breakers.

Base on the measurements the stamp in question can not be anything other than a Scott #557 perf 11 flat plat press stamp.

To Contact Riverside

To Contact Riverside Stamps:
Email:
Mike Girard - Owner / Operator / Web Master: g1rardmn1099@comcast.net


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