Type Of 1930-31 Issues Rotary Press Printing Postage Due Stamps.

Ok people here are two examples of postage due stamps which do not match dimensions called out in the Scott's specialized Catalog.Yes there are some other sites that post alternate dimensions ( The Swedish Tiger and so on) however the 2 examples posted here, J82 & J83B are out side the Scott's listing. They are as follows ,J82 and 83B SB 19 x 22 1/2. Is 19.40 x 22.9 mm and the J83B 19.47 x 22.75. Now these measurement where taken on an optical comparator which allows me to precisely measure any sort of item including vignettes. . Any input on this appreciated. A variant?

Scott rounds it's perforation measurements. Measuring designs usually ends in more questions than answers for the most part given that we are talking .5 mm and less differences here.

Ham and Egger's dimensions are of the image size the have nothing to do with the perforation rate.

It hard to tell from your image, but I suspect you have found dry-print dues from the very late 1950s, which would not have any paper shrinkage during the printing process - and thus be larger. I hesitate to say what exact Scott sub-number because Scott has changed the numbering of these at least once or twice in the last decade (and several years of the Specialized have errors in the due listings, which they have been notified about).

Here is an image I made several years ago showing compound perforation dues (J80+), It does not show the colors as well as I had hoped, but:
dull carmine of 1931 to about 1943
scarlet from about 1943 to 1958, a war-time change
the dry-print scarlet of c1958-59.

The three printings can be identified by eye (so put the ruler away). The ink of the dry print is slightly bubbly like a thermograph print, especially in the ovals at the bottom - in addition to the whiter paper.

Paper also grows and shrinks with its moisture content (in relationship with the paper grain). Soak a stamp, measuring out to two decimals points; then place in oven at low temp and dry it completely out, then remeasure.

And be leery about using scanned images, the CCD on scanner is in the middle of the platen and uses a lens to reach to the edges of the glass (lens = 'fisheye'). So the middle of the platen is accurate while the outer edges are dimensionally distorted.
Don

I would echo Don's post. I worked for a scientific research company in the 1990s and we did some detailed paper measurements. Different samples had to be acclimatized in a constant temperature/humidity chamber for 2 days before we would take measurements to be sure we were comparing apples to apples. I think it was 50% humidity at 68 or 72 degrees F.

There is no way the BEP production rooms got every inch of every roll/sheet of paper to the same dampness for printing and the same dryness for gumming and perforating day after day, week after week, season after season. Some natural variation must be expected and we have to use all our senses today to properly identify some of these stamps.

Please ignore my reference to perforations in my comment above. Just as one should not drink and bid one should also not wake up and immediately post pre-coffee. I just cannot wait to see what happened overnight on the SCF!!!

I am not a chemist or lab person in any respect. I do have access to some great optics for inspection .This post is just an observation checking the items. These items have been exposed to the Fl. humidity for years yah de yah. The end result is a much larger than stated design? Thanks for the constructive input.