After learning a little bit about plating, I had discussion with some German stamp collectors relating to plate flaws. It seems they were considering printing/inking issues as plate flaws? Anyway, my position was as follows.
"My only experience with plates and plating is the US Scott 1 Cent Franklin Scott #8 1851-1857 which has many variations. 10 different plates, 200 stamps per plate, so roughly 2000 potential different stamps. Every single stamp is different if you look hard enough, but I would not consider the differences to be necessarily plate errors. Are some plate positions worth more than others? Absolutely, because fewer may have been produced. We simply ID the stamps based on the existing flaws on the plates in the various positions. I don't see why the same logic would not apply to German stamp production? Perhaps they do, and I'm just missing something? As you can tell, I'm not a German stamp expert, just a guy with a bunch of German stamps as a secondary feature to my US collection."
Please tell me that I am not a total idiot with this response. If so, I will issue a humble apology.
Chaulkdust, the philosophical content of your position is quite correct. Comparatively few of the plating marks used to distinguish among the 2000+ positional variants of the US One Cent 1851-1861 stamps are actually "flaws" in the literal sense (i.e., indicative of plate damage: gouges, large cracks, rust spots, pitting, etc.). Perhaps you are dealing with different terminological usage customs between different collecting communities. Instead of "flaws" I would simply use the neutral term "features" (a fiber adhering to a plate that produces a curl can hardly be described as a plate flaw, right?).
I'd amend your statement a bit from the factual standpoint, however. The One-Cent Franklin 1851-1861 issue comprises Scott #'s 5-9 and 18-24, with 12 different plates (including two different states of Plate 1).
I'm not familiar with the nuances of German stamp collecting, however, printing varieties and plate varieties are definitely two different things as viewed by most.
For Classic-era US collecting, a one-time over/under-inking of a part of a plate, that causes some odd blob to appear on a single sheet/plate position, is a freak printing variety. These are fun to find and accumulate, but have little value, usually. These are transient mistakes that get wiped clean for the next printing. Sometimes they are dramatic enough to actually be worth a little bit, but the odd blob or spec here and there usually has no effect on value.
A plate variety is some variation from the desired die/transfer-roll that appears on a particular position on the plate, typically due to some sort of error in the process of entering or finishing the plate. These are consistent varieties, and are collectible. Many are minor, and add little to no value, but some are of course major and are very significant. The key is the plate varieties are repeatable, and are not transient.
I would be remiss if I didn't also mention that there are some printing varieties such as double impressions, printed on both sides, and things like that, which can be quite valuable and collectible. Those tend to be one-time mistakes as well, but the difference is that they represent a true systematic error in the printing process, which makes them more interesting than a simple blob of ink in the wrong place just once.
In their German catalogs, Michel includes this with regard to plate flaws:
Quote: These are defects that occur in the printing form as a result of duplication of the printing block or through wear and tear during printing. They are unchanged through entire printing runs or large partial printing runs. Plate errors are only cataloged if official confirmation is made that there is, indeed, a true plate error and not a printing accident. Furthermore, the aberration must be easily recognizable.
Quote: The following errors are not considered varieties in this catalog: Offset (inverse image on the back of the stamp) Flaking color (with Engraved stamps) Mutilation of an overprint Folded sheet (stamp design partially missing) Double impression of the design Color bubbles, color stripes and splotches Paper wrinkles Register displacement/shift Spots and other printing imperfections Blurred print Miscut and misperforated stamps
This is consistent with what I've generally encountered in collecting Germany.
I see a 'plate' error as one that is repeated with enough frequency as to not be a 'mistake'. A smear or ink blot is a singular occurrence. A cracked plate or even worn plate is a real defect which produces 'errors' until noticed/repaired. That's not to say there isn't someone who will collect just about anything but it's value is not able to be fairly estimated due to a lack of sales experience.
Quote: Are some plate positions worth more than others? Absolutely, because fewer may have been produced.
Technically, stamps from all plate positions of a plate were produced in identical quantities. Some plate positions are certainly worth more because of stronger demand for those plate positions that show desirable features such as plate cracks, double transfers, recutting, flaws, etc.
Yes, Classic Coins, I agree that this is a very interesting line of discussion. It all goes back to how major catalog numbers, types and varieties of a given stamp issue have been identified over the years. In the case of the US One Cent 1851-61, for example, certain features have been collocated to identify "Type I", and lo and behold only one position on Plate 1 Early (7R1E) has these features, so it gets a major catalog number (Scott #5) and is the most valuable stamp of this entire issue. But 7R1E is, all things being equal, no rarer than any other Plate 1E right-pane position, say 24R1E, which is as uniquely identifiable as 7R1E. But it so happens that the taxonomy we use to classify this issue places 24R1E in the "Type II" category, of which there are many more plate positions than there are for Type I. So 24R1E is far less valuable than 7R1E, though it is arguably no more common (in fact, it is possible that there are fewer copies of 24R1E in existence than 7R1E, since attrition would have been more likely to affect the less valuable Type II example than the more renown and readily identifiable Type I). There is an award-winning and very thought-provoking article by David Zlowe in the US Chronicle 242 (2014, vol. 66 no. 2) that deals with this whole problem. Highly recommended.