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Posted Sep 24, 17 16:40 by Ken Lawrence (kenlawrence)

Once again, direct comparison of perforations with a reference stamp is the preferred method of authentication, not of measurement.

As to measurement, aside from the cumbersome aspect of indirectly detecting, electronically processing, and attempting to reproduce a linear quantity that can easily be observed and measured directly, an inexpensive scanner is not an accurate measuring device for the same reason that my scanner cannot accurately reproduce the lines of the BSG gauge, but only manages to approximate them as a sequence of steps. Even on the horizontal and vertical axes, a digital reconstruction only approximates a line as a series of dots.

I'm aware that digital electronic technology is today's secular religion, but there ought to be limits short of creating a Rube Goldberg universe.

Posted Sep 24, 17 14:44 by Gordon Eubanks (gordon)

Hugh,

Your efforts have greatly benefited US philately.

Thanks!

-g

Posted Sep 24, 17 11:43 by Hugh Feldman (feldman)

Going back to my roots

Hi Richard and all users of this great board,

having finally seen my book on the USPD contracts for carrying mails within the US by railroad published, I have been looking for another subject area to tackle. I am afraid, that as my fiscal circumstances and the effects of Anno Domini now preclude long periods of time in Washington DC, I have decided to research archives that are a little nearer to home.

As a founding patron of the Postal Museum (the British one), I have the advantage of being able to access material that may remain hidden to others, this has led me to a subject area that is not far removed from my studies of US mail routes. It is not widely known, even by British postal historians, who have written about the GPO from its early days, that since the record books of the 1680s, the mails on the post roads from London, as well as the slightly later cross and by roads, were carried by contractors rather then GPO employees. I am now embarking on both a research project and the collecting of artefacts related to these contractors and their routes. I intend covering the period 1687 to 1840, this covers two major periods of change, from waggon and horse to Palmers stage coaches of 1794 and then the move to railroads. I reckon it will keep me busy for the duration.

I would like to thank both Richard and all my friends from this board who have so kindly helped me in my previous efforts and hopefully, some may find the research that I will be doing at our own archives in the UK of interest.

Posted Sep 24, 17 8:59 by Glenn Archer (archerg)

Perf measurement by computer imaging.

Thanks for your input Ken. We do have some opportunities to streamline our imaging and cataloguing process. Your suggestions are good and I have proposed similar ones informally.

At present we use our Foster Freeman VSC-6000 for such measurement tests, and hundreds more analyses, where there is suspicion or a difference of opinion. Our capable analyst (Garfield Portch) is busy from the get-go on an expertizing day, and there is frequently a large backlog of requests. Few tests are routine or quick.

Posted Sep 24, 17 8:15 by Ken Srail (kensrail)

Glenn, if a highly-accurate gauge measurement is required, I think it would be hard to beat a high-resolution scanner.  You'd have a level of precision that would easily beat someone's eye looking at a hand-held gauge, no matter how stable the substrate.

Known measurement standards could be scanned periodically for calibration, and it should be possible to measure perf gauge to 0.001 or maybe even 0.0001 (putting the absurdity of such a measurement aside for the moment.)  Scanners are inexpensive, software is low-cost (actually free for the pixel counting required), and a decent scanner would have many other potential uses in the expertizing process beyond measuring gauge.  Have you considered something like that?  (BTW, I agree with others that direct comparison with known genuine examples is far more desirable than measurement with a gauge.)

Posted Sep 23, 17 17:40 by Ken Lawrence (kenlawrence)

Dave S.

Overpayment or double rate.

Posted Sep 23, 17 16:43 by Ken Lawrence (kenlawrence)

Bob Mustacich's first footnote recorded the gauges under discussion here.

Image

Posted Sep 23, 17 16:27 by Ken Lawrence (kenlawrence)

For authentication, direct comparison with a genuine reference stamp is the preferred method. That is no use if you are attempting to measure the gauge of the separations, and of little use if you are attempting to identify a variety that is a near match.

In many instances measurement is the best place to begin even if the final requirement is authentication, especially because most fake perforations applied to simulate expensive United States stamp varieties were applied by metric tools that are easy to detect with a Kiusalas gauge. (Unless you employ the careful method that Larry Weiss elaborated in the BIA booklet on perforation measurement you will experience the results Mike Girard reported.)

Besides inventing and publishing the extremely accurate United States Specialist Gauge, Richard Kiusalas was a notorious faker of perforations. The 11-73 scale on the Kiusalas gauge is not a genuine BEP spacing, but does match the perforations on fakes of Scott 544 rotary sheet waste stamps that Kiusalas falsely described in a published article as "experimental," but are actually altered Scott 486 rotary press vertical coil stamps.

John Barwis's link to Bob Mustacich's article is valuable because the author has developed an entirely different technique of measurement and authentication. Take note that he has applied his technique to the varieties that Bob Kitson specified in the references I recommended earlier.

Posted Sep 23, 17 14:05 by Dave Savadge (nomad55)

For Ken Lawrence

Thanks for your suggestion regarding my San Diego cover. Even though the flap was stuck down, I was able to carefully open it with some of my wife's sewing tools. No sign of being sealed, just stuck probably from pressure and/or heat. Therefore, I conclude it's a one cent overpayment of the third class rate.

Posted Sep 23, 17 13:25 by Barry Jablon (friday)

Accuracy and variability

The 3 cent Pictorial is rarely measured to three decimal places, in part because we don't know even the metric used by the printer. To answer my own question posted yesterday, the image size of the 114 is either 20.5mm wide by 20.25mm high or 13/16ths of an inch by 25/32nds of an inch: no record remains of how the diemaker measured it. I'd appreciate hearing if anyone has better info on this.

Posted Sep 23, 17 12:34 by Mike Girard (reywest1)

Accuracy and Variability

I’m a little late to the game but here’s my two cents.

I agree with John W. also. Many moons ago when I was teaching myself how to expertize Washington/Franklin coils I noticed that the perfs on the gauge 12 coils sometimes did not match up precisely with 12-66 Specialist gauge even though the coil was genuine. Just for giggles I measured all the perforations of a perf 12 block of four using an Instanta gauge and found a narrow distribution of measurements that I recorded on my website here.

At first I attributed the variations to perforation wheel tolerance but after reading a few articles about paper shrinkage I realized that was probably the biggest factor in the variations in perforation measurements especially in the way sheet stamps shrink a bit in the horizontal direction.

Reposted with correct web address I hope, still trying to get used to posting on the board.

Posted Sep 23, 17 12:21 by Nick Kirke (nick kirke)

Peforations

My word, we are making this sound difficult. For me, one of the greatest pleasures as a boy was going thru literally thousands of Washington/Franklin stamps in dealers stocks looking for those magical perf 10s and 12s. As it happens I soon learnt the quickest way  to compare, was lining up a known perforation to assess others. I was chuffed at this diligence - I liked to think it was a first indications I wanted to learn more about stamps other than their colour and denomination. My engineering skills were at the level of being able to mend a puncture on my bike or hammer a nail in straight - and they remain at that level.

Posted Sep 23, 17 12:18 by Glenn Archer (archerg)

Thanks for the welcome

Thanks Richard,

We have an extensive reference collection on-site to which we can, and do, refer. Our meetings are held in the research library, so all the literature we could ask for is at-hand. I can fully appreciate the "pooled ignorance" comment; truth is, it's a good committee and we flush out a lot of weeds and doctored stamps/covers amongst the good stuff. My little side-project request here is of my own volition, an attempt to upgrade a standard.

Posted Sep 23, 17 12:11 by John Wilson (vladivohaken)

NIST certificates

We both know what a NIST Certificate can cost.....but on a slightly more serious note, and accepting that there are serious misgivings about the efficacy of perf gauges for expertising, what we need is someone with our combined engineering backgrounds but who is still in regular employment, who might be willing to do laser engraving on genuinely stable substrate for free - to the benefit of the whole hobby. Is there anyone listening??

On Richard's observation on comparisons; in the electronics industry we used comparison machines that compared a good printed circuit assembly against production units. Two images were alternated in a single eyepiece and any components missing or incorrectly fitted to the production boards showed up as a flashing "difference" image. This system would work perfectly for comparing stamps - but unfortunately would cost an arm and a leg to buy...

Engineers of the world unite; together we will instil sanity and truth.

John W.

Posted Sep 23, 17 12:05 by John Barwis (jbarwis)

Measuring perforations

Those interested in this subject may wish to read "Measurements of Stamp Separation Features by Digital Image Analysis", by Bob Mustacich, which starts on page 73 of this publication.

Posted Sep 23, 17 11:57 by Glenn Archer (archerg)

Perf Gauge Fun and Games. A first for me

Thanks for the offer - Are they NIST certified and traceable?

I was surprised but by no means offended at Ken Lawrence's offer. That is probably a fair representation of all-in costs. The world market for perf gauges is limited; the proper R&D for a "gold standard" gauge isn't doable on a beer budget.

Posted Sep 23, 17 11:43 by John Wilson (vladivohaken)

I didn't know that

Glenn,

I use my old original Instanta which has, as you say, the lines engraved on the under surface. If SG are now printing lines on the top surface then they have added significant uncertainty to the measurement - a bad mistake.

But hey - I just found a stash of 12 "old Instanta" gauges, so someone make me a serious offer.

John W.

Posted Sep 23, 17 11:30 by Richard Frajola (frajola)

Expertising Perforations

Glenn,

A belated welcome to the board!

I have always considered any perforation gauge to be worthless for expertising. I would think direct, physical comparison with a known genuine example is the only way to expertise perforations, or perforation varieties.

Nothing really is as useful as a genuine example in comparing perforation hole formation as well as the other physical characteristics. Ten people compariing a patient with a known genuine is betetr than each having their own "standard" using any perf gauge. (all this a variation of my old "pooling ignorance" complaint about some "expert" groups)

Posted Sep 23, 17 11:29 by joe kirker (centuryc3)

Instanta Perf Guage

Glenn

Put me on the "wanted to acquire" list for your (hopeful) new Instanta Perf Guage. Hopefully the final cost will be around $10!!

I'm foregoing any attempt to be on Shark Tank with the idea of the XYZ Expertizing Service. Let someone else try it----I Don't Care!! Joe

Posted Sep 23, 17 11:14 by Glenn Archer (archerg)

A Poke in the Eye With a Sharp Perf Gauge

Good morning all

I did not think my original post would incite such a discussion. I thought that perf measurement would rather bore the PH crowd. Feel free to take a poke at me for weighing in now. If I get the gauges I seek, I will be happy.

Does paper dimension change with moisture content, soaking/drying, humidity etc.? Yes, it can, but under normal storage it won't change significantly enough to alter perf measurement.

When one is on an expertizing committee, you have maybe ten members with an agenda of up to 150 items to analyze. Perhaps two or three will look at a given submission and discuss it. We all use an "old" Instanta gauge, our own personal one, as that is the standard. A difference of 0.25 perfs measurement changes the ID of a BNA stamp in many instances.

The issue I see is basically repeatability of measurement, i.e. precision. The $6 SG "new" Instanta can be used to get accurate measurement. The problem lies in its design, which renders it prone to wider variance in results. It is close to a mm thick and its grid is printed on the top, and everyone will compensate for parallax error differently. The old Instanta eliminates this variable, its grid printed at base, but 30+ years on it seems no two have survived exactly the same.

I am fairly confident I know what we need, maybe I should just make a new model, and laser-etch-in the grid rather than print it on. In a previous career, I was also a professional engineer.

Posted Sep 23, 17 10:50 by John Wilson (vladivohaken)

Accuracy and Variability

Nothing is more distressing (to an engineer) than uneducated statements of “fact” without supporting evidence. Like Ken Stach, I have been closely involved with accurate measurement, having run a European accredited EMC (EMI) Test House here in UK. Being re-examined on an annual basis, as a person and as a facility makes one acutely aware of the need for “uncertainty budgets” in all measurement disciplines. Handing down statements as though engraved on tablets of stone may have been acceptable from Moses, but things have moved on. (but clearly not for everyone).

Ken, get a copy of NIST Technical Note 1297 “Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results”

John W.

And in the immortal words of Looney Tunes (how appropriate) "That's all folks".

Posted Sep 23, 17 10:48 by Farley Katz (navalon)

Richard Kiusalas

A stamp collector once bought a Kiusalas

He said: "Any other gauge is just useless"

But if the perf machines are not exact

It's an undeniable fact

Using a better ruler is just foolish

Posted Sep 23, 17 10:44 by joe kirker (centuryc3)

Perforation measurement accuracy

Having been following the current discussions on the most consistent and precise measurements for stamp perforation gauging, I can possibly see another philatelic service coming of age.

The XYZ Philatelic Perforation Service could issue measurement certificates on items submitted giving what precise perforation measurement they verify using and consistently verifying their (laboratory room) relative humidity, temperature, and all other possible environmental factors. Perhaps, rather than using any plastic or metal (or cardboard/paper) type gauge, a highly sophisticated system using parallel laser lines between the absolute centers of perf holes in conjunction with precise laser distance between the above lines and some type of cesium atom time measurement for that intersecting line to be reflected back.

Of course all the data would then appear on the issued certificate--with the absolute understanding that any given measurements are ONLY viable until the stamp patient has left the premises.

Anyone want to go on Shark Tank with that idea??

Posted Sep 23, 17 10:21 by Ken Stach (kenstach)

Accuracy and Variability

I, too, am a retired engineer and have studied statistics at some length. Further, I was in industrial manufacturing of bulk chemicals for 35 years. Variability is an issue that is near and dear to my heart!

I find it hard to believe that such accuracy as cited in some posts here can be obtained repeatably. There are simply too many sources of variability:

1.) Variability in the production process 2.) Variability in the product (stamp) 50 or more years later due to paper shrinkage or expansion 3.) Variability in the actual measurement device 4.) Variability between the people using the measurement device in how they use the instrument 5.) Other sources of variability that I've not identified in the four mentioned above.

The TOTAL variability is the square root of the sum of the squares of all the sources of variability mentioned above. Until a statistically significant study is provided that quantifies each of the above sources of variability as a percentage of the whole, I (like others have noted), find it difficult to understand how one piece of plastic can be more accurate than another (for example).

Posted Sep 23, 17 10:15 by John Wilson (vladivohaken)

Perforation Measurement

To repeat the Lawrence statement: "Actually, unused fully gummed stamps are dimensionally stable within the stated and tested accuracy of the gauges described below."

So how stable? Where's the evidence? Don't make statements unless you can support them.

You are "Duckin' & Divin'".

John W.

Posted Sep 23, 17 10:04 by Ken Lawrence (kenlawrence)

Perforation Measurement

Contrary to what has been asserted, we do have evidence to support all these points with respect to United States stamps of the 20th century (incomplete for the 19th, zip for the 21st). Specialist gauges are for detecting minute differences among 20th century stamps that reflect different perforating equipment, for which mechanical drawings exist. 

Our BIA committee's good fortune was that the needs of the Germany Philatelic Society's Buildings Study Group coincided with ours even though theirs concerned subtle differences among comb perforators in the 1948 chaos in Germany while ours concerned differences between and among line perforators, on-press harrow perforators, and off-line stroke perforators used to finish identical stamp prints, which imparted nominally identical hole spacings. Those who don't care about those differences have no need for such precision.

Even more difficult to measure are the differences between large- and small-hole perforations on coil stamps, which reflect different perforators with identical spacings between hole centers. The difference in catalog and market values are sometimes large.

As for the instability and stability of paper, we have more than a century of experiments and reports, including the BEP paper studies of 1909, winter- and summer gum studies, gum breaker studies, and others (not to mention Bob Kitson's obsession with re-measurement of both his tools and his stamps to detect any changes over time.)

These subjects have been studied and reported in the United States Specialist and in research reports for more than 80 years, all digitized and on-line to United States Stamp Society members on the usstamps.org website. I urge interested Board member to join the society and to read them. 

I have no objection to anyone discussing and debating these issues, only to the truculence that seems to animate some of the commentaries.

Posted Sep 23, 17 9:24 by John Wilson (vladivohaken)

We can all speak about stamps

Thank you Richard,

Just for the record; I was studying and measuring stamps and overprints on stamps fifty years ago in collaboration with Gernot Reiners and Robert Gibb when we were writing original research into German West African Colonies. I have nothing to prove, particularly to "pokes in the ribs" from Ken Lawrence. Go poke someone else Ken.

John W.

Posted Sep 23, 17 8:52 by Richard Frajola (frajola)

Stamp Perforation Measurements

I think we can all speak about stamps even if the subject is not our primary interest.

Ken - You are on thin ice with your argument that accuracy of measurement is critical beyond the limits of the Instanta guage. A compensation for the fact that you can't always know all the variables of the genuine perforations. In short, what is the point of knowing the difference to .01mm if the we do not know the production limits of the perforating device (or of environmental changes to the stamp being measured).

I listened too long to Dr. Kornfeld spout his nonsense about how to tell genuine from fake coil stamps to tolerate "scientific" proofs regarding perforations.

Posted Sep 23, 17 8:34 by John Wilson (vladivohaken)

Holes in the argument

Ken states: "Actually, unused fully gummed stamps are dimensionally stable within the stated and tested accuracy of the gauges described below."

I ask "How stable"? Pursuing greater and greater accuracy in the measurement instrument is a mistake typical of a non-engineer. Anyone making the statement above has to justify it by presenting evidence, not the usual torrent of vaguely insulting words.

Show me the uncertainty budget for the paper compared to the gauges mentioned, and don't try to hide from the question. Stop "waffling" and justify the statement.

John W.

Posted Sep 23, 17 8:10 by Ken Lawrence (kenlawrence)

I note that both men have previously derided collecting stamps (Wilson) and holes in stamps (Baird). Those of us who do regard such varieties as worthy of study do need equipment capable of accurately recording the differences. No doubt other collectors dismiss postal history collectors as infantile, but that does not diminish my intense interest in the subject.

If you read Bob Kitson's articles on perforation varieties (for example, between the otherwise identical stamps perforated on the Andreotti press, perforated off-line on the L-perforator, and perforated off-line on the Eureka stroke perforator), you will easily see why the erratic readings of Instanta gauges of different vintages are not suitable to those. Similarly for Julian Goldberg's articles on the perforation varieties on Canadian stamps.

I don't slag your interests. I attempted to help with P-B Schermack holes and War of 1812 information (Baird) and Brazil via LEO transit (Wilson). So why slag mine?

If you want to discuss and debate the usefulness of various measuring devices, I'm happy to do so. For all United States perforated issues before 1977, the Kiusalas gauge represents the gold standard, but it has no scales to measure the L-, Eureka, Goebel, and Andreotti perorations on BEP prints, nor any of the private contractors' perforations. That was where our committee began in the 1980s.

(Today, if you can find a seller, an original Kiusalas U.S. specialist gauge printed on aluminum will typically cost in excess of $100.)

The third member of our committee was George W. Brett, universally recognized as the dean of United States philately.

Actually, unused fully gummed stamps are dimensionally stable within the stated and tested accuracy of the gauges described below.

I have not recommended that anyone here buy any perforation gauges. I responded to a request as best I could, as I have previously done for Misters Wilson and Baird.

Posted Sep 23, 17 6:14 by Jim Baird (bairdo)

Holes in paper & donuts

Mr. Wilson is, of course, correct.  It's all about boys playing in the sandbox.

Posted Sep 23, 17 3:39 by John Wilson (vladivohaken)

measurement accuracy

I too am a retired engineer, accustomed to seeking measurement accuracy, but turn around and look the other way. This quest for absolute accuracy based on dimensionally stable plastic films takes no account of the physical qualities of the material being measured - a piece of paper with holes punched in it. How dimensionally stable is that? Before condemning different plastic materials, where can we see a side by side comparison of the relative dimensional stability of paper vs Instanta vs BSG? To my engineering mind unless the paper is demonstrably more stable than the plastic used in the Instanta, the discussion is futile.

A secondary consideration is why a piece of BSG plastic film is worth more than ten times the value of a Stanley Gibbons piece of plastic?

This is all rather like the National Physical Laboratory designing a temperature compensated titanium ruler to measure the outside diameter of a doughnut.

John W.

Posted Sep 22, 17 20:46 by Ken Lawrence (kenlawrence)

Perforation Gauges

In his "Linn's Multi-Gauge" review in the August 1994 United States Specialist, Larry S. Weiss, chairman of the BIA Washington-Franklin Heads Issue Committee, wrote, "Gauges on plastic are notorious for having problems, particularly due to shrinkage. All periodically need to be checked against a more stable measuring device. The Stanley Gibbons Instanta gauge, which is also marked for perforation measurements by tenths, has also been found to be subject to plastic shrinkage problems. These gauges have been noted to shorten progressively with age."

In the October 1994 issue of the Specialist, my article "The BSG Gauge" and Bob Kitson's article "More on the BSG Gauge" [excerpt below] explained why we recommended it and how to use it to obtain consistent measurements to an accuracy of plus or minus 0.02 gauge.

Larry is a retired engineer; Bob (deceased) was one.

Image

Posted Sep 22, 17 15:53 by Ken Lawrence (kenlawrence)

Instanta

For basic identification Instanta is fine. For specialists and expertizers it's next to useless. If we could have used Instanta we would not have devoted so much time and expense to searching for an accurate gauge. Bob Kitson, who chaired the BIA perforation gauge committee, was a chief engineer for DuPont.

Posted Sep 22, 17 13:55 by Richard Frajola (frajola)

PhilaMercury Digital Rendezvous 2017

Only TEN days left to enter your one frame exhibit!

All those gold dimes (each cost over $250) to the winners ....

Thanks to all those who have entered to date.

Posted Sep 22, 17 13:48 by Barry Jablon (friday)

Perfs

Did NBN use metric or decimal or inch fractions in laying out plates?

Posted Sep 22, 17 13:37 by John Wilson (vladivohaken)

Perf Gauge

Over here most people I know use the Stanley Gibbons "Instanta" perf gauge which measures to one decimal point, is easy to use, accurate and stable - and costs about $6. Some of the prices being bandied around on here seem rather excessive.

John W.

Image

Posted Sep 22, 17 6:06 by Ken Lawrence (kenlawrence)

Two cents' worth?

Dave,

An unsealed 1916 Christmas greeting?

Posted Sep 22, 17 6:04 by Ken Lawrence (kenlawrence)

GPS BSG perforation gauge

Glenn,

It's the gauge pictured actual size at the right on the instruction sheet. It's not the one you described; it doesn't have Kiusalas dots, only the long continuous scale. It's the world's most accurate stamp perforation gauge, out of print for about 20 years and can't/won't be published again.

Posted Sep 21, 17 19:49 by Dave Savadge (nomad55)

Two cents to Switzerland??

This 5 December 1916 cover shows no indication of postage due, nor is there any indication of a stamp that had fallen off. The reverse only contains a Speicher receiving mark dated 28 December 1916.

The 23 day transit makes sense, due to the war. But why two cents postage? Switzerland did not come under the two-cent direct steamer treaty rate to Germany, which had been suspended.

Anyone have suggestions?

Image

Posted Sep 21, 17 18:58 by Glenn Archer (archerg)

Perf gauge - Thanks for follow-up

Many thanks for looking Ken - If it's the same gauge I know it's the best I have used, though I am recovering from sticker shock at the moment. If you have a picture of it, I'll know if it is the same. The Board might expense it, can't hurt to ask.

I know many Canada Small Queen collectors who still use the Kiusalas gauge, I think they would get bought up with little trouble.

Posted Sep 21, 17 16:30 by Ken Lawrence (kenlawrence)

One dozen GPS BSG Gauges FS

Glenn Archer jogged my dusty memory. Bill Weiss ordered the last 12 gauges, then got into a snit about something else and never sent his check. I found them still in the file. $950 postpaid to a U.S. address for the lot; foreign postage extra.

Posted Sep 21, 17 14:07 by Richard Drews (bear427)

Perf Gauges

Some 20 years ago I bought the remaining supply of Kiusalis gauges. I quickly sold out of the few hundred U. S. gauges. I never got around to marketing the box of Canadian gauges. I bumped into them a couple of years ago. If somone wants a large quantity I could probably locate them.

Rich

Posted Sep 21, 17 13:32 by Gregory Shoults (coilcollector)

COIL STAMPS

Ken, thank you for the suggestions. I will look for a full pane of 100 with numbers on the two sides. I would really like to find an example of 410 or 411 that has been miscut to show the partial plate number on the vertical edge.

Posted Sep 21, 17 13:30 by Ken Lawrence (kenlawrence)

Gauge

The GPS BSG gauge is longer than Instanta, much longer than the Instanta scale. Besides the shorter length, Instanta plastic suffers from cold flow (the scale shrinks).

Posted Sep 21, 17 12:54 by Glenn Archer (archerg)

Perforation gauge

Thanks for posting that image - it is similar. Has the Kiusalas perf measurements as well on the gauge, is quite thin and flexible clear plastic, and is physically longer than the Instantas. My old Instanta is so scratched after 40 years of use that I prefer not to use it.

I could cite many examples where a difference of 0.2 perfs is significant. We held our monthly expertizing meeting yesterday and had a debate about a submission. The stamp in question was submitted as a #13 (perforated 6d, perfs close to 11 3/4 all sides though I find it will vary a bit). I suspected it originally a #5 with perforations added long ago to appear as a #13, then was reperforated a second time at left. My measurements of 11.9 - 12.1 all four sides (and all four sides were different!) convince me I am right - but a colleague measured 11.75 all around, which gave us cause to seek an electronic perf measurement as an independent opinion.

There are a number of sources of error associated with manual perf measurement - alignment of the gauge, parallax, the perf holes themselves must be considered as the pins were not always straight - but if we had a standard gauge we could be more precise, and perhaps achieve agreement within say 0.2 perfs per 2 cm.

Posted Sep 21, 17 12:09 by Ken Lawrence (kenlawrence)

Gauge

David H,

Yes, if you read Julian Goldberg's articles on Canadian and United States perforations you'll see that accurate measurements to the tenth and hundredth gauge do make a difference to specialists. They also make a difference in authenticating scarce and rare perforation varieties.

Posted Sep 21, 17 12:06 by Ken Lawrence (kenlawrence)

GPS perforation gauge

The gauge you probably mean was published by the Buildings Study Group of the Germany Philatelic Society on dimensionally stable lithographic film back in the 1980s. At the time I was a member of the Bureau Issues Association committee that hoped to manufacture a gauge that would replace the United States Expert Gauge published by Richard Kiusalas in the 1960s. When the GPS BSG published its gauge (the local club at Eastman Kodak Company actually created it), the BIA adopted it, as committee chair Bob Kitson reported in the United States Specialist. The first edition of the gauge sold out. I bought all the remainders of the second edition, which I included among the materials provided to students who enrolled in my seminars on philatelic expertizing. In 2012 I found a handful in my file that I sold two for $150 (no one wants just one; the scale is printed on the side that you place on the stamp to eliminate parallax, but that means they can easily be scratched).

Note: The scan makes it appear that the diverging lines are stepped. They are actually straight.

Image

Posted Sep 21, 17 11:56 by Richard Frajola (frajola)

PDR 2017 Update

I would like to welcome Eric Glohr who contributed the newest single frame exhibit to PDR. Thank You!

1847-1848: A Transitional Period for Michigan's Capital City

Posted Sep 21, 17 11:38 by David Handelman (davidh)

perforations

Can you give an example wherein a few percent tolerance would make a difference in the expertization? For example, if a large queen has a perforation between 11.9 and 12.1, would a more accurate measurement really make a difference?

Since the paper itself changes in size with age (depending on how it is stored, or whether on cover), and in addition, perforation measurements can be changed (slightly) by soaking and then drying, it seems pointless to require precision in measurement.

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