Perforations To Millimeters

I have recently completed a topical collection of worldwide stamps depicting WWII resistance people and events. The Scott catalogue gives me perforations but mounts are apparently sized in millimeters. I was wondering if there was a way to convert perforations to mms other than measuring each stamp or set?

'Perforations' (perforation gauge) is the number of perforations per 2 cm = 20 mm.

This has nothing to do with the size of the mounts.

I realize that and have all that information for all the stamps, but want to convert the perforation numbers to millimeters., if possible without measuring each stamp/set

You measure the perforation gauge, you should not count perforations. The slightest rounding or mismeasurement will give incorrect numbers.

There are several perforation gauges on the market. You can use those to measure the perforation.





Not possible. Perf. is a number of perforations per given number of mm. You cannot convert a perforation gauge to mms as the number always refers to 20 mms.

A stamp perf. 12 that is 2 cms wide has 12 perforations. One that is 3 cms wide has 18. Both are perf. 12. If the gauge is rounded to the nearest half, it can be (almost) one more or less.

It is possible to establish the stamp size in mm from the perforation count given in the catalogues.

As NSK pointed out, the count given in the catalogues is the number of perforations over
20mm, so all you need do is count the perforations along the edge of a stamp, divide this by the number given in the catalogue and multiply by 20.

e.g if a stamp is listed as perf 14 and you count 19 perforations along the edge.
length=(EdgeCount / CatPerfs) x 20
length = (19 / 14) x 20 = 27mm

I think that it might just be easier, and more accurate, to use a ruler :)

Clive

Once you get used to mounts you will be able to eyeball the stamp and what it needs. Probably 80% of stamps use 26 mm, vertical commemoratives use 39.

As I recall, some mount manufacturers actually provide the correct mount sizes for stamps issued during recent years ... at least, this was true for U.S. stamps. You might check the web site for whoever makes your mounts.
Added: Just noticed you said "worldwide". So my suggestion may not be helpful.

It's much cheaper to buy mounts in strips, rather than individually cut. I don't know about the US, but here vendors will typically have a range of strip heights at the same price, so buying the largest gives the widest coverage.

Here's an example

https://www.britishstamps.co.uk/haw...-strips.html

That is highly inaccurate. You might want to add one or two mms to be sure the mount is not too low. But if you have the stamp to count its perforations, why not measure it?

Keep in mind that perf gauge for a stamp is a relative measure, and stamp size is an absolute measure. It would be like trying to convert 60 miles per hour into 60 miles. The 2 measures are unrelated.

Some foreign catalogs may have stamp size information, but by the time you looked this info up you could just as easily have measured your stamps.

And if they have stamp size information, you need to know if it is the size of the stamp or of the image like Fesofi. This may be utterly useless when the perforator does not move at constant intervals.

Let me cut through the noise and be blunt. Perforation gauge numbers are the number of holes in a set space with out regard to the paper perforated. Furthermore the count of the number of perforations (gauge) is about +/- 5%.

Stamp size has zero relation ship to the perforation gauge. It will then be much easier to use a ruler to measure the stamp that using the ruler to get the precise and fractional number of perforation to then count the perforations to determine the stamp size. And how do you determine size when the stamps are not perforated when issued? You get that ruler and measure them.

THE GOOD NEW IS: Stamps, by country tend to fall into a certain number of sizes, just a handful normally. Thus it is a quick learning curve to know what size mount to use. For example for US stamps there are pre-cut mounts for certain sized stamps such as regular issue, commemorative, champion of liberty, large or small.

What are you mounting your stamps into?

If it's a modern commercial album or even Steiner pages, there is a printed frame around each stamp and the mount should be the same size as the frame line, unless you are leaving space for selvage or a plate#, and it results in a nice roomy border.

Also, if you are using split back mounts, being too fussy about matching the stamp size can result in crushed perforations, and gum disturbances on never hinged stamps.

Personally I prefer top loaders and find my pocket metal mm ruler the simplest-to-use tool.

If you're freewheeling it into an exhibit, or something similar, cut them with 2-5mm of breathing room all around.

...just my 2 Pesetas.

Al

Beware that if you use Steiner pages, the frames are not always the correct size. I lay the stamps out on the pages first to see if the frames are close enough. This is a visual check, looking for uniform space on all sides. In my opinion, the ideal is 2mm each side. For example, a 25mm high stamp that is 22mm wide should have a frame that is 29x26. You will quickly get used to eyeballing what looks good or close enough. For the mount, I use the height of the stamp to pick mount size (25mm high stamp gets mount size 25mm which is actually 30mm high mount) and cut to the width that matches the frame, not the stamp. Sometimes the frames aren't perfect, too narrow or too wide, too short or too tall, but I don't have time to correct them. I will redo pages if frames are more than 1 mm too tall for the mount being used, more than 3mm too short, or more than 2mm too narrow. I've had to redo hundreds of frames. Just recently I laid out Cuba 1941-1959. There are a handful of frames that must be redone. Sadly this is a cost because I have to reprint the page. It's not reasonable to check frames before printing.

Buy mounts in the sizes you think you will need. You can use a mount-size gauge to measure them. These are very cheap to buy.

When you want to put a stamp into a mount, just use the mount-size gauge to determine its approximate size then put it into that mount. If it won't fit, try the next size.

This has nothing at all to do with perforations. Buy a cheap mount-sizing gauge and you're all set. All sellers of stamp mounts have these for sale -- or on ebay.