Difference Between "Intaglio" & "Photogravure" Printings

I was referred to this thread regarding a new thread I just posted. Rather than re-post please take a look. I'm now really confused after reading this thread.
Austria Scott 481 or 499 (screen or no screen)
http://goscf.com/t/52843#459596

Thanks for any replies.

Glenn,

could not find your thread!

Rein

Rein, Sorry, but the thread removal is the fault of Stamp Magazine. GLENN

As to the 1917 onwards Mexican stamps in unscreened photogravure, it is now clear they have been printed on Waite&Saville die stamp presses reel-fed [!]! I will get to this subject later on.....

More bout the Mexican stamps!

http://goscf.com/t/37209

Monograph
Maasi Mara University
Broad Overview of printing for those of interest.

SCHOOL OF SCIENCE AND INFORMATION SCIENCE
TOPIC: TYPES OF ANALOG PRINTING METHODS AND TECHNIQUES
(Academia)
https://www.academia.edu/18418551/A...TING_METHODS
Including
CHROMOXYLOGRAPHY
GLYPHOGRAPHY

In MSWord I had to convert to PDF

This is a great thread, however, most of the links / images posted to it have disappeared. I am writing to ask that the original authors attempt to re-add their images if possible.

What I'm ultimately trying to find out is a side-by-side comparison of stamps printed with lithography and gravure. I'm getting stuck trying to determine the difference between two same value, same color stamps differentiated by how they were printed. This comes up with Machins and is driving me bonkers.

BobinRye,
The vast majority of missing images in this thread came from Galeoptix and his website. Unfortunately, Galeoptix has passed and his website has gone dark. (The images were not archived.) This is why we encourage folks to upload images to the SCF instead of linking to other sites.

Perhaps one of the other SCF members downloaded and saved Galeoptix's images?
Don

All the above pictures are reachable, just not rendered in the forum. If you right click and open in new tab you can see them.

Ah, I see the issue. Galeoptix's original forum is still online but is marked as 'not secure' and therefore the image links in his posts do not work. If I find the time, I will download them all to my PC and then upload them back into his original posts.
Don

Not a Machin specialist.
Is it not an easy ID ? I have always thought the Photogravure stamps, can be identified by the "pitted" lines of the image (esp the value tablet) under a loupe.

This does not happen with Lithography, the edges of the vale tablets are clear and straight.

I'll dig out an image if I can, once mastered it is quite easy, but you'll need a good loupe, magnifying glass

I can print out the Photogravure process, for you, but it would likely confuse, rather than enlighten.

Tip: Get your loupe, and focus on the value figure, look at the edges
of the value. a pitted or irregular edge will be photogravure.

Thanks, Rod. Clearly visible at the frame of the image. As you suggest, the frame is "pitted" (I'd say speckled, but the same thing) for gravure. For litho, it's very smooth / straight. That solves a big question for me. I've spent days sorting through my SG album to try to figure out which stamp is which!

Great !




Knowledge is never just blessed on anyone, without prior work.

I spent some time scratching my head over these in the past also

Correct:




The picture of the screened border shows something that occurs with photogravure printing, but is not something you find on all stamps.

Photogravure is made up from little puts that hold the ink. This gives a dotted image. As the Machins are printed on rotary presses, the ink flows against the movement of the paper through the press. So, if the image is printed from the bottom to the top (Direction Of Printing - DOP - is upright ), you will see the dots of ink take on the shape of a droplet that point upwards.

Often, you can see the droplets anywhere in the printed area. The portrait tends to be a good part of the image where you can see the droplets. Where the printed area meets an unprinted area, along the edge of the image, you can see it best. Also, that is the area where it is easiest to see the direction of the droplets. It gives a jagged edge.

Here is a very clear example and a discussion on the DOP:

http://goscf.com/t/79543

Lithography is etched in another way and has sharp borders. Lithography stamps were not made up from dots and you won't see the sawtooth edge. New techniques do result in a 'dotted' appearance of litho-printed stamps.

There are caveats:
Bad litho printing can lead to fuzzy edges and excess ink can fill up the border of a gravure stamp.
Later gravure printings (photogravure was replaced by computer-aided engraving) are of better quality and have a higher 'screen.' At the same time, litho printings have been made with stochastic screens. Galeoptix has posted about this.
It does not always work:
here is an example of a Dutch stamp printed in photogravure by Enschedé that has a sharp outline. This was done on purpose.

http://goscf.com/t/80894#747172

And here is a thread showing the stochastic screen of a litho printing (Hong Kong Machin):

http://goscf.com/t/76488

NSK - thanks for your excellent images. Luckily for me, I'm focused on Machins from the 1990s.