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Lithography, offset, offset/litho, photo/offset  
 

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Pillar Of The Community
Netherlands
640 Posts
Posted 02/18/2014   04:14 am  Show Profile Bookmark this reply Add Galeoptix to your friends list  Get a Link to this Reply
Criss cross i.e. haphazardly placed dots is what stochastic is about, there is NO system in it, everything is at random. The term stochastic comes the probability theory (mathematics).

The recent Australian, the Canadian issues and our Lowe-Martin all have the real stochastic screens.

The earlier Australian and the Danish still have the cross-type, horizontally/vertically place dots like in the offset-litho stamps in the 1950-ies and later.
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Pillar Of The Community
Netherlands
640 Posts
Posted 02/18/2014   04:19 am  Show Profile Bookmark this reply Add Galeoptix to your friends list  Get a Link to this Reply
The Sprintpak started using so-called stochastic screens years ago, but for years they were just fake - when having a closer look you could still see the diagonal patterns, only around 2005 they really switched to stochastics!

The real thing:

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Pillar Of The Community
Netherlands
640 Posts
Posted 02/18/2014   06:31 am  Show Profile Bookmark this reply Add Galeoptix to your friends list  Get a Link to this Reply
For the first time Lowe-Martin, Ottawa printed Dutch stamps is was the 100 years Patents Bureau, issued February 9, 2010.

What I wrote then - in 2010 - was that they had printed Canadian stamps since 2002 in offset-litho, mainly self-adhesives. To start with the Tulip Festival of May 3, 2002.

Furthermore they printed stamps for agencies representing outside-Europe "countries" but aos for real countries like Finland and Iceland.

In the case of the Dutch stamps of 2010, they were not self-adheisve but perforated normally. They did use stochastic screens called as Lowe-Martin said „10-micron stochastic screening". I could not tell whether they used offset-litho sheet-fed or reel-fed then. They could choose from a
Gallus reel-fed offset-litho press or a 10-colours sheet-fed Heidelberg CD offset-litho press, acquired in 2006.

When Joh.Enschedé stopped using their Goebel reel-fed photogravure press by the end of 2012, the Dutch Post Office was obliged to find another printer for the coil stamps. Strangely enough they did NOT contract the Belgian Zegelwerkplaats with whom JESP cooperated but gave the order to Lowe-Martin!

Dutch coil stamps are printed in Canada since then.
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Valued Member
United Kingdom
262 Posts
Posted 02/18/2014   06:40 am  Show Profile Bookmark this reply Add 65170 to your friends list  Get a Link to this Reply
For further stochastic screening information see my article at http://www.stampprinters.info/SPI_Stochastic.htm

GLENN
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Edited by 65170 - 02/18/2014 06:40 am
Pillar Of The Community
Netherlands
640 Posts
Posted 02/18/2014   06:53 am  Show Profile Bookmark this reply Add Galeoptix to your friends list  Get a Link to this Reply
The coil version - kiss die-cut - of this year:





The die-cut version:

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Pillar Of The Community
Netherlands
640 Posts
Posted 02/18/2014   06:56 am  Show Profile Bookmark this reply Add Galeoptix to your friends list  Get a Link to this Reply
Glenn,

do you not agree with me that in some cases the stochastic screen is NOT really a stochastic screen! Like in Australia at first and in Dania???

groetjes, Rein
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Pillar Of The Community
Netherlands
640 Posts
Posted 02/18/2014   07:05 am  Show Profile Bookmark this reply Add Galeoptix to your friends list  Get a Link to this Reply
Stochastic screens seemed to be an invention of the late 20th century... But the Russians at Goznak had their fototypia!





groetjes, Rein

P.s.

Phototypia was used for the first time in the State Printing House of Budapest for Bulgarian stamps in 1907...
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Pillar Of The Community
Netherlands
640 Posts
Posted 02/18/2014   07:10 am  Show Profile Bookmark this reply Add Galeoptix to your friends list  Get a Link to this Reply








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Pillar Of The Community
Canada
4373 Posts
Posted 02/25/2014   11:21 pm  Show Profile Bookmark this reply Add lithograving to your friends list  Get a Link to this Reply
Is this 2009 Austrian SS Scott 2210, offset/litho printing with real or fake stochastic screens ?


Printing by Österreichische Staatsdruckerei (Austrian State Printer)





The screening looks quite different from the Canadian printers,
whether Lowe-Martin or CBNC.
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Edited by lithograving - 03/24/2018 2:07 pm
Valued Member
United Kingdom
262 Posts
Posted 02/26/2014   02:44 am  Show Profile Bookmark this reply Add 65170 to your friends list  Get a Link to this Reply
Lithograving, the above stamp is not stochastic screening because it does not have a random dot formation, the main visible aspect of stochastic screening. (It also saves on ink usage, but that is not obvious on the printed piece.)

Instead, your item has a totally uniform appearance across the stamp sheet with rows of rosettes. As there appears to be no attempt at trying to hide the uniform appearance of the background pattern, to call it 'fake stochastic' would also be wrong and confusing to others.

To recap: Four-colour process printing cyan, magenta, yellow and black (CMYK) uses a combination of different size dots printing in an overlapping arrangement called a rosette. The combination of CMYK dots creates 'subtractive colour'*. To eliminate a Moiré pattern each row is angled off 30 degrees from each other with the yellow being angled 15 degrees off of the magenta or cyan angles.

Stochastic screening varies the pattern of dots rather than placing the dots in a straight row. Additionally each dot is the same size instead of changing the size of dot. The stochastic dots create shades of colour by increasing or decreasing the number of dots. Highlights will have fewer dots than the mid-tone or shadow areas. An advantage of this system is that images have a smoother or continuous tone appearance. Your sheet does not.

* 'Subtractive colour' describes the way that certain pigments mix, such as the result obtained when yellow+cyan overlap, creating a new colour without an additional(fifth) colour ink having been used.

Hope that clarifies matters.

GLENN
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Edited by 65170 - 02/26/2014 02:47 am
Valued Member
United Kingdom
262 Posts
Posted 02/26/2014   04:42 am  Show Profile Bookmark this reply Add 65170 to your friends list  Get a Link to this Reply
A picture always helps, so see below.



Stochastic screening is on the left, standard screening on the right.

The image is not taken from a postage stamp, but is cropped from a forum for the printing industry (apologies for not recalling which one).

GLENN

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Pillar Of The Community
Australia
3547 Posts
Posted 02/26/2014   08:20 am  Show Profile Bookmark this reply Add tonymacg to your friends list  Get a Link to this Reply
The Indian Security Printing Press at Nasik made great use of offset-litho from the late 1920s, for Jaipur



(SG 57 - 2 Rupees POSTAGE & REVENUE of 1932)

and Soruth



(SG 52 - the 2 Annas black and dull orange of the 1929 definitive set)

as well as for the Indian Post Office




(1935 George V Silver Jubilee set, with additional 8 Anna)
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Pillar Of The Community
Canada
4373 Posts
Posted 02/26/2014   12:31 pm  Show Profile Bookmark this reply Add lithograving to your friends list  Get a Link to this Reply

Quote:
Hope that clarifies matters.


Thanks Glenn, it's clear as mud. Just kidding.

I'm slowly beginning to understand what is meant by stochastic screening.

Your pic was most helpful.

So a uniform rows of rosettes = normal offset/litho.

Random dot formation = Stochastic screening

Was this stochastic screening achieved by the printers
using a new process with the existing (older) printing presses
or where new presses required ?
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Pillar Of The Community
Canada
4373 Posts
Posted 02/26/2014   3:57 pm  Show Profile Bookmark this reply Add lithograving to your friends list  Get a Link to this Reply
Glenn

I noticed that on your site the page http://www.stampprinters.info/SPI_Stochastic.htm about Stochastic Screening
mentions only that Sprintpak and Canadian Printers (Lowe-Martin & CBNC)

Do you know of any other printers as of now using this process?


I wonder if Ashton Potter USA uses this new superior print
technique ?

Since I don't have any recent US stamps in my possession are there
any Americans out there interested in this stuff who would show
us some sharp scans so we could discuss this ?

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Pillar Of The Community
Canada
4373 Posts
Posted 02/26/2014   4:04 pm  Show Profile Bookmark this reply Add lithograving to your friends list  Get a Link to this Reply
Tony, I love those bi-coloured KGV Silver Jubilees.

That type of offset printing was basically in those days state of the art.
They didn't have the high quality of engraved stamps but were much better than typography.

Just compare that to some of the stuff the Indian Post issues now.
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