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Looking at old and new prints with an USB microscope is revealing and with some experience can lead to their identification. Printmaking history is fascinating as well as a complex subject. I like to share in this post some basic hints on their identification using the USB microscope but heartily recommending further readings [1, 2], since the number of techniques and variations is extraordinary, so a definitive attribution deserve an advanced knowledge. Though, even if the subject is complex, this doesn’t mean we cannot have some good time, experimenting a bit with prints. A great online resource is the IPI (Image Permanence Institute) Graphics Atlas [3].
Pre-photographic printing methods are classified in three main categories: Relief, Intaglio and Planographic. This post covers the first two.
Relief Printing
This is the oldest of the printing techniques. On the relief block – wood or metal – the non-printing areas are cut away and the ink is applied to the remaining raised areas by dabbing or with a roller. Then the ink is transferred by laying a sheet of paper and applying pressure.
Relief is identified by:
- Edges’s rim. The process of transferring the ink from the block applying pressure produces a characteristic rim on the edges of the printed lines. This is a sign characterizing only relief printing.
- Embossing. Relief printing can show embossing on the back of the paper caused by the pressure applied. RTI (Reflectance Transformation Imaging) is the most suited photographic method to document embossing).
Intaglio
Intaglio means incising in Italian and this technique was developed in the 1500s. On the contrary to relief, the ink is held in grooves on the block’s surface.
Intaglio is identified by:
- Varying ink intensity. The main characteristic of this technique is to show lines with varying ink intensity while in relief the intensity of the ink is always the same. Since the grooves’ depth can be adjusted, the ink collected in it would vary and this translates in darker or paler printed lines.
- Raised ink. In strong dark lines the ink considerably rises up from the paper.
Intaglio by Engraving
There are two techniques to cut the lines of an intaglio print, engraving and etching. Engraving is the oldest method and it uses a burin with sharp V-shaped cutting section, which is pressed gradually down onto the surface of a copper plate and then driven more or less deeply through the metal. It will be raised up at the end of the line to lift out a sliver of copper.
Intaglio by engraving is identified by:
- Shape of the line. It has clean edges, tends to be pointed at each end and to swell or diminish during its length. The controlled act of engraving also gives the line a formal character.
Intaglio by Etching
In the etching techniques the cutting is done by an acid and the artist can draw freely on the wax covered copper plate.
Intaglio by etching) is identified by:
- Shape of the line. Etching uses a rounded needle that passing through the wax ground give a more blunt end to the line than the engraving tool. And the very slight crumbling of the wax to either side of the line, combined with the somewhat uneven action of the acid, results in the less precise edge to the line than in an engraving. Etched line will be of the same width along their length, while the burin gives swelling shapes.
References
[1] B. Gascoigne “How to identify prints” Thames and Hudson, 2011.
[2] A. Griffiths “Prints and Printmaking” British Museum Press; 2nd Revised edition, 1996
Hello again, Antonio.
We carry out frequent examination of documents, including analysis of indented writing. We’ve tried RTI, but in most cases ESDA is better, and considerably faster. The time taken to set up, capture, and process an RTI image of a document can run into many tens of minutes, and that’s assuming the capture is successful first time. An ESDA machine can reveal indented wiriting in under five minutes!
For occasional use, and where ESDA equipment is unavailable, RTI is fine. But, any lab which wishes to reveal indented writing on a regular basis, I strongly recomment an ESDA system. They are not expensive.
Best wishes,
John Anderson.
John, thank you, I didn’t know about ESDA. I found some material on wikipedia and the website of the manufacturer.
http://www.fosterfreeman.com/
I have several stamps (same stamp) that I believe a small part of which did not receive sufficient pressure to cut lines into the soft metal (before hardening) from the master design.
The Royal Philatelic Society London – state ”Has been caused by a dry print or by fading since the time of the issue”. I have studied and printed Intaglio and disagree with their findings. Is their a Body that Intaglio printers belong to that I might have my stamps looked at for a second opinion??
Or any accredited person that might help examine these stamps please? Thank you
Hi Anthony, sorry I can’t help you on this. 🙁 Hope somebody reading this can find a solution for you