Identify Prints. Relief, Intaglio, Engraving and Etching

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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].

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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.
How to Identify Prints. Relief, Intaglio, Engraving and Etching. Technical photography for prints and stamps.

Two US dollars bill, front side. The bright green of the serial number shows ink rim on the edges, characteristic of 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).
How to Identify Prints. Relief, Intaglio, Engraving and Etching. Technical photography for prints and stamps.

RTI (Reflectance Transformation Imaging) allows to document embossing better than raking light. “Il Capitano Spaventa”, R. Bemporad e Figlio editori, Firenze, 1924.




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.
How to Identify Prints. Relief, Intaglio, Engraving and Etching. Technical photography for prints and stamps.

Two US dollars bill, reverse side. The intaglio technique is evident in A) the raised ink in the strongest dark lines. B) dark lines accompanied by pale lines. The intaglio by engraving is evident in C) lines are pointed and diminish during their length.



[1] B. Gascoigne “How to identify prints” Thames and Hudson, 2011.

[2] A. Griffiths “Prints and Printmaking” British Museum Press; 2nd Revised edition, 1996


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  1. John Anderson April 25, 2013 at 5:07 pm - Reply

    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.

    • Antonino Cosentino April 25, 2013 at 11:13 pm - Reply

      John, thank you, I didn’t know about ESDA. I found some material on wikipedia and the website of the manufacturer.

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