New light on old seals

In her first blog post on the wonders of Polynomial Textual Mapping (PTM) Dinah Eastop used a modern embossed paper seal as an example of the way in which this new technology can literally highlight and capture virtually invisible details on the surface of three-dimensional objects. So what about earlier wax impressions of seals – would PTM help here?

The National Archives holds probably the largest collection of seals in the country. Seals were used in the medieval and early modern period to authenticate documents as well as literally to seal them. They can include portraits of the owner, coats of arms, depictions of animals or buildings and much more, and most also include writing around the circumference (called the legend) identifying the owner. Many of the seals in The National Archives’ collection are fragile, many are small, and some are damaged, and it can sometimes be very hard to see what the seal depicts.

Traditional photography has often struggled to represent seals adequately, because of the need for light and shade to capture the detail on such small and intricate objects. This is especially true for seals depicting heraldry where even a very small difference on one coat of arms might distinguish it (and the seal owner) from another.

Seals also provide invaluable evidence for the origins of heraldry. In a seminal article published in 1894 the eminent (if occasionally spiky) historian and genealogist, J. H. Round, demonstrated that arms were first introduced into England in the 1130s and 40s. He based his argument on the arms of the great Clare family believing ‘the key to the whole problem’ lay ‘among the Duchy of Lancaster charters, preserved in the Public Record Office’ 1 now The National Archives, namely the seal of Gilbert Earl of Hertford DL 27/47 dating to the 1140s. 2 Round was fortunate. The heraldic chevrons (upside down Vs) of the Clare coat of arms are just about discernable on the earl’s shield depicted in strict profile on his seal. They are however, much more visible using PTM (obviously not available to our great Victorian scholar) and one wonders just how many more early coats of arms await to be discovered and permanently recorded using this new technology. Scholars of dress, armour, architecture, weapons, ships, saints and a host of other favourite seal devices apart from heraldry may well benefit from PTM.

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[rti src=”wp-content/uploads/2013/06/DL27_47_cropped_545.ptm” width=”545″ height=”536″]

DL 27/47: The seal of Gilbert Earl of Hertford, dating to the 1140s.

Download the software

For the full experience, including the ability to zoom, you can download the RTI Viewer software, available from, then explore the original high-resolution files by right-clicking this link, saving the image to your desktop, and opening it in the RTI Viewer: seal of Gilbert Earl of Hertford (89Mb).

Further reading

Elizabeth A. New, Seals and Sealing Practices, British Records Association, 2010

SIGILLVM – Seals and Sealing: History, Art, Preservation

The National Archives’ research guide on seals


  1. 1. J. H. Round, ‘The Introduction of Armorial Bearings into England’, Archaeological Journal, vol. 51 (1894), pp. 43-48
  2. 2. Duchy of Lancaster material in The National Archives is reproduced by permission of the Chancellor and Council of the Duchy of Lancaster


  1. stephen layland says:

    Att’n: Adrian Ailes.

    I was ones of those able to attend the first part of your recent Workshop of Heraldry arranged by Bristol University’s Centre for Medieval Studies on Thursday 05 December 2013.

    Just prior to the change to the group(s) exercise part of the workshop, you projected a full screen image of a Coat of Arms, that had featured two lions as I seem to recall.

    I also recall that the end of the two part motto was “secret” or “in secret”.

    I was not alert enough to remember the name of the family or other body that owned that Coat of Arms.

    May I ask you to let me know the name of that family or body.



  2. John Rassweiler says:

    Adrian Ailes blog on PTM ( polynomial Textural Mapping) is most interesting. I purchased a
    digital scanner and had several matrices scanned. The results were interesting
    and showed promise, but while we picked the best available camera system for
    under $2500, we were not satisfied with the detail quality or the amount of
    time required to get a satisfactory scan. The supplier has been working with
    us to improve sensitivity of their system, but we are not optimistic.

    Here in the US, preliminary research suggests an investment in the $15,000+ range
    is needed to get the best sensitivity. While tolerable for the National Archives, a
    bit beyond my capability as the work is done by an unpaid volunteer, and the
    investment for 500 matrices probably unjustifiable.

    As you may remember, several years ago , Sandy Heslop and his daughter reported on their use of a
    very high-end PTM type device to produce good images, but it seemed agreed at
    the time, it probably was not practical yet for general use.

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