Home > The Catalogue > Introduction




The project records and checks the data on impressions in major collections as fully as possible.
Etchings have been examined by the Project team under varying conditions - in print rooms, conservation laboratories, private homes, salerooms, in cupboards and on walls, with daylight and other variable lighting. When possible the paper has been backlit or placed in a light box to check the type and look for watermarks. However, some impressions are tipped down, laid down on card, mounted or framed, so that it is impossible to examine the paper properly, or see the margins or verso. Thus it is impossible to record precisely the same data on each impression.
The entries on individual impressions record when the information that has been checked by the Project team, or derives from museum or other records.


All measurements are given in both millimetres, with height preceding width. When the copper plate exists, then the size of the plate is given in millimetres, with height preceding width.
In addition, the plate mark (the indent made by the plate during printing) is measured from the outside of the mark. Three vertical measurements have been taken, at each side and centre, and three horizontal measurements, at top, centre and bottom. The largest measurement is the one given in the catalogue.
When the plate no longer exists, then the size of the plate is calculated. The measurements of individual impressions of any one etching may vary by a considerable amount, depending on the paper and pressure of the press. An average size is calculated from etchings measured and checked by the Project team.
The size of the paper is also measured wherever possible, using the same method. The vertical measurement of the paper includes, where relevant, the tab left by Whistler for his signature. If there is 5mm or more difference between measurements than it is given as, for instance, 5-11 x 8 mm.
Western papers are classified as laid and wove. Watermarks and distinctive features of the paper have been noted where possible. Asian papers have been classified as such, with distinctive characteristics noted where possible, but the full range of such papers is not recorded. Such data is only available through specialist conservation reports in some major public collections; we are undertaking further research on this
Paper colour is usually given as white, ivory, cream, buff and tan (there are a few exceptions, such as blue or grey paper). Lighting conditions can make this a rather subjective process. Colour is therefore to be considered an approximation, and should be considered in association with other aspects of the physical description of the paper.
Impression: K1970103
San Biagio [237], printed in black ink on buff laid paper.
Impression: K1970702
San Biagio [237], printed in dark brown ink on ivory laid paper.
Inks are described as brown, dark brown and black. There are an infinite number of shades of ink, and the inks appear different under different lights and on different colour paper. However, the cumulative data on ink colour suggests that this is helpful and helps to compare and date impressions. For instance, Whistler usually printed working proofs in black ink, even if later impressions were in shades of brown.