Photo Documentation


Front cover: before treatment


Back cover: before treatment


Spine and front cover: before treatment


Front endleaves: before treatment


Opening characteristic: before treatment


Front cover: after treatment


Back cover: after treatment


Spine and front cover: after treatment


Front endleaves: after treatment


Opening characteristic: after treatment

Treatment Record Documentation

Date of Examination:  July 14, 2017

Title:  Encyclopedia

Author: Denis Diderot (1713–1784)

Date: 1771

Owner: Rare Book and Special Collection Division, Library of Congress

Call Number: Folio. AE25 .E56 V.3 Copy 1 Rare Books


Background Information:

The book is volume 3 of text of Diderot's "Encyclopedie".

The LC set of Diderot encyclopedias was bound by Robert Aitken, well known Philadelphia printer and binder. His ticket is affixed to the upper left corner on the pastedown. There is also a bookplate from Gouverneur Morris, who was a member of the Continental Congress as well as a signatory for the Articles of Confederacy and author of portions of the Constitution. There are two Library of Congress bookplates above Morris's.

In addition to the distinctive provenance, the LC set of Diderot is heavily used on a consistent basis. The complete set is regularly incorporated into the Rare Book School class taught here at LC as an exemplar of 18th century printing.




Binding:  The binding is full, reddish brown, tree calf sewn on recessed cords. The overall appearance of the binding is French 18th century style, with the spine and joint leather pared thin. The spine has extensive tooling in gold and blind. The design creates nine panels with the following tooling motifs: the top panel has a grecian urn stamp in gold in the center of the panel, with decorative borders. The second panel from the top has the title tooled in gold on a red calf onlay label, read “ENCYCLOPED OU DICTIONAIRR DES SCIENCES”. The third panel has a repeating shell motif in gold. The four panel has another red calf onlay with the volume number (III.) tooled in gold inside an oval with a decorative border. The remaining panels (panel five, six and eight) all have the grecian urn motif. There is a small panel between the panel six and eight from the top with a label fragment, and two decorative horizontal lines at the tail. Based on other bindings in the set and the underlying type impression, the label fragment originally had an onlay with the word "CH=CONS" tooled in gold. Both the upper and lower board have a thin gold decorative border at the edge. The endsheets are marbled paper, with what appears to be a French pattern. The pastedowns have Robert Aitken's binding ticket on the upper left corner (Bound by R. Aitken at Pope's head, Philadelphia), an LC Rare Book collection bookplate, another LC bookplate with shelf mark, and the plate of Gouvernour Morris.

There are red and green end band threads left in the text block though no other traces of the endbands remain. There are five distinctive cords under the pastedown.

A blue silk ribbon bookmark had originally been adhered in between page 420 and 421, which is suggested by the ribbon residue at the head. But the ribbon was now broken from the head and the major part of the ribbon have been reinserted between page 208 and 209.

Text-block: The text-block is printed on handmade, medium weight laid paper in off-white color. There are a variety of watermarks and countermarks visible, including “A M F” (title page), unknown (iij), unknown (page 4).

The printer's ink is a rich brown black that provides a striking contrast to the support pages. The edges of the book block are stained yellow, though it appears in some areas that it was originally more green in color. There are pencil annotations on the back of title page.




Binding: The binding is in fair condition overall. The sewing is robust and intact. Other elements of the binding, however, are failing due to prolonged use and the chemical instability of the materials. The spine leather, while largely still intact, is brittle and cracking from preferential openings. The leather over the joints is missing completely and both boards are fully detached. The head and tail caps are missing. The board edges are exposed due to loss and abrasion of the leather. The exposed board is soft, pulpy and bumped at the corners. The endpapers bifolios are broken along the spine edge.

Text-block: The text-block is in good condition. The support paper is chemically stable and remains flexible and strong. There is a small tear on top of the last page (page 852). There is moderate foxing throughout the text-block.



1. Face the spine with a light weight, solvent set tissue and lift off the book mechanically. Retain.

2. If possible, thin down the spine leather and reattach to the re-backed volume.


1. Consolidate the deteriorated areas of leather with 2% Klucel G in ethanol, applied by brush.

2. Consolidate the delaminated board corners with wheat starch paste.

3. Fill losses in the board leather with toned leather.

4. Mechanically lift the leather on the spine edge of the boards.

5. Lift the pastedowns at the board edge in order to insert the turn-ins and the airplane cotton flange.



1. Repair the torn edge inside the text block with kozo paper.


1. Dry clean end sheets and mend tears with kozo paper and WSP.

2. Hinge fly leaves to the spine with thick stubs of kozo paper.



1. Clean the backs of the sections using a series of poultices.

2. Line the spine with a medium weight long-fibered paper.

3. Adhere an aero-linen spine lining. The lining will extend past the shoulders and act as a board attachment.

4. Sew through the linen spine lining to reinforce attachment.

5. Sew new end bands off the book and adhere to the spine. The thread will match the original thread and the thread from previously re-backed volumes as closely as possible.

6. Adhere a 1-on, 2-off hollow tube made from western machine made paper.



1. Prepare new spine leather. Color of leather will be adjusted with BASF leather dyes.

2. Adhere the linen flanges to the inside of the boards under the lifted paste downs with WSP.

3. Re-back with pared calf leather.

4. Re-adhere the original, lifted leather.

5. Re-adhere the lifted paste downs.

6. Repair the breaks to the folds of the endsheets with long-fibered paper printed with the marbled pattern. The paper will be printed with pigmented inks for permanence of color.



1. Rehouse the volume in a CMI box.

Risks of treatment:

Despite facing the leather prior to lifting, it is likely that some portion of the original spine will be lost. This potential outcome is due to several factors. The spine leather is pared extremely thin, which is consistent with the French style from the second half of the 18th century. The difficulty of removing a thin spine is compounded by the amount of tooling. In many places, significant pressure was used to make the impression, leaving the leather underneath thinner and more stressed than in surrounding areas. Finally, though the volume does not have a significant round, the shape, particularly near the joints, will create challenges.

Moisture will need to be introduced during two steps of the treatment. Older calf skin, like the leather found on the Diderot bindings, is notorious for darkening when exposed to humidity. It is possible that the adhesives used to face the leather prior to lifting and to re-adhere the leather when it is put back down or returned to the book will cause it to darken.

Justification for treatment:

The Diderot set is a high use item for RBSCD. It is significant for its provenance, its association with Aitken, and its importance in the history of printing and illustrating. During Rare Book School in June of 2015 the entire set was utilized. In anticipation of continued use, the division has had it on their annual call list for the past 2 years. The risks posed to the set by treatment can be mitigated through careful work. Additionally, the risks to the set from having detached boards is also significant. The benefits of treatment to the entire run far out-weigh any risks associated with re-backing.



1. Deteriorated leather was consolidated with 2% Klucel G in ethanol, applied by brush.

2. The spine leather was faced with three separate strips of RK-0 tissue pre-coated with acrylic resin adhesive (1:1:3 Avanse MV-100 : Plextol B500 : DI water). The adhesive was reactivated with ethanol and the tissue applied to the spine with a stiff brush.

3. The spine leather was lifted mechanically with lifting knife.


1. Deteriorated leather was consolidated with 2% Klucel G in ethanol, applied by brush.

2. Delaminated and worn away board corners were rebuilt with blotter, cord fibre and WSP (Aytex P precipitated wheat starch paste).

3. Missing leather on the board corners was filled with the same leather used in the re-backing and applied with Lascaux 498HV.

4. Leather on spine edge of the boards was lifted mechanically with scalpels and lifting knives.

5. Losses at the spine edge of the board leather were filled with blotter and WSP.


1. The end sheets were dry cleaned with Staedtler Mars Plastic erasers and eraser crumbs.

2. In the course of treatment, the upper Library of Congress bookmark from the front board became partially detached. It was reattached with WSP.

3. Tears were mended with kozo paper (RK-0 and Fides, 1203) and WSP.

4. Losses were filled with kozo paper (Hiromi, Senka-shi Thin, HM-35) toned with colored pencils, and with digitally reproduced and printed replica endpaper (Hiromi, Senka-shi Thin, HM-35) adhered with WSP.

5. Fly leaves were hinged to the spine with stubs of kozo paper (University of Iowa Center for the Book kozo toned with Golden acrylics) and WSP.

6. Pastedowns were mechanically lifted at the board edge.


1. The spine was cleaned mechanically and with a series of methyl cellulose poultices.

2. The spine was lined with long fiber kozo paper and WSP.

3. An overhanging, bias cut aerolinen lining was adhered to the spine with PVAc and wheat starch paste (1:1 PVAc: WSP).

4. Two gatherings a centimeter in from the front and back of the book were sewn through the linen spine lining (25/3 linen thread)

5. New endbands were sewed off the spine on a core of hemp cord stiffened with PVAc wrapped with aerocotton. Endbands were sewn using buttonhole silk thread (Bookmakers, 8wt) with a single bead on the front in the colors that were the closest match to the endbands sewn by David Brock on volume 1 of the set in 1986. Colors are 064 Claret and 099, a dark, forest green.

6. The endbands were adhered to spine with PVAc and WSP.

7. The spine was lined with Griffen Mills Early Wove Cream handmade paper and wheat starch paste. After the paper lining was fully dry, the paper lining was slightly sanded with a piece of sandpaper to improve the smoothness of the spine.

8. A hollow tube was constructed from western handmade paper (Griffen Mill Early Wove Cream), sized with PVAc on the outer side of the paper.

9. The tube was adhered to the spine, 1-on, 2-off with PVAc.


1. New calf leather was dyed with BASF leather dyes diluted with isopropanol. The leather was pared.

2. The linen flanges were adhered to the inside of the boards under the lifted paste downs with 1:1 mix of PVAc and WSP. The lining was left unattached at the head and tail until after the leather was turned in.

3. The new leather was adhered to the hollow tube and under the lifted board leather with WSP. The endcaps were formed and tied up in 18th C English style.

4. The original, lifted board leather was sanded at the edges and then readhered with PVAc and Lascaux 498HV.

5. The lifted paste downs were re-adhered with WSP and PVAc.

6. The losses in the end paper hinge were filled with digitally reproduced and printed replica endpaper (Hiromi, Senka-shi Thin, HM-35) adhered with WSP.

7. The original, faced spine leather was re-adhered to the spine with Lascaux 498HV. The facing tissue was removed with ethanol, micro-spatulas, and cotton swabs.

8. Areas of new leather at the head, tail, and joints were lightly retouched with leather dye to approximate the appearance of the original leather.