Clasp Restoration for 18th Century Book

Clasp Replication and Repair: Originally posted on bookclasp.com, 2004.

This is the first clasp repair I attempted, and it is really better viewed on the original web page in order to see all the steps properly. For this blog format I am posting a gallery of photos with numbers linked to the steps in order to illustrate the procedure I followed. Clicking on the images will open a larger version at the top of the post.

The set to be repaired was comprised of two volumes, part of a larger set of New Testament commentaries from 1734, bound in wooden boards and covered in vellum. Each volume was originally fitted with two brass clasps with brass hasps. One needed a replacement clasp on the top, two clasps/hinges on the bottom. New hasps were needed for both volumes.

Clasps of brass, or possibly bronze were originally attached to the boards with what looked like headless rusty nails for rivets. The clasps had a dark patina, possibly intentional, or possibly only due to age. I used the complete clasps on the other volume as a reference for modeling the new clasps and hasps. These were large, hefty volumes, at least 12″ X 15″ and about 3″ thick.

Metal used in the original clasps was heavy, about 20 gauge. The hasp was a lighter gauge, and was not flat but was hammered down its length to give it a curved, raised look. This was done most likely provide more stability in the hasp. The old clasps left some verdigris stains which were not removed. No other cleaning of the leather was done. The original clasps had taken on a very dark brown, almost black patina. Photos 1-6 below.

In order to get an accurate pattern for the clasp, a rubbing was taken of one of the remaining clasps on the volume. Twenty gauge (20#) brass was used to make the new clasps and 22 gauge for the hasps. The rods used to make the catches on the clasps were quite heavy, so 12 gauge brass wire was used to make them and also to make the hinge pins. A jeweler’s saw was used to saw out the clasps, because the metal was quite heavy.

Clasps were beveled and decorated to match the originals, with holes drilled appropriately. Hasps were measured and hammered to match existing hasps, and then they were hinged to the bottom clasp parts. Photos show various states of completion. Clasp parts were then given a brushed finish, and then scrubbed clean using an abrasive cleaner to remove any traces of oil before the patina was applied. Photo 7 in the gallery above

Finally, all the parts were colored with a commercial patina solution to give them a dark finish. Two close-up views of one of the finished replacement clasps are shown above in photos 8 and 9.

Attaching the Clasps

Before the clasps could be affixed to the book the paper paste downs were lifted to provide access the boards. The last vestige of the old rivets was removed and the old holes which held the rivets was repaired. Paste downs were repaired with a little thin Japanese paper.

To repair the holes in order to make it possible to rivet the new clasp back on securely, a drill bit the same size as as a small hardwood dowel rod was used to drilled through the existing hole in the board. The rod was trimmed to approximately the right length and then glued into the hole using Elmer’s wood glue. When the glue was dry the rods were carefully sanded flush with the inside board surface.