What is “Yapp?”
The simple answer is that yapp is the amount the cover overhangs the text block on leatherbound books (mainly Bibles).
But the complete answer is found by looking back in history.
The name “Yapp” comes from an English bookseller, from the second half of the 19th century, named William Yapp. It is actually a style of bookbinding where the cover, usually leather, overlaps the three edges of the book. The corners of the pages are rounded. The endpapers are frequently made from a textured paper and were usually black. So modern Bibles with wide margins on the cover should be said to be in a “Yapp style binding.” Since it is named after a person, “Yapp” should be capitalized.
If the flap on the fore edges (the long side of the page edges) is separate with square corners it is called “circuit edges.” This style allows the flap at the fore edge to lay flat against the page edges.
The extra cover hanging over is usually bent, or formed, close to the edges of the Bible. This can offer protection to the text block. It is also a stylistic element in some bindings.
The type of leather can determine the amount of Yapp with my binding style. Thick, stiff leathers are best with larger amounts of yapp. Very thin leathers may be too floppy for a well formed larger yapp.
Yapp size may be expressed as a set number. Common sizes are 1/4 inch (7mm) and 3/8 inch (10mm). It can also be expressed as a fraction of the total thickness of the Bible. Half Yapp, 3/4 Yapp and full Yapp are common.
As always, I am ready to help you customize your rebind. Together we can choose the right leather, the right yapp and all the other details of your custom rebind.
