Gold in its leaf or very thin sheet form can be applied to most surfaces including leather. Gold leaf is applied over a specific type of glue called sizing. This glue provides a surface for the leaf to attach to. Lettering or adding a name to an existing leather book can most easily be done if the leather surface can be laid flat for the stamping of letters. It can be accomplished on the spine of a leather book without stamping if the person gilding the leather book has sufficient mastery of letter carving on leather.
Clean the cover of the leather book to remove any dust, dirt, debris or oils. Identify the area where you wish to add the name to the cover and use a straight edge and painter's tape to create a straight line that the bottom of the letters will touch. If you intend to letter in several rows you may need to repeat this process several times. Mark the start edge of your first letter with tape that is perpendicular to your lettering tape.
Assemble the letter stamps you need for your name. Tape a piece of similar leather scrap to your work table and tape it off to mirror your book. Practice stamping letters in your leather sample using the stamps and a leather mallet. This will assist you in letter spacing, how many letters will fit on a line and how to keep your letters straight. Your finished product will look best if the stamps are straight, even and of equal depth.
Stamp your book cover once you are confident that you know how to work with the stamps. If you are stamping the spine you will need to support the leather by placing wood or metal between the leather and the book signatures. If your book is fragile you may need to have spine work done by a professional book repair company.
Dye the stamped areas so that dye goes into the creases. Use a 1/8-inch artist brush to keep the dye in just the areas of the stamping. Dye will add visual depth to the stamped creases and improve how the lettering will look when finished. Allow the dye four hours to dry completely.
Apply an antique under-finish to the stamped letters using a 1/8-inch artist brush. This finish should only be painted onto the leather areas where gold leaf will be applied. Allow the under-finish eight hours to dry completely.
Paint gold size to the letters where you want to add the gold leaf. Allow the size to become tacky (about an hour after applying) this allows you to apply leaf for about 20 to 30 additional minutes before the size dries completely.
Cut your gold leaf sheets using a butter knife. Pick up the sheet with square tipped tweezers and drift the leaf down over sizing. Gold leaf is extremely fragile so it is more like guiding the leaf through the air than placing it. Once it touches the size it will cling. Press the leaf into the lettering using a stiff 1/8- to 1/4-inch stiff artist brush. You can also use cheesecloth to blot and lightly brush at the leaf.
Clean away any stray bits of gold leaf using a Q-tip. Rub the gold to smooth it out using a soft cloth. Paint the lettering with antique finish. Allow the finish to dry completely (overnight) and apply a clear lacquer finish to protect the surfaces and the gold. Allow 8 to 24 hours for the lacquer to dry completely.
Always do gilding work in a draft-free room where you will not be disturbed. Because gold leaf is so thin even slight air disturbances can displace costly gold sheets.