We recently picked up a 12 volume set of a collection of Martin Luther's Works for a rare book dealer friend of ours. These books are beautiful and unique. This image of Martin Luther on the alum tawed cover is a spectacular example of block tooling in the 16th Century. On most of these volumes the recto has an image of Martin Luther, and the verso has an image of Philip Melanchthon, Luther's collaborator.
There is evidence that originally these block pressed images had gold in them, but over the years the gold has fallen out. Before the invention of the block press in the 1830s, binders would press engraved images into leather by heating the block, then laying it on the cover, and then pressing it in their screw presses.
There is a misconception that blocking is an invention of the 19th Century, which is obviously not the case. We often hear people say that prior to the 19th Century all book decoration was done with small hand tools, and the invention of the blocking press has given a bad name to blocking altogether. But while aesthetic tastes change over the centuries, as historical binders or as lovers of historical books we should be careful to not let taste dictate historical accuracy.
There is a time and a place for all tooling styles, and it is okay to appreciate them all even if they're not your personal favorites.
We love the fine detail and negative space of the background contrast an engraved block offers, that can't be achieved in the same manner using small hand tools. The artistry of these blocks creates an impression well fitting the era in which these books were made.