Below are some of the most popular questions about antique maps.
Prices vary for the same printed map because no two printed maps are identical. There are a number of factors that affect printed maps in varying degrees. Here are a few:
Centrefold. Most large maps when published in atlases were folded in half with a guard pasted to the fold. This guard was bound into the book and allowed the map page to lay flat without diving into the binding obscuring detail and is not, of itself, to be considered a fault but for some maps that were published either folded or flat, the unfolded examples are preferred. The folded paper is weak, vulnerable to wear and easily damaged, particularly at the bottom and may have splits or tears and are commonly found with repairs.
Margins. The unprinted area surrounding the map varies greatly between publications, the 17th century Dutch publishing houses of Blaeu and Jansson for example, printed their maps with large generous margins but the small pocket atlases of the 18th century, in keeping with producing pocket volumes, often lacked an appreciable margin. Large margins protect the printed area of the map from nicks and tears at the vulnerable page edge including the centrefold. Margins may be reduced later in the life of the map as a result of trimming by the bookbinder in a rebinding or aesthetic preference by a picture framer.
Discolouration. Paper can be affected by many materials and substances. Atmospheric factors can affect any impurities in the paper causing browning or spotting (foxing) most usually on 19th century paper. Offsetting from the printing ink or early hand colouring can be unsightly. Early colour contained pigments that could adversely affect the paper, especially greens containing verdigris which can be a good indicator of original colour by the staining that can be seen on the back of the map but which can also cause damage. Inferior framing materials contain acids which can leach into the map, damaging the structure of the paper and browning the page - this can occur over the whole map when acidic backing materials have been used, and is also commonly found as a brown line around the map border from the inferior mount board. Framed maps can also be subject to fading, particluarly of the colouring if exposed to sunlight or UV.
Visible damage and repairs. It is always more desirable for maps to be undamaged and without repairs and such maps have higher value. For rarer maps some damage may be acceptable and becomes a question of degree balanced with the scarcity of the map.
Antique printed maps may have been sold and published as loose sheet maps, in part issues by subscription, or bound in book or atlas form. Over the years maps can become damaged by use, neglect or accident and by far the most likely to survive are those that have been bound into a book or atlas, the book affording protection to the individual pages.
Many books and atlases have been 'broken' over the years for the maps and prints they contain. Most of us like to think that individual maps have been taken from atlases that will have been too expensive to repair but unfortunately that is not always the case. Arguments are made that all maps began as a loose sheet map before they were bound into books and while individual maps are affordable to most, many complete atlases are not, and the plates contained in them would therefore stay hidden on library shelves.
It may always be a contentious issue but I confess to having gained great pleasure from antique maps and am grateful that they are out there and available to enjoy.