Frequently asked questions with some answers
What is Letterpress printing
Letterpress printing is a simple process, basically it is relief printing using loose type, the term now includes other types of reliefe surfaces using the same equipment. Other forms of relief printing are Wood engravings (end grain) including wood type, type slugs (Intertype, Linotype, Ludlow), Wood cuts (cross grain), Lino cuts (Linoleum or other composites) as well as all the forms of chemically and mechanically prepared printing surfaces like etched plates (zinc or magnesium, sometimes aluminium, steel or copper) called blocks when mounted on a wood or metal base, engraved plates using routers and lasers as well as developed plates made of prepared polymers or liquid resins and vulcanised rubbers used in flexo and rotary letterpress. Most of the primary surfaces were reproduced in the past as stereotypes and electrotypes for high speed presses and to make working duplicates that were better suited to storage.
- Stay open/proofing ink, does not dry, soaks into paper, used on proof presses to avoid regular washup
- Oil based inks, traditional
- Rubber based inks, work better on some surfaces, stay open on the press for longer
- Soya based inks, some of the linseed oil is replaced with soya oil, similar characteristics, perhaps greener
- UV cure inks, suitable for certain non absorbent substrates, need post UV cure
- Water based inks, not suitable for metal type (or distributor rollers), can be used with wood or lino cuts
- Artists oil colours, useful for small amounts of colours for tinting and testing
Hand Set Type, basic differences
- Brass type – individually engraved, used for foil blocking, durable and expensive, very limited designs, rare
- Zinc/Mazak type – Cast for foiling work, durable, limited designs, uncommon
- Foundry type – Traditionally hand cast, now cast by machine by a short list of foundries, durable, expensive, some still available second hand and the occasional unused old stock. Suitable for foiling and letterpress
- Monotype – machine cast, can be machine set and output on a Monotype Composition caster in ready set lines (up to about 14 point size) or in fonts for hand setting, cast on a Monotype Super Caster in larger sizes, suitable for less demanding foiling work, long life with carefull letterpress work. Second hand, unused old stock and new is usually available
- Wood type – Some still available second hand, not much made any more (Hamilton Wood Type and Printing Museum still makes), traditionally condensed fonts in the larger sizes for posters, broadsides and headlines, can get very large
The printing measurement system was a in house affair for a long time. A mumber of times steps to standardise it were taken. The largest group of users were the Anglo – American printers and they eventually standardised on the point system. This is a set of measurements where one inch is made up of almost exactly 72 points. Pica was the font size that was selected as the 12point font in the new system. An Em quad in any font is as wide as it is high so a Pica (12point) Em quad is 12 pt high and wide, hence a ‘pica’ or ‘pica em’ is used to describe a length of about 12pt (almost 1/6 th of an inch). When typesetting was computerised Adobe et al decided that it would be easier to round the number of points in an inch to exactly 72 and that it the point size supported by all desktop publishing applications, early Macintosh monitors and many dot-matrix printers supported a resolution of 1/72 of an inch, equal to the new digital point size.
Like the linear measurements of the type the height was also open to much variety and fonts from one foundry would not match those of another and could not be simply mixed. In the end a height of .918 inches was selected as the standard for the type height (cast slugs and wood type too) and still remains so to this day in the Anglo – American system. Stereotype, electrotype and photochemically etched plates are traditionally mounted onto wood or metal blocks or raised honeycomb based to come up to the same height so they can be mixed with other elements in the press. Lino cuts, wood cuts and wood engravings are also made or mounted to this height to allow use in standard presses.
Type metal safety
- Don’t poke your finger into the molten typemetal in a slug casting machine.
- Don’t ingest any bits of typemetal and wash your hands with soap after working with it.
- Mop or vacuum type metal dust rather than sweeping.
Much has been said about paper for printing for letterpress. These days the requirements are different from 50 years ago. At the height of the letterpress era almost any paper could be made to work, the craftsmen were skilled and a suitable means would be devised, obviously certain papers were better suited to certain work and half-tone photos would be printed on smooth coated stock. These days the trand is returning to the historical papers with more cotton rag content for the bulking and archival qualities. Hand made paper (especially in a laid mould) has also been a tradition that is held in high esteem because of the durability of the paper and historical correctness for hand printed works. Hand made paper tends to wards more bulk and a rougher surface and as such lends itself to being printed when damp, this often results in output that is a sight to behold.