Printers' ink ball or dabber

Early Rollers, Composition Rollers and Rubber Rollers

Print­ers’ rollers have occu­pied the greatest print­ing minds since the early 1800s.  While the rotary let­ter­press machine should have improved pro­duc­tion speeds, their poten­tial was held back by the lack of rollers: just how could ink be trans­ferred to the forme with speed and con­sist­ency?  This art­icle looks at early rollers, com­pos­i­tion rollers and rub­ber rollers.

Early Rollers

Printers' ink ball or dabber
Print­ers’ ink ball or dabber

When using the ori­ginal hand presses, print­ers used ink balls.  A wooden handle and sheep­skin bag filled with horse­hair formed the ink ball, and these were used in pairs.  The inker could ‘mill’ the ink between the balls and then apply ink to the forme before print­ing.  This approach was used between in inven­tion of the press and 1790, some 340 years.

With the intro­duc­tion of the rotary press, print­ers simply mod­i­fied their exist­ing tech­no­logy and built wooden rollers with a sheep­skin cover filled with horse­hair.  While made with some pre­ci­sion, they could not coat the type effect­ively, and left a mark on the page where the stitch­ing in the sheep­skin cover did not trans­fer ink.

Com­pos­i­tion Rollers

In 1818, Robert Har­rild developed the first ‘com­pos­i­tion roller’, made of glue (from calf­skins) and treacle — his devel­op­ment was based on the pro­cess used by the Stafford­shire Pot­ter­ies to add pat­terns to pot­tery.  While this mix­ture was tacky enough to carry and trans­fer ink, the ingredi­ents led to an instabil­ity of the roller.  The glue gives up water in dry atmo­spheres and shrinks and cracks.  In damper con­di­tions, the glue takes up mois­ture and the roller swells.  Thomas de la Rue added gly­cerol (US: gly­cer­ine) to that ori­ginal mix.  Gly­cerol has a tend­ency to absorb mois­ture from the air and this bal­anced to a degree the effects on glue to pro­duce a more stable roller.  Rollers still had to be made to suit the atmo­spheric con­di­tions and sea­sons — so rollers were made to dif­fer­ent recipes in dif­fer­ent parts of the world, and depend­ing on whether it was sum­mer or winter.

Mak­ing Com­pos­i­tion Rollers

Just as print­ers were expec­ted to make their own inks, they were also expec­ted to be able to cast their own rollers.  Presses (like the Arab) were sup­plied with roller cores (the cent­ral metal bar) and moulds for the com­pos­i­tion.  Print­ers would routinely melt down and re-cast com­pos­i­tion rollers.  A big prob­lem was to pre­vent air bubbles from sit­ting on the edges of the roller, and caus­ing small marks that trans­ferred to the inked forme.

Com­mer­cial makers of com­pos­i­tion rollers used a gat­ling gun to hold mul­tiple moulds and pour com­pos­i­tion mix­ture into all of them at one time.

Using Com­pos­i­tion Rollers

Adana recom­men­ded four sets of rollers: two pairs of rollers each for sum­mer and winter; one for col­our work (includ­ing white) and one for black.  Rollers would be used for col­our first and then black.  Rollers should be care­fully cleaned and covered before stor­age using oil or pet­ro­leum jelly.  An appro­pri­ate mix would be 10% med­ical par­affin plus ‘suf­fers grease’ (an engin­eers’ jelly).

Com­pos­i­tion Rollers Advant­ages and Disadvantages

Advant­ages of Com­pos­i­tion Rollers

  • They are the cheapest rollers to make of the major roller materials
  • Ingredi­ents can be var­ied to suit local conditions
  • They are sup­plied soft (typ­ic­ally 15 — 20 shore) and this can roll ink to mul­tiple levels within a forme
  • They are easy to wash up
  • Com­pos­i­tion rollers have a very smooth sur­face that can deliver a sharp appear­ance on prin­ted material

Dis­ad­vant­ages of Com­pos­i­tion Rollers

  • They are less stable than other rollers in dif­fer­ent tem­per­at­ures and humidity
  • Cuts in the roller will spread and widen
  • They can­not be made to the same accur­acy as other rollers
  • They occa­sion­ally swell at the end

A UK-centric view of letterpress printing