Yet anoth­er let­ter­press advant­age: using the impres­sion of the press to add unique num­bers to the page

Letterpress Numbering Machine (from Flickr)
Let­ter­press Num­ber­ing Machine (from Flickr)

Anoth­er advant­age of the let­ter­press pro­cess is that the act of impres­sion allows num­ber­ing machines to be used: the print­ing sur­face is changed each time the paper hit it.  Litho, by con­trast, must use the same, stat­ic plate for each impression.

Cap­it­al­ising on this, spe­cial­ist man­u­fac­tur­ers designed num­ber­ing machines known as ‘num­ber­ing blocks’ or ‘clocks’ by dif­fer­ent print­ers.  The prin­ciple is that when the impres­sion is made this pushes down a plun­ger which forces numbered wheels to rotate.  These num­bers are inked and so leave a dif­fer­ent num­ber with each impression.

Num­ber­ing is needed on many doc­u­ments: invoices, receipts and draw or raffle tick­ets being the best examples.

Num­ber­ing machines are very clev­er pieces of equip­ment as they have to jointly meet the spe­cific­a­tions of a num­ber­ing machine, but also a piece of the let­ter­press forme.  As such they demand a lot of care and atten­tion: they should be thor­oughly cleaned after use with a spe­cial­ist flu­id, then oiled with a high-qual­ity light machine oil and finally stored in a sealed box.

In terms of using them to print there are some spe­cial pre­cau­tions to take —

  • In order to pos­it­ively depress the plun­ger, you might have to use a very hard pack­ing per­haps using a brass or lead rule to take the force of the plun­ger.  You should cut an out­line to receive the brass or lead from the pack­ing to assure that the end res­ult is roughly the same depth as the original
  • If you’re using a cyl­in­der press (a proof­ing press, Wharfedale or a Ver­tic­al Miele-type press) then you need to make sure that the plun­ger is depressed first as the cyl­in­der travels over the num­ber­ing box: this will make sure the num­bers are in the cor­rect pos­i­tion to receive the ink and impression
  • Think care­fully about print­ing first and then num­ber­ing in a second run so that re-num­ber­ing does not have to be done for the sake of a single spoilt original

Com­mon prob­lems, and their solu­tions are —

  • Speed
    Num­ber­ing machines are tested to 16,000 impres­sions per hour which is around twice the usu­al speed of the fast­est let­ter­press machines.  Prob­lems with num­ber­ing machines are rarely from too high a speed; but there is some anec­dot­al evid­ence that too low a speed can cause problems
  • Num­ber­ing block does not advance a number
    When lock­ing the num­ber­ing machine up, care should be taken to make sure that the lockup is not too tight for this will pre­vent the machine from work­ing correctly
  • Nearby char­ac­ters are not printing
    If pre­fixes are needed for the num­ber (for example, to num­ber books sequen­tially as Book No. 1 / Invoice No. nnn) then the type in the forme should be at least two inches away from the num­ber­ing block.  There is a tend­ency for rollers to bounce on the high­er-than-type-high plun­ger and so not deliv­er ink on these pre­fixes.  A rather extreme altern­at­ive is to file a piece of type to fit in place of the plunger
  • Rollers are caus­ing the num­ber­ing block to advance
    As well as rais­ing the height of the rollers, it might be pos­sible to cut away the por­tion of one roller that will pass over the plunger

Manual Numbering

Num­ber­ing by hand is still an option for short­er runs, and might be prefer­able where time is not in short sup­ply.  One tip is to avoid any regis­tra­tion marks — for example, the pre-prin­ted ‘No.’ — so that the manu­al num­ber­ing does not show as being out of register.

Numbering Schemes

Over time many print­ers developed timesav­ing schemes in print­ing numbered work.  Two are described below.

For those print­ing ten-up (that is, ten num­bers to each page) it should be pos­sible to pre-print the last digit in the forme (num­bers 0 to 9) and then use ten num­ber­ing blocks in front of those num­bers which will advance on each impres­sion.  So, once the num­ber­ing blocks are at 87 that will print 870, 871, 872 to 879. across the page.  On the next pass the final digits remain the same but the num­ber­ing block moves on by one, so print­ing 880,881, 882 etc.

If no num­ber­ing blocks are avail­able, or lar­ger types are needed (run­ners num­bers in a race, for example) then it’s pos­sible to get through twenty forme changes for 99 num­bers rather than 99 forme changes.

  • Set and print ten of each of the second char­ac­ter.  Place them in ten piles of 0 to 9
  • Change the forme to now have a num­ber 0 in the first pos­i­tion.  Take a sheet from each of the ten piles and print these.  It will gen­er­ate a 00, 0 (from the second pass) and anoth­er 0 (from the first).  Pass 9 will cre­ate 09
  • Now change the forme to have a num­ber 1 in the first pos­i­tion.  Using the sheets from the piles, your first print here will cre­ate a 10, 1 (from the second pass) and anoth­er 0 (from the first pass)
  • Con­tin­ue chan­ging the first num­ber until you reach 99!