Look­ing at wheth­er ‘squeeze’ can hap­pen; what the effects are and how they can be avoided

The word ‘squeeze’ sounds like one of those pass­words that are used by the print­ing world simply to add to the mys­tique of let­ter­press.  It’s true that it has been used in the past by some print­ers to jus­ti­fy some very impre­cise prac­tices.  That said, squeeze is some­thing for print­ers to think about, espe­cially those con­cerned with pre­ci­sion.

After World War II the gen­er­al drive for great­er pro­ductiv­ity and qual­ity meant print­ers needed to adopt ever more pre­cise ways of work­ing to avoid prob­lems dur­ing print­ing and also increase the pro­duct­ive hours of each machine.  Where once objects like fur­niture and blocks could be points adrift from their stated size, they now had to be correct.

‘Squeeze’ is the term to describe the dif­fer­ence between the length of a line of type as sat in the com­pos­ing stick; and the same line when locked up in a chase ready to print.  The accep­ted view was that a com­pos­it­or should set type a little longer than the meas­ure (line length) but the forces of quoins would squeeze the type togeth­er and bring it back to the inten­ded size.

Know­ing that type met­al itself can­not usu­ally be com­pressed, we have to look at what else could cause this phenomena –

  • Dirt and oth­er depos­its on the walls of type might be compressible
  • Bent spaces might be brought back in to true
  • Type that is not straight in the stick (‘off its feet’) may be cor­rec­ted to an upright position
  • Basic equip­ment, like the com­pos­ing stick, might be inaccurate

It fol­lows, then, that if clean new type is used in an accur­ately made and set com­pos­ing stick and the line is prop­erly jus­ti­fied then there is no room at all for com­pres­sion and so squeeze is elim­in­ated.  Remem­ber that the pres­sure of the quoins on the spe­cif­ic lines will be around the same as the pres­sure of the com­pos­ing stick ends.

The prob­lem then becomes ‘how can the line be accur­ately filled’, for the end­less com­bin­a­tions of char­ac­ter widths and stand­ard spaces will always leave some room at the end of a line.  As an example, a line of 14pt type is set and a gap at the end of the line is too small to be filled with a thick space, and too big to be filled with a middle space.  The dif­fer­ence between the two is 1 and 16 of one point.

Nat­ur­ally spaces can­not be made in each pos­sible size, so if we are using the pre­ci­sion approach above every line will be short because an irreg­u­lar space will exist at the end of each line.  Our answer now is to make sure that, on aver­age, each line is correct.

To do this we have to estab­lish a com­mon space: what is the aver­age dif­fer­ence between any two stand­ard sizes of space.  Just how big is the jump between mid and thick; or thin to mid; or mid + thin to nut?

Sav­ing you the maths, the answer is 7/120ths of an em, and con­vert­ing this to points the aver­age is 712th of a point.  That is to say that any giv­en com­bin­a­tion of type and stand­ard spa­cing will be between 724th over line length and 724th under line length.  We have to fur­ther round this to a usable unit, and the key point is to set your com­pos­ing stick to ½pt over the desired line length.

To make the best of this, the fol­low­ing points should be observed –

  • Com­pos­ing sticks should be peri­od­ic­ally checked for accuracy
  • Pre­ci­sion, milled, em gauges should be used to set the stick along with a half-point gauge.  All sticks should be set from the same gauges
  • When using type over 14pt, use half-point ‘hair’ spaces
  • Leads should be cut to the line length minus one point
  • Reg­let should be used down the sides to pages to take any remain­ing irreg­u­lar­ity in justification

None of these prin­ciples apply to Mono­type mat­ter (unless being cor­rec­ted) or Lud­low or Intertype/Linotype slugs as these are cast to pre-defined lengths exactly.