Knowing that all of your matter to be printed has to be locked together in a metal frame (the chase) leads to some important questions, the primary one being: how can I make sure that everything will be level and maintain its structure? This practice is called ‘lockup’. Where lockup is weak, it allows things to move within the forme and causes inaccuracies. In addition, loose material (like spaces) can work up from the forme to touch the printed page. This leaves a black square mark between words where the spacing material has been inked and printed.
In longer-run jobs the impact of rising spaces is magnified: if a space is loose and can work up on each impression, a movement of just 0.001″ per impression will cause the space to print on the page after just 500 impressions. In the world of commercial, high-volume letterpress this could be a massive problem.
The standard warnings appear here about cleanliness and accuracy. Make sure the bed of your press is clean, but also the back of the forme. If needed turn the chase over and rest it on some paper on the stone. Brush the back of the forme to make sure no debris will force a movement when it’s put in the bed of the press.
Ensure your materials are accurate: wood furniture will absorb some of the inaccuracies of your forme, but can also be affected by moisture and warping. Even the initial cutting of furniture could be incorrect. Most printers moved from wood to metal (aluminium) or formica (Resalite) furniture from the 1950s. Some wooden furniture is still needed to absorb some of the pressures in a chase. Make sure you periodically check that your chases are true by resting them on your imposing surface and seeing if the ‘rock’.
Tackle lockup in sections: by making sure each line is properly spaced; and then locking up work section-by-section you will find and correct errors much more quickly than by discovering an error just before you go to press.
During printing any movement of the machine or vibration will contribute to spaces rising, so the whole machine should be clean.
There is some specific advice for some types of matter —
- Monotype Matter
Should have most pressure for lock up applied at the top and bottom of the forme because the spacing between words is seldom as good as hand composition. When printing on a cylinder press it should be set parallel to the cylinder because top-bottom movement would be minimal
- Linotype/Intertype/Ludlow Matter
Should be checked for accuracy of the slug, especially where the foot of the slug is smaller than the head. In locking up this would lead to a bulge as the feet of the slugs meet each other and the head of the slug remains in place. This can be avoided by using thin paper or copper strips at the foot of the slug perhaps 0.002″ thick. An alternative is to use wet blotting paper that will dry to create a solid block. In printing on a cylinder press this should be set at right angles to the cylinder as left-right movement will be minimal
These should be checked to ensure they are true. Where they need some further leading on one side, this should be tacked in to place
Finally where a forme cannot be corrected there is a very severe option: mix resin and meths. Pour this on the forme and brush it away from the face of the type. The whole forme will now be a single, solid mass. At the end of printing, soak this in hot water to dissolve the resin and diss the type.