Imposition

Preparing the Forme for Printing

This work must be done on a truly flat and clean surface. A freshly wiped sheet of thick plate glass (so called ‘float glass’ is ideal) if you haven't got a traditional printers ‘stone’ (an engineers ground flat metal slab). Having composed and justified the type for the job, the next thing is to put it into the chase in the best possible way to suit the press and the job in hand. This is called Imposition, or ‘dressing’ the forme.

Lets say you are about to print a small job on an Adana 8 x 5 machine or something of the sort. Now there are traditional methods from the days of commercial letterpress work, but here they are a little modified to suit our special small press situations.

Into the Chase

Take a chase, and place it around the job; not exactly centrally but a little to the right, say half an inch or so. This will keep the centre of the pressure required still pretty much optimally central in the machine, but a shade to one side reduces an obscure inking problem. The achilles heel of most small presses performance is an imperfectly designed, inadequate inking system.

Roller Bearers

Then consider if the job would benefit from a roller bearer; a very thick printing rule, often made of wood, to type height and with slightly rounded ends. This adds positive drive to the rotation of the inking rollers, and prevents them skidding across the face of the type. This should be placed right against the right-hand side of the chase frame. That's assuming you are right handed, vice versa if left handed. Then add ‘furniture’ between that roller bearer rule^A and the right hand end of the set lines of type^B, so as to nicely fill the gap, using leads as required to fill up completely.

Between A and B (the roller bearer rule and the right hand end of the set lines of type) there has to be a gap which allows for the unprinted white margin of the paper for the job and, if possible, about 24pts for side lay quads.

Quoins

Now add a quoin  – or possibly two  – against the chase frame left hand wall, and pack out to fill the gap, up to the left hand end of the set matter, again using furniture and leads to completely fill. Leads should not come right against the line ends. Use wooden furniture/reglet, which grips better. Our ‘rubber side sticks’ can be useful here.

Furniture and Reglet

Now add furniture/reglet below the set matter to fill out to the bottom wall of the chase, add (usually two) quoins against the top wall, and then more wooden furniture/reglet – and leads if required – to fill the gap between the quoins and the top line of the set matter.

Locking Up and Planing

So now you have a filled (‘dressed’) chase, and can gently lock up a first time to move everything firmly down and to the right. Don't try to lift the chase yet.

Now loosen the quoins a little and ‘plane down the matter’: Use a piece of dead flat wood, laid on the face of the type  (and extending across to include that roller bearer if you've used one) and bang the wood with a clenched fist 2 or 3 times to make sure that all the letters (‘sorts’) have settled down on their feet, so their printing faces are all in exactly the same ‘plane’. The trade used a darn great wooden mallet for this and some wellie, but we can be much gentler with our small areas of type.

It's a gradual process. Start just half-way to locked in the top down direction, and then go half way to locked in the right-wards direction. Then lock up fully downwards and, finally, right-wards. Don't over do the locking, because you can readily bend a chase so it does not work with the chase clamping device on the machine or even, with antique cast iron chases, break them using modern quoins.

Now lift the chase slightly along one side, and press an area of the type with a finger, to see if it gives at all. If not, away you go: lift fully, place it into the machine and fix it in place. If the type moves – i.e. sinks under finger pressure – you have a problem.  Do NOT lift the chase up.  Lay flat down again,  unlock the quoins and look for the problem. 

What to Look For When Your Forme Won't Lock Up

1. A common offender is inaccurately cut leads between lines, causing a full stop or thin letters at the line ends to be displaced. When locking up, the over-long leads have taken all the pressure, so the letters in the lines aren't securely clamped.
2. It's entirely possible that you have a poorly justified a line. Or several! If possible, take that line out (firmly sandwiched between the leads from above and below) and ‘run it through the stick again’ – in other words, re-justify. This is a bind, and a classic situation for pie-ing the line. The alternative (bodger's) remedy is to slip a half-point copper space or two here and there in the line, but don't tell anyone I said so.
3. There may be dents in the furniture laying against the ends of the lines. There often is, and sometimes these can be trouble. Try rotating that piece of furniture or just replace it. Furniture, and indeed spacing, generally have an extremely long life far longer than type sorts. I have spacing in use from Frys foundry, which closed in the 1880s!
4. The chase can be bowed, and need some special remedial packing. For instance, on a 15 x 10" platen chase in wrought iron, the long side may bow so much under locking up pressure that the lines are visibly skew. 
   
   To solve this, use at least one piece of metal furniture (Cornerstone if you have it) against the chase wall with a little bit of 1pt lead at mid point, to take up the bow on lock up.  I haven't had this with Adana steel chases, but I have had the sides bow out enough to jam, and not allow the chase carry pins to enter the retaining grooves. Remedy: slacken the lock-up just a trifle.

Top/Left Lock Up

You will note that my suggested lock-up is from the top and left, not to have the quoins on all four sides, which is a commonplace with amateur printers. My method allows the removal of the forme, and e.g. a battered sort to be replaced, or some minor adjustment to the text made, the chase re-locked, replaced on the press and job and lays position not to be lost.  And you only need four quoins!

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