A printing frame –chassis presse in French or pressino/torchietto in Italian- is an essential instrument for every printer of alternative techniques and historical processes. Almost the totality of the antique print techniques is contact printings. It is therefore necessary a perfect adhesion between negative and printing support to gain all the finest details and even the presence of unpleasant flou zones. Moreover, it is necessary to inspection the print to determine the correct exposition without losing the register between negative and print.
These two fundamental characteristics of the printing frames are easily obtainable on little size. The traditional printing system is less and less efficient when working on sizes bigger than 20x30cm. It is then necessary an expensive and often loud vacuum pump system.
Using an innovative pressure system the printing frames I use solve the problem of bigger formats. Furthermore this printing frame is versatile (it is possible to print on support with different thickness), user friendly and has a quick opening. Still it conjugates all those characteristics with many little forethoughts, which are the result of years of print experience, attempts and prototypes of printing frames. It is a complete and versatile tool.
The printing frames I use are entirely craft handed made. More than the aesthetic aspect, versatility and details attention, it is conceived to give the best pressure, obtained thanks to perfect bottom flatness, front rank materials, the knobs system, etc…
The whole is an essential precise instrument made for every contact printer that wants to make the most of its big negatives.
Printing frame specifics
Total encumbrance: 46x62x9.5cm (with pressure mechanism totally extended; minimum is 6.5cm)
Weight: 5500 g
Frame dimension: 44x62cm
Maximum image dimension: 38.5x56cm
Maximum paper format: 40.5x58cm
Glass thickness: 3mm (augmentable up to 5-6mm)
The chosen dimension allows the print in A3+, the hugest normally used since digital negative has changed the printing habits of contact printers. The choice of the print support sized 38x56cm let the printer use, without any waste, the half of a 56x76cm paper, one of the most used size of the beaux-arts paper constructors. A 38x56cm paper gives an A3+ image with a frame of 4cm. Obviously the printing frame can be used to print without waste on a quarter of a 70x100cm paper, another standard size of paper constructors. Or even print a negative smaller than an A3+ on a bigger sheet, so that borders are wider.
Even if it is possible, augmenting the chosen dimensions requires stronger pressures, supported only by thicker plates that expand the exposure time. Not using vacuum pump also augment the risk to obtain flou zones and irregularities. The use of bigger sizes, like 50x70cm for example, is to be looked after.
Printing frame constructions materials
The knobs are applied to the structure of the frame and the spring, which are realized in tuliptree. It is a strong wood with compact fiber that guarantees a perfect dimensional stability and the maintaining of the square mount, even after months of strong pressures.
Its bottom is realized in marine plywood of pine-tree. Multilayer, crossing the wood levels in different directions, guarantees the flatness of the bottom time after time, essential characteristic for a printing frame to compress paper in a uniform manner. The marine plywood, more than being water resistant, has better quality than the common multilayer.
Bottom, structure and springs are painted with several coats of wood preservative and finishes to guarantee the conservation of the printing layer and keeping the natural wood color.
The inner bottom part is covered with opaque black felt, to compensate paper and wood irregularities.
Hinges, quick closures and pressure knobs are realized in steel.
Pressure system of the printing frame
Pressure historically unites papers and negatives inside printing frames for contact printings and two or more springs ensure the compression of the bottom toward the structure. This system has several disadvantages:
- Even if springs offer a certain elasticity, it is not possible to significantly modificate the thickness of the print support. It is not possible, for example, to use the same printing frame to print on paper or on wood or glass plate.
- All of the materials loose elasticity as time goes by. Even steel made springs slowly adapt and take the shape due to the pressure. The printing frame gets less and less efficient. To obviate the problem, the majority of the printers add thickness between the bottom and the print with layers of materials such as felt, neoprene or even cardboard. Inspection from behind during exposition is therefore difficult or even impossible.
- Big printing frames need lots of springs to equally distribute the pressure points on the bottom. As a result the process to open the bottom part and position the print is long and difficult.
To obviate all of those drawbacks, I created an innovative pressure system that makes stronger, longer, finely adjustable and independent pressures that also adapt to support thickness. Everything is conjugated into a user friendly and a quick system of print opening and inspection.
Each one of the three panels of the bottom is compressed by a traverse with two pressure knobs, which means six total points of pressure on the bottom of the printing frame.
The pressure for each knob can be regulated independently and finely, turning a register of adjustments. The block-system keeps the chosen pressure level, without registering the pressure between two prints. The system has to be re-calibrated only when the support thickness substantially varies. It is also possible to print directly on the support itself only removing the bottom part, as when printing on thick materials such as wood.
Pressure knobs couples are mounted on traverses, hinged at one side of the structure and blocked by a quick jerky closure on the other side. It means that, once the pressure is okay, the printing frame can be opened and closed rapidly, working only on the three jerky openings that block the traverses.
Between the knob and the back bottom there’s a gum that compensates the pressure irregularities, similar to the classical spring conception. The huge advantage of the system is versatility that can be adapted to the most varied exigencies.
The system is projected to concentrate the pressure at the center of the image, leaving the problems for the borders, where there’s generally a white frame, without harming the print itself (using an A3+ negative format, the free margin measures some centimeters).
Finally, when it’s not used for ages, knobs can be easily unloaded, to have a minimum pressure that keeps the printing frame closed without stressing the structure to a long and intense pressure.
Some more printing frame characteristics
The color of the felt layer on the base is opaque black, to minimize the reflection of light on the bottom. In fact, when printing transparent material such as glass or films, the light that bypasses the clear part of the negative also passes through the transparent support and the bottom of the printing frame spreads it, printing a shady image. This printing frame, thanks to its black base, can be also used to duplicate contact negatives.
The base is divided into three panels and it is entirely removable for the printing positioning. To control the exposition, the two lateral panels can be independently opened, together or one lateral with the central one. This system allows the contemporary inspection of two third of the image and the access to the entire image, allowing the control of the exposition in every point. Lateral panels are gifted with rings that make taking and opening easy.
Hinges of bottom panels are T milled, so that the base is impenetrable for light. This is an essential characteristic not to obtain exposed lines on the print in correspondence to the junction lines of the three panels, due to infiltrations from the back.
Frame inner borders are made to eliminate shadows of the frame itself from the image area, problem that particularly afflicts the frame layers with a light point source. It gives the possibility to completely use the designated image area and avoid the common exposition irregularities near to the borders.
Glass can be completely removed, to facilitate a complete cleaning or washing, or the substitution if broken. The plate never touches the wood but the felt and a neoprene band interposed between the glass and the frame of the structure. This way, pressure doesn’t concentrate on wood imperfections or on little grains that could intervene between glass and structure, one of the principle causes of negative brake on glass.
Printing frame variants
When printing on exceptionally thin and wrinkly papers, it could be necessary to augment the pressure stronger than the normal levels. Glass must be substituted with a thicker one, to pushes the limits of the pressure knobs and not breaking it. A thick glass can lengthen exposition times and that’s the reason why the printing frame has a standard glass of 3mm that stands pressures able to keep all the used prints supports.
It is possible to ask for personalized printing frames, to print on materials thicker than 2cm. The print area can also vary. Special printing frames that accept even 50x70cm size are available. It is also possible to order printing frames that prints negatives on 40x120cm rolls, with 6 bottom panels and 12 pressure points.