Short videos are rarely as satisfying as this! Would love to see the end result.
Short videos are rarely as satisfying as this! Would love to see the end result.
Useful tips to make sure your rollers can ink type properly
Since the general purpose of a press is to ink a printing surface and impress paper against it, roller height has a big part to play in quality printing. For the smallest printers there are the “small printer” approaches of setting large capital letters in the chase; inking those letters and then inspecting to see whether the face is inked, and whether ink has been transferred to the beard of the type. The ideal is to have fully inked the surface with a minimum of ink being applied to the beard of the type.
The next stage is to use a roller setting gauge. These come in various shapes and sizes. We’ll look here are the basic type that most small commercial printers would have. Flat gauges are typically a block of metal machined to 0.918” high with a long handle: and have the advantage that they tend not to tilt and so skew the results. The aim here is to see a thin film of ink over the surface. No ink indicates rollers are too high; and ink that has been smeared or left on the sides indicates rollers are too low.
Cylindrical gauges are more common but can tilt when used. The aim here is to see a thin strip of around ⅛th of an inch of ink on the top of the cylinder.
A further step to precision was to use a spring-loaded setting gauge that included a dial or marker to show how low the rollers were on the machine. I am yet to see one in use!
The Netherlands Graphic Arts Research Institute worked on establishing realistic tolerances for letterpress materials. They suggested that type would still print perfectly if it was within 0.0008” of 0.918”, and so any efforts to be more precise than that would be a waste.
F C Walter, writing in Print in Britain repeated that he had heard a lecturer stressing the need to be within an overall limit of 0.0015”, and commented that it would work “precision and the printer to death”. He foresaw that a “…printer, who has toppled, drunk with fascination into precision-land where everything is beautiful but useless.” He proposed an overall limit of 0.0030”. The reasoning was that 0.0015” could be so easily disrupted by standard printing processes (like planing) that it could not be achieved. In context 0.0015” is around ¾ of the thickness of a cigarette paper.
Historical article from 1934 examining ink developments
Progress in the improvement of printers’ materials is nowadays so rapid that it is highly important for the printer to keep in touch with modern developments in the basic materials of the trade. The main advances in printing ink technology have been the progressive improvement of colours, varnishes, grinding methods, etc.; the introduction of outstanding properties in commonly used inks; and the discovery of entirely new types of inks. These notes are intended to give a few modern lines.
The aim of the ink maker is to produce inks which can be used straight from the tin without having to be doped by the addition of boiled oil, driers or similar materials. A first-class black should, without incorporation of any other material, possess the following properties:
With regard to the last point, we all know that different classes of paper behave differently with the same ink. It is easy to formulate an ink which does not set off on one paper yet sets off markedly on another. Realizing that the printer’s choice of paper is often limited by practical considerations, the ink maker so formulates his standard lines that they are usable on as many different papers as possible.
The modern introduction of high-speed presses has led to the making of special inks for these machines. An ink which has given excellent results on a comparatively slow machine may spray badly when it is tried out on a fast-running one.
During the past year or two, much attention has been paid to improving the setting of blacks and preventing set-off. There are now obtainable some new blacks, the physical properties of which are such that there is a very rapid and firm set on the paper, allowing of quick backing up, while set-off* is eliminated.
It is rarely indeed that the ink maker puts into his bronze blue inks any driers such as cobalt, manganese or lead. This is because the bronze blue pigment is itself a powerful drier, and being, of course, present in very high proportion, causes rapid drying and skinning.
Expressed differently, bronze blue, like cobalt, manganese and lead driers, is a catalyst for the reaction between linseed oil varnish and oxygen—that is, bronze blue is a substance which increases the rate at which the linseed oil varnish, which is present in the ink, combines with the oxygen in the air to produce a dry film. Catalysts are used for quickening up many chemical processes.
When the printer requires a bronze blue ink which will not skin on the rollers in, say, two days, the ink maker is faced with a problem of a different type from the usual problem of driers. It is, of course, impossible to reduce effectively the bronze blue which is at once the pigment and the drier. Tiie problem is best solved by using a substance, known as a “negative catalyst,” which behaves in the opposite way to an ordinary catalyst; the negative catalyst reduces the rate at which the ink skins. By using the right negative catalyst in suitable proportion (only a very little is required), it is possible to produce a bronze blue of brilliant lustre which will not skin or dry on the rollers even in two days and yet will dry satisfactorily on the paper.
Coloured News Inks Although coloured news inks are by no means new, it is only in recent times that they have been used to any large extent for advertising purposes. Good quality coloured news inks, which work well and do not fill up even on long runs, are now obtainable at a price suited to newspaper work, and it is probable that the near future will see a considerable increase in the amount of coloured advertisements.
Aniline inks are being widely employed nowadays with good results. These inks consist essentially of dyes dissolved in methylated spirit, while other ingredients are added to impart fastness to water, brightness, etc., and to prevent excessive drying on the rollers.
Aniline inks are much used in paper bag and similar manufacture. The drying of the inks is mainly dependent on the rate of absorption and evaporation of the volatile spirit, and since this is very fast, the printed sheet can pass directly from the rubber stereo to be processed into the completed bag.
Generally, a good aniline ink will be found suitable for most papers, but there are a few exceptions. For printing on kraft paper, for instance, special anilines are generally required in order to obtain the maximum brightness of colour. Special surfaces like tinfoil and cellophane also require special inks for best results.
Where transport charges become considerable, as is the case with exported inks, aniline syrups may be used instead of aniline inks. These syrups are so made that when one part of the syrup is mixed with two (sometimes three) parts of methylated spirit, the resultis an aniline ink. The stronger syrups (those to be mixed with three parts of spirit per one part syrup) are so concentrated that, in the case of some (not all) colours, the syrup may be rather too viscous and may not immediately mix with the spirit. It is, therefore, recommended that those syrups, which are convertible by adding two parts of spirit to one of syrup, should be used, as these never give trouble on mixing. These latter syrups are of course cheaper.
Special syrups are obtainable for use on kraft papers.
A little may perhaps be said about letterpress printing of black and coloured inks on surfaces such as cellophane, celluloid and glassine. Inks for these materials dry almost entirely by oxidation—there is practically no drying by absorption or evaporation. Consequently special quick-drying varnishes are used.
The printer should carefully avoid the introduction of any non-drying ingredients into such inks. For instance, in washing up previous to a run, particular .care should be taken to remove traces of wash-up liquid from the rollers and the forme. If the printing were done on ordinary papers, the presence of a little non-drying liquid would not matter so much— although here, too, there is an element of danger. On non-absorbent papers, however, the danger is considerably increased, because the non-drying liquid remains with the ink on the surface and may seriously hamper the hardening of the print.
When the first experiments were made towards producing metallic letterpress inks, the main difficulty was to combine the desirable properties of resistance to rubbing, extremely high lustre, and non-drying on the machine during printing. A very large amount of work was in fact done on this problem, with the result that exceptionally brilliant inks which do not wipe off, or otherwise misbehave, are on the market.
More recently, metallic photogravures have been introduced, and the efforts of ink makers’ laboratories have resulted in the availability of very bright, firmly-adhering metallic gravures which work well on the machine.
As is well known, there are two main types of overprinting varnishes, one containing a proportion of volatile liquid such as methylated spirit or turpentine, and the other composed entirely of non-volatile ingredients. Although the former type is excellent as far as it goes, it is probable that it will be increasingly displaced by the non-volatile varnishes. These latter are easy of application, being printable in much the same way as ordinary letterpress inks; they can also be safely used to overprint many colours which would bleed in a methylated spirit varnish.
Research has been in the direction of increasing the gloss and improving the working qualities of the overprinting varnish. Some modern preparations are quite soft and easily workable, and yield a hard, smooth film of extremely high gloss, not only when applied to a dry non-absorbent ink layer, but also when printed directly on to the paper. Coloured overprinting varnishes are also available.
For some purposes, particularly for printing on food wrappers, it is sometimes advisable to use an ink having as little odour as possible. Varnishes made in the ordinary way possess a slight smell which is imparted to inks made from them.
There are two methods of producing an ink which does not possess the smell of ordinary varnish. Either there can be incorporated with the ink a small quantity of a perfume which satisfactorily masks the other smells, or odourless varnishes (made by special processes) can be used. Both methods can be combined.
Improvements in offset and litho inks have included the increasing of the water resistance and the strength of colour. For—good quality offset work, particularly where in competition with photogravure processes, great colour intensity of the ink is, of course, highly desirable, since the film of ink in the offset print is so thin.
One type of modern offset ink contains special water-insoluble dyestuffs in addition to the usual pigments, a device which results in great colour strength and quite satisfactory resistance to water.
A variety of good ink removers have been in use for a long time and are well known, but a point of which many are unaware is that there are special removers for dry ink. A roller or type face which contains patches of dry ink will require a considerable amount of laborious scrubbing with an ordinary ink remover before it is clean, but with special solvents or solvent mixtures, it is only necessary to moisten the surface. After a few minutes the powerful action of the solvent uproots the dry film. Sometimes it may be preferable to remove the worst of the dry film with the special solvent and then to finish off with an ordinary ink remover. In this way, the cleaning of dry ink can be done in a tenth of the time usually employed. Of course, the solvent does not injure the roller or type face in any way.
With regard to the cleaning of ordinary aniline inks from the machine, methylated spirit is the standard medium for this purpose. The best anilines do not dry on the rollers too quickly, but if the rollers or other parts have been left inky overnight, it may be desirable to wet the surface with a special aniline ink remover before finishing off the cleaning with methylated spirit.
This article from the British Printer, 1934 and written by J. D. Cohen, BSc, AIC
The developments that made high-speed printing possible
Printers’ rollers have occupied the greatest printing minds since the early 1800s. While the rotary letterpress machine should have improved production speeds, their potential was held back by the lack of rollers: just how could ink be transferred to the forme with speed and consistency? This article looks at early rollers, composition rollers and rubber rollers.
When using the original hand presses, printers used ink balls. A wooden handle and sheepskin bag filled with horsehair formed the ink ball, and these were used in pairs. The inker could ‘mill’ the ink between the balls and then apply ink to the forme before printing. This approach was used between in invention of the press and 1790, some 340 years.
With the introduction of the rotary press, printers simply modified their existing technology and built wooden rollers with a sheepskin cover filled with horsehair. While made with some precision, they could not coat the type effectively, and left a mark on the page where the stitching in the sheepskin cover did not transfer ink.
In 1818, Robert Harrild developed the first ‘composition roller’, made of glue (from calfskins) and treacle — his development was based on the process used by the Staffordshire Potteries to add patterns to pottery. While this mixture was tacky enough to carry and transfer ink, the ingredients led to an instability of the roller. The glue gives up water in dry atmospheres and shrinks and cracks. In damper conditions, the glue takes up moisture and the roller swells. Thomas de la Rue added glycerol (US: glycerine) to that original mix. Glycerol has a tendency to absorb moisture from the air and this balanced to a degree the effects on glue to produce a more stable roller. Rollers still had to be made to suit the atmospheric conditions and seasons — so rollers were made to different recipes in different parts of the world, and depending on whether it was summer or winter.
Just as printers were expected to make their own inks, they were also expected to be able to cast their own rollers. Presses (like the Arab) were supplied with roller cores (the central metal bar) and moulds for the composition. Printers would routinely melt down and re-cast composition rollers. A big problem was to prevent air bubbles from sitting on the edges of the roller, and causing small marks that transferred to the inked forme.
Commercial makers of composition rollers used a gatling gun to hold multiple moulds and pour composition mixture into all of them at one time.
Adana recommended four sets of rollers: two pairs of rollers each for summer and winter; one for colour work (including white) and one for black. Rollers would be used for colour first and then black. Rollers should be carefully cleaned and covered before storage using oil or petroleum jelly. An appropriate mix would be 10% medical paraffin plus ‘suffers grease’ (an engineers’ jelly).
Where to get hold of your letterpress needs
There are a reasonable number of suppliers for your letterpress needs. This limited list is based on personal recommendations. Please contact me if you want to recommend a supplier or want to be added. The Letterpress Alive site provides a more comprehensive list of current suppliers.
Dave Kearley at DD Metal Products in Bishop’s Stortford make metal letterpress supplies including new quoin keys, composing sticks and tympan bars, plus offer serviced and cleaned quoins.
Tony Wood, Leeds: 0113 260 6134 — http://www.impression-works.co.uk/
Rollers for common hand presses are available from a number of UK sources. Try Adana’s parent company — Caslon.
Gemini Printers’ Supplies offer a comprehensive catalogue of different papers, and also supply letterpress inks and some other sundries.
Mr Julius Stafford-Baker, a great letterpress advocate and hands-on helper, has launched the first 21st Century store selling 19th Century equipment with his Composing Room Stores. You can order many of the requsites of the letterpress printer from him — furniture and leading, packing and quoins. You can also hire single words (properly ‘sorts’) from him in fancy types.
Patrick Roe runs a Monotype operation; a letterpress printing works; and also a service to move and restore machinery! Have a look at http://www.theloganpress.co.uk for details.
Alderson & CO Limited specialise in all things letterpress. Full Restoration, Sales, Service, Breakdown and Relocation of all Letterpress Machinery. Contact Neil Alderson on 07834045453 or firstname.lastname@example.org.
Caslon, Adana’s parent company, are again producing Adana machines and all the associated equipment and supplies.
France-based supplier of renovated Adana machines. http://adanashop.info/