A cylinder coated with composition, fixed in an iron frame, and revolving upon an iron rod running through it, with which to ink the forms, preparatory to taking an impression.
The roller has almost entirely superseded the use of balls in printing; and, since the introduction of composition, I may venture to say it has completely superseded the use of pelts for balls. See Pelts.
The use of the roller is less laborious to the pressman than balls; and for common work, and indeed all work where weak ink is used, it coats the surface of the types, &c. more uniformly, perhaps, than balls; but for fine work, where strong ink must be used, and really fine work cannot be produced without strong ink, the roller is decidedly inferior to the ball, partly owing to the difficulty of taking ink and distributing it on the inking table; and partly owing to the inferiority of rolling to beating with balls, in coating the surface of the types with strong ink.
The introduction of composition in lieu of pelts has been the cause of a complete change in printing; but for this article, machine or cylindrical printing would never have been accomplished, as all the first attempts were made with skins to coat the roller, and all failed, owing to the imperfection of joining the edges; it was this that baffled Nicholson, who died before its introduction; and it was the introduction of this article that enabled König to avail himself of Nicholson's invention and to reduce it to practice, after he had failed in his project of applying steam to the working of presses.
The composition was first introduced in printing by Mr. B. Foster, who spread it in a melted state on canvass, and then formed it into balls in the usual manner. I have been informed that Mr. Foster obtained his knowledge of its properties from a cotton manufactory, where it was used in some part of the machinery; but Mr. T. C. Hansard says that it was in the Staffordshire potteries, in which they use what are there called dabbers, that Mr. Foster first observed it.
Composition. — Mr. Hansard, a printer of extensive practice, in his Typographia, says, “The composition consists principally of glue and molasses, or treacle. I have seen various receipts of ingredients and proportions, some possessing the recommendations which distinguish the recipes of ancient physicians; namely, a vast variety of articles with counteracting properties. But the simple prescription which my experience has proved best, is, to provide glue of the finest quality, made from the cuttings of parchment or vellum; fine green molasses, pure from the sugar refiner, at least not adulterated for the bakers' or grocers' shops; and a small quantity of the substance called Paris-white [carbonate of barytes], and you will have every ingredient requisite for the compo. The proportions have been so variously stated, and so different from what I have found to be eligible, that I am wholly at a loss to account for such differences.
|One receipt which now lies before me in print, says||2||1|
I find a mixture of 2 / 6 or 2 / 7 and about half a pound of the Paris-white, will make the compo of a superior quality to any other proportions, and will be sufficient for two demy rollers. The great disparity which appears in these receipts may perhaps be attributed to a difference in the quality of the materials, and to the mode of management.” Thus far Mr. Hansard on the component parts of the composition.
The late Mr. Robert Branston, an eminent engraver on wood, and who was also very skilful in printing his productions in a superior manner, told me that he made his balls of glue, treacle, and a little shoemakers wax, and that they answered as well as Foster's. The Cave of Despair, in my Practical Hints on Decorative Printing, will serve as a specimen of his abilities in both these departments.
An ingenious printer in the country, and a good workman, sent me the following receipt, from which he used to make balls for his own use: — Take a pound and a half of glue, let it soak in cold water twelve hours, boil it without any additional water; when it is hot add half a pound of treacle, half an ounce of turpentine, and a quarter of a pound of tar; this quantity is sufficient for a pair of balls. Prepare your canvass or coarse cloth of the size the balls are wanted, by rubbing on it bees wax, (or common paste will answer the purpose after it has been allowed to dry,) to prevent the composition running through the pores; when the mixture is nearly cold, pour it on the canvass, held in a concave manner, in order that it may be the thickest in the middle, and thinner at the edges; then knock up the balls in the usual way.
Another receipt, from which a large establishment in London made their balls and rollers, and the latter both for their machines and presses, is equal parts of glue and treacle; but as the composition is affected by the state of the atmosphere, it is found by experience that in cold weather a greater proportion of treacle is required, and in warm weather a greater proportion of glue.
This establishment was of opinion that the glue known by the name of London Glue is the strongest and best.
These different receipts, each of which was held in high estimations by the party who made use of it on account of its individual superiority over others, tend to show that different proportions of the same materials with different ingredients incorporated with the mixture, produce a composition that possesses all the requisite qualities.
Casting Rollers. — Mr. Hansard gives the following directions: — “ The cylinder upon which the compo is cast is made of alder-wood, turned to a requisite diameter, so that the coat of compo which it receives is half an inch. The cylinder is perforated through its centre, having a brass bush or collar driven into each end, through which is passed an iron rod, as an axis, with an enlarged head at one end, and tapped with a screw at the other.
“It is necessary to procure a mould very accurately made and well finished. Mine is made of brass, in two parts, adjusted to each other with rebates, the inside being finely turned and polished, and having flanches projecting by which the parts are screwed together by the screw and lock-burr. To each end is also fitted a collar; and a circular plate of iron is accommodated with great precision to the bore of the mould, having a projection in its centre to enter a cylinder of wood about which the compo is to attach itself, and to hold it exactly in the centre of the mould, and the other end of which is kept in a corresponding position by means of a brass piece to allow of the compo passing down between the interior surface of the mould and the wooden cylinder. There are little projections on the sides of the mould, which serve as feet to support each half in a steady position while lying upon a table or elsewhere. Previous to joining, the parts of the mould must be nicely cleaned and oiled, and the greatest care taken that no particle of compo, grit, or dirt, remain in the rebate. The parts being carefully placed on each other, and the wooden cylinder fixed inside, the screws must be put into their respective places in the flanches, and when all is properly made tight the mould is to be set upright for receiving the compo.
“The next material part of the apparatus is the melting kettle. This must be a double vessel like a glue-kettle, so that the compo in the interior may be melted by the heat of the boiling water in the exterior. For this purpose a strong boiler may be the best or readiest thing found, into which let a tin vessel be fitted, with a flanch to rest on the rim, so as to leave one or two inches clear under it. This vessel may be six or eight inches above the top of the boiler, so that the lid of the one may fit the other; and it must have a handle on each side; also a large lip for pouring out the compo.
“Being thus prepared, put the glue into a little water for a few hours to soak. Pour off all the liquid, and put the glue into the inner vessel, the boiler having in it as much water as it will contain when the inner vessel is in its place. Put it on the fire, and boil the water as quick as you please, the heat of which will soon cause the glue to dissolve, and evaporate part of the water. When the glue is all melted, add the molasses, and let them be well incorporated together for at least an hour, receiving heat from the boiling water, which is an uniform degree that cannot exceed 212° of Fahrenheit. Then with a very fine sieve, mix the white powder, frequently stirring the compo. In another hour, or less, it will be fit to pour off; and when it is, take the inner vessel out of the boiler, and pour the mixture gently into the mould through the opened brass keeper. In about an hour, if the weather be dry and favourable you may take the roller out of the mould; hang it in a cool, dry, situation, or lay it horizontally in a rack made for the purpose, and the next day it will be sufficiently hardened for use. As there will be rather more of the compo at each end of the cylinder than would work clear of the frame in which it is to revolve, cut off from each extremity about half an inch, by encircling it with a piece of fine twine.”
There is a serious practical disadvantage in the mould being formed of two pieces; that of having a seam or ridge running the whole length on both sides of the roller. This seam prevents that accurate distribution of the ink which is essentially necessary, and increases the probability and danger of producing monks in the impression, which ought to be avoided as much as possible, as destructive to good printing.
I have at different times heard complaints of the difficulty of drawing the roller out of the mould, and of the injury it frequently receives from the surface being damaged, which spoils it, and makes it necessary to be recast. This accident occasions disappointment and loss of time; as cleaning the mould from the composition which adheres to it when this happens is tedious. I attribute this to the mould being made too thin, which expands when the hot mixture is poured into it, and contracts as the mixture cools, thus becoming, by the contraction, too small for the roller, and binding it so tight as to prevent its being drawn out with facility, and without great risk of injury.
I know one house in the Metropolis that makes rollers in the most perfect manner, and experiences little or no trouble in drawing them from the mould; and I know a person who had a mould made, with the same result. These moulds were made out of a solid cylinder of metal (tin, or type metal is equally good for the purpose, and more durable), the aperture bored to the size of the required roller, and carefully polished on the inside, the tube being thick, in some instances two inches, so that it was not much affected by the heat of the composition, the expansion being very trifling, and of course the contraction small in proportion; so that the roller when cold was not compressed by the mould, or so slightly as not to cause any inconvenience or damage to it in drawing out. The inside of the mould should be carefully wiped out before using, so as to be perfectly free from dust or dirt, and slightly oiled, which causes the roller to quit it more readily.
Preservation. — Mr. Hansard says, “To keep the rollers in good condition for working, a place should be chosen where the air has free circulation, without being subject to the extreme heat of the sun in Summer, or the freezing damp air in winter; in short, in as even a temperature as possible. It will be necessary to keep a stock of more rollers than are at work; as it is frequently found, when a roller is sick, or greasy, or soft, or you do not know what is its ailment, that washing it clean, and hanging it to rest for a time, restores it to as good a state as ever.
“One other circumstance must be noticed, namely, the influence of the variable temperatures of different situations on this composition. This I have had particular opportunities of knowing, from having carried on business in two distant offices. It frequently happened that when the compo was working kindly at one office, nothing could be more teazing than its progress at the other. Indeed, while I was supplied by those who make for the trade, one of my houses frequently gave them a great deal of trouble. I have heard both Foster and Harrild say, 'that they were obliged to make a harder compo on purpose for my house and one or two others similarly situated, than the customary temper of the mixture:' and, frequently, the only alternative was, to find me a roller that had got hard and useless at some other house, to suit the low temperature of mine. The difference was this — one of my houses had the press-room on the ground-floor, the joists and flooring lying on the earth; the sink room adjoining; wet sheets hanging very low; very little influence from the sun, and no thorough ventilation; consequently, from the humidity of the atmosphere engendered by these circumstances, it was a constant complaint that the compo was too soft. At my other house the press-room was on the two-pair floor; the poles very high; the sun's rays had free admittance, and the ventilation was very complete. Here the compo, complained of as too soft at the former house, was all that could be wished: hence it became the roller-nursery; and by sending them to hang up a day or two, when out of order at the other place, they became firm and fit for work.”
From this statement it appears that any fixed proportions of the materials for the composition cannot answer generally, and that they must vary according to circumstances. And it may cause us to cease wondering at the number of recipes, and of the different proportions of the various articles, and at being told that they all answered very well; for it is evidently owing to the situation, whether moist or dry, of the press-room of a printing office, that different proportions of ingredients are requisite to make a roller work well, under different circumstances.
The usual method of keeping rollers in working condition is to cover them at night, and when they are not likely to be wanted for some time, with a coating of common or refuse ink; this does not dry, and prevents evaporation, and thus keeps them in working condition: the ink must be scraped off when they are required for use. A roller will get foul in the course of working, or become too hard, it should then be washed well with lye and the lye brush, which will remove the foulness, and it may be further washed with clean water and the hand to remove the lye, and to give it a clean surface; it would then be necessary to distribute it well on a clean table. It would be now advisable to proceed with the presswork with a fresh roller, and allow the one that was washed to have a rest, which generally improves its working condition. If a roller become, too hard, and the surface is clean, then washing it with clean water and the hand, distributing it on a clean table, and placing it in a damp situation, will restore it; in fact, when the pressroom is dry and well ventilated, keeping the rollers in a damp situation when not in use is preferable, in my opinion, to softening them with water, as the moisture is gradually imbibed by the composition, and makes it more uniformly soft and kind.
When rollers get too soft, the general practice is to hang them up in a current of cool dry air, which evaporates the superabundant moisture, cools the composition if the room has been too warm, and brings them to a good working state. But a more expeditious and effective method, is to sponge them with spirit of turpentine, which restores them to a proper condition sooner than any other method, and also cleans them more effectually than lye. If the same rollers are required to be used when it is necessary to change the colour of the ink, there is not any article that will clean them so expeditiously, and take the ink which had been used out of them so completely, as spirit of turpentine.
Occasionally the pressman finds that he cannot produce good and clear impressions with all the care and attention that he can bestow upon his work, and this when his roller seems to be in good condition, and no apparent cause can be assigned for the deficiency of quality; the roller is then said to be sick, or tired; and the only remedy that has yet answered to remove this inconvenience is to give the roller rest; that is, to hang it up, and take another roller for the work in hand; after resting for some time, it will be found that the sick or tired roller has resumed its original qualities, and will again produce good work.
Rollers, when not in use, should always be hung up in a shady place, which is generally done by one end of the frame, for if left on the inking table they would stick to it, and the composition would be torn in the act of separation; neither should they be exposed to the action of the rays of the sun in summer, which will soften the composition so much as to cause it to run, and thus spoil the roller. These observations apply equally to composition balls.
The following is an abstract of the French method of making and treating rollers.
The French roller-makers proportions are eight pounds of glue and twelve pounds of treacle, which is sufficient for four rollers used at press; the quantity required for those used at machines will vary according to their length and diameter.
Paris made glue is the best: it ought to be transparent, have little colour, and break like glass. Flexibility in glue is a proof of its weakness; and it is injured by being left in a damp place.
The treacle ought to be pure; the most compact is the best. To avoid being deceived, it is best to buy the refined. The old is weak, and not of a good quality for rollers.
In preparing to make four rollers, two pounds of good glue must be soaked in river water; the strength of the glue must determine how long; but if too long the glue loses its strength, and the rollers are injured.
This portion of the glue, thus soaked, is then put into the melting kettle, and placed over a fire, and stirred with a spatula; and when it is quite melted, the rest of the glue is added in similar portions, till the whole eight pounds are melted, which ought to have, an hour's boiling before adding the twelve pounds of treacle. The treacle is then gently poured into the melted glue, stirring them until they are well incorporated. This done, they, are left over a moderate fire for an hour, stirring them with a spatula every ten minutes. The surface must be skimmed, and afterwards the vessel must be left a little time to slightly cool, before being poured into the mould.
The cylindrical tube in which the rollers are cast should be smeared in the inside with a brush with oil; neatsfoot oil is the best; and it is necessary that every part should be carefully oiled, and that the wooden cylinder should be well cleaned and free from moisture.
These observations can only apply generally to the making of rollers; it is practice which can alone furnish the particulars. The temperature varying in each season must be the object of special attention, as it renders the materials more or less flexible, and requires the composition to be more or less boiled.
It is a fault with rollers when they lug too much, as it detaches the composition from the wooden cylinder. When they are moist they should not be too much washed, as that also tends to make them lug, and detaches the composition. If they are used too soon after making, they distribute the ink badly, fill up the letters, and last but a very little time. They ought to be exposed to a current of air to dry them, and to be carefully scraped before being used, and again afterwards. If they are too dry they must be sponged all over and distributed upon the table until the water has disappeared, and then on a clean table, before taking ink. When they begin to grow old and hard by work, they must be washed in proper lye without being rinsed in water, and care and attention given to their wiping; and by these means they may be preserved for a considerable time. Rollers, when not in use, should be suspended in a place neither too dry nor too damp.
Recasting. — Before recasting old rollers, take great care to wash them well with lye, in order to detach the ink with which they are coated: if they are dry they must be scraped with a knife, as grease deteriorates the matter. Afterwards cut the composition all over with a knife, and it will then be easily detached from the wood. If it is new it will not need cutting, it will easily dissolve; if old it must be cut into little pieces, that it may dissolve more easily, and with less loss: if the composition is very strong, the little pieces must be washed in a pail of water, warm water is better than cold; add to it two pounds of treacle, for four rollers. and so in proportion: when the matter draws out well in threads, the composition is good.
If the rollers have been recast many times, and they draw too much, they may be recast without adding fresh treacle or glue. Rollers which are recast are better than new; they are more elastic and less melting. With three pounds of glue, five pounds of treacle, and the matter of three old rollers, four rollers can be made; if a small glass of spirits of wine be added it will facilitate the dissolving.
The rollers fail the most frequently at the ends. They ought to be dry, and clear from grease. It is a good plan before using them to scrape them clean, and to sponge the ends for about an inch and a half with spirits of wine, and to leave them to dry; the gelatine draws better.