A Treatise on Calico Printing, VOL. I-II
Printed for C. O'Brien, Bookseller, Islington, and fold by Bew, Paternoster-row: Richardson, Royal Exchange: Murray, Fleet-Street: And the Booksellers of Manchester, Glasgow, Dublin, &c.
1792Cross-backed blocks, if they must be used, are most proper for prints, but particularly for prints that have much work, and that have grounds to them not very easy to be hit in; and the firmer the backs are fixed to each other, the better; in order to render them as little liable to warp as possible; for the evenness of the face of the print being of the utmost consequence to preserve, no consideration should be spared to at tain so desireable an object. The grounds how ever should be on single back blocks, that they may occasionally be made round or hollow, to suit the contracting or spreading of the face of the print. An objection notwithstanding lies here in the case of prints that have the work close and solid; as they cannot be taken off too wide, on account of the quantity of colour which they carry, causing the cloth, if soft, to dilate so much, that the grounds are generally too narrow although the print is brought hollow perhaps in order to work it. In these instances, probably single backed blocks may be best, it being difficult, if net impossible sometimes, to force cross-backed blocks round; and to swell them by soaking, lays a foundation for their being always out of order; indeed if the blocks for the grounds could be taken off proportionably hollow, and very dry, and made true, or rather round when they went to work, it might answer the same purpose. This inconvenience however does not happen when the cloth is permitted to get very dry, as then the quantity of colour causes it to contract; but in this case, if too much contracted, the laying of it some time in a rather damp place, will cause it to give out again.
This object of rendering prints and grounds fit for each other, and the keeping of them in that state, is, in the process of printing, of the first consequence, and (as before intimated) cannot be too much attended; as the immediate and certain effect of their not agreeing, or of the prints getting out of order, is the delay of the work; and the endeavouring to remedy it, by putting the face en another back, rarely answers the purpose, especially if it gets into an unskilful printer's hands. For, among other circumstances, a great number of screws are usually put in, which, beside twisting the wood of them selves, the printer is continually tightening or loosening some of them, or forcing in wedges of some kind, soaking one end, then the other, and so on, till at last, the print is rendered entirely useless, and the pattern is stopped from going on with, perhaps, only a piece or two printed; and as it may be too late to cut it over again, the misfortune is aggravated, as the expectation of gain from the working of it is at an end.
The firmer crossed backs can be united with out screws (for screws frequently force up the faces) there will be the greater probability of their standing; and if, for the conveniency of having span holes, a back is let in, the screws should stand quite across, or in squares; and it should by no means be so tight as to affect the print endways; therefore it seems more proper to let the grain of the back which is let in, be the same way as that of the upper hack, whether it be thinner or thicker than that next to the veneer; for it may be reasonably supposed, that, if the upper back is nearly cut through in the middle, to let in a small one, it will lose much of its power to resist the warping of the back which joins to the veneer; and much less of its power will be lost if the upper back be cut quite across, as well as quite through to the other back; for from that circumstance, together with forcing the moveable back tight, the probability of the print casting endways, is aggravated to a certainty.
Another reason for endeavouring to fix prints to an uniform state is, that when single backed prints get very round, dove tails are generally let in very tightly, in order to check that tendency; the consequence of which is, that the back rarely sails of being split, especially if not eased at proper times, or otherwise carefully attended to.
But after all, from the circumstance of not being able to know at first, whether crossed backs are of equal qualities, or as they should be in other respects, found single oak backs seem preferable for general use, as not laying under the dis advantage attending crossed backs; which is the great difficulty, if not impossibility, to warp them as you wish; or if once warped, to get them true again at pleasure.
To keep some particular prints true by force, if force be necessary, a strait piece of iron, rather thin, and of a breadth answerable to the thick ness of the block, might be firmly bound round as a fillet, and answer that purpose; especially if, to such a check, two pieces are annexed to the sides into which the back is slid.
The crested backs of blocks, perhaps should be either all of deal; or all of oak, because if one back is of oak, and the oak back is next to the veneer, that circumstance tends to throw the print hollow endways; neither the veneer nor the deal having strength sufficient to resist the casting of the oak; for it may here be observed, and proper use may be made of the remark, that though oak is harder than deal, yet deal has an advantage over, oak, in not imbibing water so - readily, and of course, not being so likely to cast by damping or wetting; but then, as a counter- balance, heat will sooner affect it.
It may likewise be here observed, of those trees growing where the fun does not affect them all, round, that one side of them is softer than the other, the same as wood is softer or harder the nearer or farther it is fiom what carpenters call the sap; to which cause, among many others, oftentimes not to be accounted for, is the aptitude of some blocks to warp this or that way, in spite of every endeavour to, bring them to the state desired, or to keep them in that state; from which consideration, when it is evident which way blocks are naturally inclined to be, and they have remained in a proper place long in that state, whether round or hollow, or whether that tendency is in the backs, or faces, they had better be brought to the state you desire, by plaining, rather than by heat or wetting them; else theconsequence would be, their getting into their foraer state, as soon as left at liberty. But if their tendency to warp any particular way is exhausted, a second plaining cannot be properly recommended.
Blocks should be kept in a rather dry place, without a fire, at a convenient distance from the ground: those intended for prints seem to require laying with their faces downwards, and thole for grounds with their faces upwards, prints in general requiring rather a round state than otherwise, and grounds the contrary. And for convfcniency the different sorts should be kept together, but, if conveniency only is considered, the best situation for blocks to be placed is on their sides, in proper ranges on shelves one above another, so that one can be drawn out without displacing the rest, which is ever the case when they stand piled one above the other.
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