If the flong is very soft, the beating must not be continued until these divisions are so distinct as with normal flong, and if the flong is very hard one will only obtain sufficient relief by making the divisions show very clearly.
The progress of the 'beating may always be seen by steadying the monld with one hand and turning back one corner, and the flong should always be so soft that this can be done without straining or stretching the part turned over. Where there are extensive whites in the forme, the mould will be arched downwards, and some support is needed in such places, or the arched parts would crnsh down by the weight of metal in the casting-box, and much metal would have to he cut away from the plate. The usual way is to paste the back of the flung, and to lay in the deep parts a few pieces of paste-board or of old mould, after which a second sheet of brown paper is pasted and laid over all. A very gentle beating is now given to the mould, care being taken not to beat this last paper down into the hollows, as the main use of this sheet is to siring or tie the domes and hollows formed in the main part of the flong.
The impression is now sharpened up by planing. The printer's planer - which is a slab of hard wood - is placed on the mould and struck several times with a mallet. This should be repeated several times, moving the planer be-tween-times, and care must be taken not to shift or strain the mould sideways. Two or three thicknesses of blanket, or still better, enough blotting paper to make up about 1/2 in. thick, being placed over the mould, the forme and mould are pinched up in the drying press (Fig. 297).
A few words more about the beating brush. If the face is not level, or should become unlevel by use, it may be burned flat by contact with a plate of iron heated to a dull redness, and by the same means the edge and corners farthest from the handle may be very slightly sloped off, thus making it more easy to give local treatment to any special part of the mould. Workmen who-'have skill and confidence in the use of the brush may strike tolerably hard, and they often find it a convenience to load the brush by fastening a plate of lead to the back. Some of the Continental workmen, instead of using a brush, prefer to use a wooden blank provided with a handle and covered with several thicknesses of cloth or "moleskin." Then, again, a rolling machine, or a vertical press, is occasionally used in making the mould, but the press and rolling machine are of little use except in the case of tolerably solid and uniform formes, such as the pages of a newspaper. The rolling machine for moulding consists merely of a moving bed with an adjustable cylinder over it, bed and cylinder being geared together. The machine, however, is seldom used without the brush being used as an adjunct.
Sometimes the press or machine is used to set the flong firmly in position on the type, the brush being used for finishing; and sometimes the brush is used first, and the machine is employed to sharpen up the impression, to do what the planer does in the process of making a mould by hand.
A sufficient drying of the mould may be effected in as short a time as 3-4 minutes, in which case the heat is urged almost to the softening point of the type, or the heat may be more moderate, so that the drying takes as much as 1/2 hour. It may, however, be taken that in the case of ordinary commercial stereotyping some water is invariably left in the mould; many hours baking at a temperature of 200° C. being necessary for the removal of the last traces of moisture. So that, when the best possible results are required, it is desirable to considerably extend the time allowed for drying.
In ordinary cases - the work not being subject to the extreme need of haste which exists in the case of newspaper stereotyping - the forme will remain in the drying press for 10-15 minutes, during which time the blanket (or covering of blotting paper, as the case may be) may have been changed 2 or 3 times; or if this is not done, the press should be undone, and the covering turned over to allow the more ready escape of moisture. All this time the bed of the press may be conveniently heated to a temperature of 100°-130°C. the former being about the degree of heat obtained if the bed forms the top of a steam-chest fed with waste or " exhaust " steam; but if " live " steam of about 30 lb. pressure is used, the temperature will be something like 130° C.
To return to the forme and mould. The mould leaves the forme at once. When any adhesion occurs, something is wrong with the work, e.g., tissue paper not impervious; excess of paste under tissue paper, thus breaking up tissue; tissue broken in beating, from too hard blows or extreme softness of flong; mould too deep, so as to fit over the shanks of the types, or even penetrating between them; paste on face of the flong, from careless making or piling; imperfect oiling of forme, or unsuitable oil; alkali or other foreign matter on type.
But a slight tendency to adhere can generally be combated by repeatedly lifting the edges of the mould, as far as is possible without bending or straining the mould; and then letting it spring back; at the same time slightly loosening the quoins and beating the back of the mould with the brush. (Fig. 298).
In the case of persistent sticking, the only alternative is to heat the forme once more and repeatedly moisten the back of the mould with water. In this case the mould will be spoiled.
The mould, as it comes off the forme, is dry to the touch, but ordinarily not dry enough to give a good cast, and before drying it further it is convenient to trim the edges to the outsides of the gutters left by the clumps; and to paste on to one end a flap of brown paper long enough to project 2 in. or so out of the casting-box, and, at the same time, to allow a head of metal of not less than 6 in. For this purpose, a more adhesive paste is required than that used for making the flong. Stiff rye flour paste is best.