Electrotyping
A process which has recently come into use in place of stereotyping, to which it is superior in two ways, especially for woodcuts or newspaper headings. The copy or plate being of copper, and therefore much harder than the type metal, long numbers can be more profitably and clearly produced; and the strokes being finer, and the sunk parts deeper, the impression from an electrotype more nearly approaches one from the type or engraving itself.
The art of plating by electricity was invented almost simultaneously by Spencer, of Liverpool, and Professor Jacobi, of St. Petersburg, in 1837; made public by the latter, October 5, 1838, and by the former, September 12, 1839. Murray applied blacklead to non-metallic bodies as a conducting surface in January, 1840, and in the following April the first specimen of printing from an electrotype appeared in a London periodical.
For an account of the chemical processes involved, we must refer the reader to any elementary book on the subject of electro-metallurgy, as well as for a description of the utensils employed, such as the battery and the depositing trough; the metals, solutions, &c., are the same as those used in various trades which have utilized electricity in this manner.
What we propose to do is to show their special adaptation to the process of obtaining copper casts of type formes, and the system of preparing these for the press. Smee’s battery is the most preferable for this purpose.
The mechanical part of the process now familiarly known as electrotyping, consists of Moulding, Backing-in the Plates, and Finishing. Mouldings may be made from woodcuts. The most effectual moulding substance is the best yellow wax, to which two to fifteen per cent. of turpentine may be added in cold water to prevent it from cracking whilst cooking. New wax should be boiled several hours before moulding. It should be kept in a large iron fish-kettle, to be ladled out as required. Should it become burnt, it is useless.
To prepare woodcuts for moulding, lock up the woodcut in a chase with a type-high bevelled metal clump border all round it. Brush the cut over sparingly with turpentine to remove the printing ink which remains on the block from the taking off of proofs. Should the cut be an old one, and the fine lines much clogged up, which the turpentine fails to remove, it is better to brush the cuts with a hard tooth-brush, dipped in liquor potassæ. The type-high clumps prevent the wax from spreading, and the fac simile of them forming an outside border to the shell, becomes a barrier to the metal, retarding it from getting to the face of the shell during the process of backing; it also forms a wall for the dogs of the lathe to bite firmly to while the back of the plate is being turned. A wooden straight-edge should now be placed across the forme to see if the cut is of the same height as the clumps; if not, the cut must be underlaid—for it is desirable that the cut should be a trifle higher than the clumps.
Let the cut now stand until it is perfectly dry, then proceed to backlead the forme by placing it in the blackleading try, and well brush it over with the blacklead, taking care that the cut be well bronzed over, and that no particles of the lead be left in any of the fine lines of the engraving. The blacklead should be free from all adulteration.
To prepare a type forme for moulding, surround it with the bevelled type-high clumps, placing the bevelled side against the type. When locked up and planed down perfectly even, lay the forme on a board, and take it to a trough containing clean water; next mix plaster of Paris and clean water to the consistency of cream, then pour the mixture over the forme, well plastering it with the hand into the lines and spaces. Let the forme rest till the plaster begins to set, then, with a piece of reglet, scrape off the plaster level with the face of the letter, and with a water-brush wash out the plaster to the depth required, which should be to about the shoulder of the type. This process is exactly similar to the first in the plaster system of stereotyping.
Well sluice the forme at the back as well as the face, and stand it on end in the forme-rack to drain for an hour or so. After observing that the forme is tightly locked up, plane it again, so as to not crack the plaster, and see that the face of the forme is even; take it to the blacklead trough, and well bronze it all over, as described for woodcuts, taking care that the forme is dry and free from moisture. It is now ready for being moulded.
The moulding tray should be something in the shape of the forme to be moulded; it may be made of stereotyping metal. In appearance it resembles a shallow printers’ galley, but surrounded on all four sides; about a Pica or an English in depth. Two pieces of stout copper wire are soldered on to the edge in such a manner that it may be suspended in the depositing trough. Warm the moulding tray a little, lay it on a flat table, perfectly level, and with a tin ladle, pour out the wax into the tray in a continuous stream, with a slow, steady, rotary motion, within an inch or so of the sides of the moulding tray. Let the wax set all over, and then brush over the surface with plenty of blacklead, laying it on with a soft hat-brush. The sooner the blacklead is applied to the surface of the wax, without disturbing the wax or marking the surface with the hairs of the brush, the better will be the mould, as more blacklead will be held on the surface.
The forme or woodcut must be moulded while the wax is yet warm; but it must be perfectly set. The temperature of the room in which this important process is performed must be maintained at summer-heat. The wax, in cooling, ought to present a smooth and even surface. The moulding press may be either (for small jobs) a copying press or a stereotype moulding press; the higher the temperature at which the wax is moulded the less pressure required.
Now place the forme exactly under the centre of the plaster, with the moulding tray containing the slightly-warm wax upon it. The amount of pressure requisite to displace the wax must be learned by experience: too shallow an impression causes a deal of work for the building knife, and an unnecessary depth of dip may result in damage to the mould in delivery.
To deliver the mould from the forme a pair of lifters is wanted, although a thin screwdriver may be used. Insert the lifters between the furniture of the forme and the edge of the moulding tray at the top and bottom of the page, and gently, with a steady hand, apply leverage gradually until the mould is relieved from the mould or woodcut. Should the mould not be a good one, melt the wax and commence again. Never lift a mould from the sides of the form, or damage will result to the raised excrescences of the mould, which are to form the counters in the plate.
The building knife is made of copper. It is half knife and half spoon. Have close at hand a small cauldron of melted wax, and a gas jet by which to warm the building knife. Draw the knife along the projections that are to be raised still higher, and the wax will follow. The object of this is, that where paragraphs or open work occur, the parts can be lowered, to obviate the necessity of chiselling the plates, as in stereotyping. The building knife can be heated by dipping it in molten metal, and the building can be done by holding the hot knife in one hand, and a stick of hard dry wax in the other, feeding the building knife as you go along the spaces between the lines.
The mould having been finished and pronounced satisfactory, blacklead it all over, filling all its interstices and brushing the blacklead well in. Now brush all the particles of the latter, except what is bronzed on by the badger’s hair brush. If the mould be held in the light, at a certain angle, the operator may descern whether even the finest lines are highly polished. If any line or letter appears dull, the blacklead is not sufficiently blown or brushed out of such parts. To prepare the blacklead mould for immersion into the depositing trough, paint the back and sides, and also the edges of the moulding tray, leaving a spot here and there all round for the copper deposit to start from. These spots may be slightly scraped bright, to facilitate the deposit of the copper, which will shoot out from these spots towards the centre of the blackleaded surface, gradually covering it.
As soon as it is placed in the depositing trough containing the copper solution, the moulding tray containing the mould must be hung to the brass rod of the depositing trough with brass S hooks. The connections must be all clean and bright. The connection of the battery having been made, and the copper plate to be reduced placed in its proper position, the current of electricity being complete, submerge the mould in the sulphate of copper solution, hang on to the S hooks, and see that the whole of the moulding frame is under the solution, where it can remain until the deposit is sufficient to enable you to judge if all is going well. Should the copper deposit in places where it is not required, the spot must be dried, and the place stopped out with hot wax. The time usually occupied to deposit thick enough for ordinary purposes is twenty-four hours; but this must be regulated by judgment. To prevent air bubbles forming on the face of the mould, take it out of the trough and dip it in diluted methylated spirit (half spirit and half water).
The copper being deposited of the required thickness, proceed to disengage the shell from the wax by placing the mould with its back on an inclined board; then pour boiling water over the shell, gradually lifting it at one corner. The boiling water melts the surface of the wax, and allows the shell to be released, not, however, without having a thin coating of wax over the face of it, which should be washed out with a mixture of turpentine, benzole, and powdered emery.
To prepare the shell for backing, procure a small earthenware gallipot; into this place some zinc cuttings. Take it into the open air and pour on a quantity of hydrochloric acid (muriatic acid or spirits of salts). The instant the acid comes in connection with the zinc heat is generated, an offensive gas is given off, and ultimately a soldering fluid is formed, which must stand till it is cool. The back of the shell may be evenly wetted with this fluid wish a brush.
The next step is to tin and back the shell. Procure some good strip solder, fuse it, and pour from a ladle through a gauze strainer, letting it fall into water, which will cause it to become like irregular shaped spots. Some of these must be sprinkled over the back of the shell, after it is wetted with the soldering fluid.
For the next process a furnace is required, with a crane and tackle apparatus over it, to which is attached a pan, the shell being placed therein. Fix the tackle, swing the crane to its position, and lower the pan to the top of the type metal contained in the pot above the furnace. The heat must gradually extend itself to the shell and the solder, and when the solder is fused the shell will be tinned all over the back, and ready to receive the fused type-metal. The iron melting pot should be square, with a flange; it should be about three inches deep. Lower gradually, till it floats on the top of the metal.
The solder being melted, pour molten type metal (of the same temperature as the shell, if possible) over the shell, gradually and with a rotary motion, until the shell shall be covered and thick enough to enable the electrotype to undergo the process of finishing. After remaining some time, draw up the pan, and let it cool as gradually as possible. The metal for backing-in must be poor, say a hundredweight of type-metal to an equal weight of lead, and five pounds of bar tin.
The plate, when cool, must be released from the backing pan, and the face washed with turpentine, benzole, and emery powder. It must then be dried and polished by rubbing it with sawdust, and it is ready for the back being turned in the lathe. Having, by means of the plane and block, roughly squared the plate, pass a wooden straight-edge over it. Make it perfectly level, then “chunk” it into the lathe.
The back now requires to be turned, taking off at one cut not more than a Long Primer or Pica at the most. The best guage for the thickness of the plate is a Pica. The remainder of the process is the same as for Stereotypes (q.v.).
Electrotyping
A process which has come into use in place of, or auxiliary to, stereotyping, to which it is superior in two ways, especially for woodcuts or newspaper headings. The copy or plate being of copper, and therefore much harder than the type metal, long numbers can be more profitably and clearly produced; and the strokes being finer, and the sunk parts deeper, the impression from an electrotype more nearly approaches one from the type or engraving itself.
The art of plating by electricity was invented almost simultaneously by Spencer, of Liverpool, and Professor Jacobi, of St. Petersburg, in 1837; made public by the latter, October, 5, 1838, and by the former, September 12, 1839. Murray applied blacklead to non-metallic bodies as a conducting surface in January, 1840, and in the following April the first specimen of printing from an electrotype appeared in a London periodical.
For an account of the chemical processes involved, we must refer the reader to any elementary book on the subject of electro-metallurgy, as well as for a description of the utensils employed, such as the battery and the depositing trough; the metals, solutions, &c., are the same as those used in various trades which have utilized electricity in this manner.
What we propose to do is to show their special adaptation to the process of obtaining copper casts of type formes, and the system of preparing these for the press. Smee’s battery is the most preferable for this purpose.
The mechanical part of the process now familiarly known as electrotyping, consists of Moulding, Backing-in the Plates, and Finishing. Mouldings may be made from woodcuts. The most effectual moulding substance is the best yellow wax, to which two to fifteen per cent. of turpentine may be added in cold water to prevent it from cracking whilst cooking. New wax should be boiled several hours before moulding. It should be kept in a large iron fish-kettle, to be ladled out as required. Should it become burnt, it is useless.
To prepare woodcuts for moulding, lock up the woodcut in a chase with a type-high bevelled metal clump border all round it. Brush the cut over sparingly with turpentine to remove the printing ink which remains on the block from the taking off of proofs. Should the cut be an old one, and the fine lines much clogged up, which the turpentine fails to remove, it is better to brush the cuts with a hard tooth-brush, dipped in liquor potassæ. The type-high clumps prevent the wax from spreading, and the facsimile of them forming an outside border to the shell, becomes a barrier to the metal, retarding it from getting to the face of the shell during the process of backing; it also forms a wall for the dogs of the lathe to bite firmly to while the back of the plate is being turned. A wooden straight-edge should now be placed across the forme to see if the cut is of the same height as the clumps; if not, the cut must be underlaid—for it is desirable that the cut should be a trifle higher than the clumps.
Let the cut now stand until it is perfectly dry, then proceed to backlead the forme by placing it in the blackleading try, and well brush it over with the blacklead, taking care that the cut be well bronzed over, and that no particles of the lead be left in any of the fine lines of the engraving. The blacklead should be free from all adulteration.
To prepare a type forme for moulding, surround it with the bevelled type-high clumps, placing the bevelled side against the type. When locked up and planed down perfectly even, lay the forme on a board, and take it to a trough containing clean water; next mix plaster of Paris and clean water to the consistency of cream, then pour the mixture over the forme, well plastering it with the hand into the lines and spaces. Let the forme rest till the plaster begins to set, then, with a piece of reglet, scrape off the plaster level with the face of the letter, and with a water-brush wash out the plaster to the depth required, which should be to about the shoulder of the type. This process is exactly similar to the first in the plaster system of stereotyping.
Well sluice the forme at the back as well as the face, and stand it on end in the forme-rack to drain for an hour or so. After observing that the forme is tightly locked up, plane it again, so as to not crack the plaster, and see that the face of the forme is even; take it to the blacklead trough, and well bronze it all over, as described for woodcuts, taking care that the forme is dry and free from moisture. It is now ready for being moulded.
The moulding tray should be something in the shape of the forme to be moulded; it may be made of stereotyping metal. In appearance it resembles a shallow printers’ galley, but surrounded on all four sides; about a Pica or an English in depth. Two pieces of stout copper wire are soldered on to the edge in such a manner that it may be suspended in the depositing trough. Warm the moulding tray a little, lay it on a flat table, perfectly level, and with a tin ladle, pour out the wax into the tray in a continuous stream, with a slow, steady, rotary motion, within an inch or so of the sides of the moulding tray. Let the wax set all over, and then brush over the surface with plenty of blacklead, laying it on with a soft hat-brush. The sooner the blacklead is applied to the surface of the wax, without disturbing the wax or marking the surface with the hairs of the brush, the better will be the mould, as more blacklead will be held on the surface.
The forme or woodcut must be moulded while the wax is yet warm; but it must be perfectly set. The temperature of the room in which this important process is performed must be maintained at summer-heat. The wax, in cooling, ought to present a smooth and even surface. The moulding press may be either (for small jobs) a copying press or a stereotype moulding press; the higher the temperature at which the wax is moulded the less pressure required.
Now place the forme exactly under the centre of the plaster, with the moulding tray containing the slightly-warm wax upon it. The amount of pressure requisite to displace the wax must be learned by experience: too shallow an impression causes a deal of work for the building knife, and an unnecessary depth of dip may result in damage to the mould in delivery.
To deliver the mould from the forme a pair of lifters is wanted, although a thin screwdriver may be used. Insert the lifters between the furniture of the forme and the edge of the moulding tray at the top and bottom of the page, and gently, with a steady hand, apply leverage gradually until the mould is relieved from the mould or woodcut. Should the mould not be a good one, melt the wax and commence again. Never lift a mould from the sides of the form, or damage will result to the raised excrescences of the mould, which are to form the counters in the plate.
The building knife is made of copper. It is half knife and half spoon. Have close at hand a small cauldron of melted wax, and a gas jet by which to warm the building knife. Draw the knife along the projections that are to be raised still higher, and the wax will follow. The object of this is, that where paragraphs or open work occur, the parts can be lowered, to obviate the necessity of chiselling the plates, as in stereotyping. The building knife can be heated by dipping it in molten metal, and the building can be done by holding the hot knife in one hand, and a stick of hard dry wax in the other, feeding the building knife as you go along the spaces between the lines.
The mould having been finished and pronounced satisfactory, blacklead it all over, filling all its interstices and brushing the blacklead well in. Now brush all the particles of the latter, except what is bronzed on by the badger’s hair brush. If the mould be held in the light, at a certain angle, the operator may descern whether even the finest lines are highly polished. If any line or letter appears dull, the blacklead is not sufficiently blown or brushed out of such parts. To prepare the blacklead mould for immersion into the depositing trough, paint the back and sides, and also the edges of the moulding tray, leaving a spot here and there all round for the copper deposit to start from. These spots may be slightly scraped bright, to facilitate the deposit of the copper, which will shoot out from these spots towards the centre of the blackleaded surface, gradually covering it.
As soon as it is placed in the depositing trough containing the copper solution, the moulding tray containing the mould must be hung to the brass rod of the depositing trough with brass S hooks. The connections must be all clean and bright. The connection of the battery having been made, and the copper plate to be reduced placed in its proper position, the current of electricity being complete, submerge the mould in the sulphate of copper solution, hang on to the S hooks, and see that the whole of the moulding frame is under the solution, where it can remain until the deposit is sufficient to enable you to judge if all is going well. Should the copper deposit in places where it is not required, the spot must be dried, and the place stopped out with hot wax. The time usually occupied to deposit thick enough for ordinary purposes is twenty-four hours; but this must be regulated by judgment. To prevent air bubbles forming on the face of the mould, take it out of the trough and dip it in diluted methylated spirit (half spirit and half water).
The copper being deposited of the required thickness, proceed to disengage the shell from the wax by placing the mould with its back on an inclined board; then pour boiling water over the shell, gradually lifting it at one corner. The boiling water melts the surface of the wax, and allows the shell to be released, not, however, without having a thin coating of wax over the face of it, which should be washed out with a mixture of turpentine, benzole, and powdered emery.
To prepare the shell for backing, procure a small earthenware gallipot; into this place some zinc cuttings. Take it into the open air and pour on a quantity of hydrochloric acid (muriatic acid or spirits of salts). The instant the acid comes in connection with the zinc heat is generated, an offensive gas is given off, and ultimately a soldering fluid is formed, which must stand till it is cool. The back of the shell may be evenly wetted with this fluid wish a brush.
The next step is to tin and back the shell. Procure some good strip solder, fuse it, and pour from a ladle through a gauze strainer, letting it fall into water, which will cause it to become like irregular shaped spots. Some of these must be sprinkled over the back of the shell, after it is wetted with the soldering fluid.
For the next process a furnace is required, with a crane and tackle apparatus over it, to which is attached a pan, the shell being placed therein. Fix the tackle, swing the crane to its position, and lower the pan to the top of the type metal contained in the pot above the furnace. The heat must gradually extend itself to the shell and the solder, and when the solder is fused the shell will be tinned all over the back, and ready to receive the fused type-metal. The iron melting pot should be square, with a flange; it should be about three inches deep. Lower gradually, till it floats on the top of the metal.
The solder being melted, pour molten type metal (of the same temperature as the shell, if possible) over the shell, gradually and with a rotary motion, until the shell shall be covered and thick enough to enable the electrotype to undergo the process of finishing. After remaining some time, draw up the pan, and let it cool as gradually as possible. The metal for backing-in must be poor, say a hundredweight of type-metal to an equal weight of lead, and five pounds of bar tin.
The plate, when cool, must be released from the backing pan, and the face washed with turpentine, benzole, and emery powder. It must then be dried and polished by rubbing it with sawdust, and it is ready for the back being turned in the lathe. Having, by means of the plane and block, roughly squared the plate, pass a wooden straight-edge over it. Make it perfectly level, then “chunk” it into the lathe.
The back now requires to be turned, taking off at one cut not more than a Long Primer or Pica at the most. The best guage for the thickness of the plate is a Pica. The remainder of the process is the same as for Stereotyping (q.v.).