US3425900A

US3425900A - Coated papermaking wire

Info

Publication number: US3425900A
Application number: US391696A
Authority: US
Inventors: Bruce B Purdy
Original assignee: Appleton Wire Works Corp
Current assignee: Appleton Wire Works Corp
Priority date: 1964-08-24
Filing date: 1964-08-24
Publication date: 1969-02-04
Anticipated expiration: 1986-02-04
Also published as: ES316696A1; FI43673C; DE6606466U; NL6511045A; FI43673B; AT272822B; ES117098Y; FR1456692A; CH433954A; SE316072B; DE1294804B; BE668630A; ES117098U; GB1116743A

Description

Feb. 4, 1969 B, PURDY 3,425,900 Q COATED PAPERMAKING WIRE Filed Aug. 24, 1964 Sheet 0f 4 INVENTOR BRUCE B.FURDY ATTORNEY Feb. 4, 1969 B. B. PURDY 3,425,900

COATED PAPERMAKI NG WIRE INVENTOR BRUCE B. PURDY ATTORNEY -4, 969 B. B. PURDY 3,425,900 COATED PAPERMAKING WIRE Filed Aug. 24, 1964 Sheet 3 of 4 INVEN'I'OR l0 F7 2Q /5 BRUCE B. P URDY BYV'ZLZKY ZM ATTORNE] Fb. 4, 1969 PURDY 3,425,900

COATED PAPERMAKING WIRE Filed Aug. 24, 1964 INVENTOR BRUCE B. PURDY 'BYW W ATTORNEY United States Patent 3 Claims ABSTRACT OF THE DISCLOSURE A chromium coated papermaking wire is provided with uncoated selvedge portions along its lateral edges. This product is made on a continuous plating apparatus wherein the wire is negatively charged by contact with charged rollers and moved through a chromium ion electrolyte between a pair of cathodes. The edges of the wires between the anodes are enclosed by an adjustable shield and inert masks are formed over the edges of the anodes to shield the selvedge portions of the wire from electrolytic deposition and to provide for a gradually increasing thickness of deposition along the edges of the coated bottom portion of the wire.

The present invention relates to a coated papermaking wire wherein a central body portion of the wire is coated and selvedge portions on the lateral periphery of said wire are uncoated. The present invention also resides in apparatus and processes whereby a coating may be electrolytically deposited so that only a central body portion of the wire is coated and selvedge portions on the lateral periphery of said wire receive no coating.

Since the recent development of successful chromium coated papermaking wires, records have been maintained on the performance of each coated wire manufactured. Of the very small proportion of premature wire failures occurring, the most comm-on cause of failure recorded is edge cracks. Edge cracks are cracks which develop in the lateral edges of the wire and grow inward from the edges until the wire is destroyed. If the edge cracking is detected early enough, it can be checked by removing a strip of wire along the edge wide enough to include the cracks. However, in a short while, new edge cracks develop in the remaining portion of the wire. Obviously, the procedure of removing strips of defective edges of the wire, if repeated too often, will also destroy the wire, and hence it is no more than a stop gap measure intended to delay the inevitable discarding of the wire.

Wires of the present invention result from the discovery that if a narrow strip along each lateral edge of a wire, hereafter referred to as the selvedge portion of the wire, is left bare and uncoated', edge cracking as a cause of premature wire failure may be eliminated. Since the paper web is not formed on the selvedge portion, the

elimination of coating on the selvedge portion will not,

cause loss of wire life due to abrasion or corrosion.

It has been found that a wire with a coated central body portion and uncoated selvedge portions may be fabricated in several ways. The desired product may be most economically achieved by preventing deposition on the selvedge portion in the first place, instead of attempting to remove a coating from the selvedge portion after the coating process is completed. Deposition of coating on the selvedge portions may be prevented by painting the selvedge portions with a block-out lacquer or a plastic film prior to the coating of the wire, or the desired result may be accomplished by means of a novel apparatus which successfully isolates the selvedge portions from the electrolytic action of the coating bath.

The latter method utilizing the new apparatus has the ice additional advantage of permitting a progressive increase in the exposure of the body portion of the wire from the edge toward the center so as to achieve a coating which has tapered thickness along its lateral edges. Such a coating gradually reduces the flexibility of the wire from the bare selvedge portions to the full thickness of the coating toward the center of the body portion, precluding the formation of a line of stress concentration between the body portion and the selvedge portions of the wire. The apparatus utilized for that purpose also produced the additional unanticipated advantage of promoting a more uniform deposition of coating on the body portion of the wire for reasons which are more easily set forth in light of a full disclosure of the apparatus.

Although the specific embodiment disclosed and discussed here is a Fourdrinier papermaking wire of bronze or brass warp and weft strands woven together in semitwill to provide a fine mesh fabric with its ends joined to make it endless, the term papermaking wire is intended to include any type of foraminous belt, Whether it be of woven wires or perforated sheet material, whether it be endless or not, and regardless of the type of machine it is used on or the location of its use in a machine. Insofar as the problem solved is not confined to chromium coated wires, so the term coating is not limited to electrodeposited chromium but is intended to include any appropriate material, however deposited. Although the word selvedge in some contexts connotes a special weave, no such connotation is intended in this discussion where it means simply an uncoated strip along the lateral edge of a wire.

Accordingly, it is an object of the present invention to provide a coated papermaking wire that is not subject to premature failure as a result of edge cracking.

It is another object of the present invention to provide a coated papermaking wire with uncoated selvedge portions wherein there is substantially no line of stress concentration where the coated body portion of the wire meets the bare selvedge portion.

It is another object of the present invention to provide a papermaking wire having a coating electroplated on its body portion and bare selvedge portions wherein the coating on the body portion gradually increases in thickness from the selvedge portion inward.

It is another object of the present invention to provide apparatus for the electrodeposition of a coating on the body portion of a papermaking wire while preventing deposition of coating on the selvedge portions of the wire.

It is another object of the present invention to provide apparatus for the electroplating of a papermaking wire so that the selvedge portions remain bare while the body portion is coated with a minimum of additional expense.

It is another object of the present invention to provide apparatus for effecting a more uniform electrodeposition of a coating on a papermaking wire.

The foregoing and other objects will appear in the description to follow. In the description, reference is made to the accompanying drawing which forms a part hereof and in which there is shown by way of illustration a specific embodiment in which this invention may be practiced. This embodiment will be described in suflicient detail to enable those skilled in the art to practice this invention, but it is to be understood that other embodiments of the invention may be used and that structural changes may be made in the embodiment described without departing from the scope of the invention. Consequently, the following detailed description is not to be taken in a limiting sense; instead, the scope of the present invention is best defined by the appended claims.

In the drawings:

FIG. 1 illustrates in perspective a chromium coated, woven Fourdrinier wire made according to the present invention,

FIG. 2 is a plan view of a segment of the wire shown in FIG. 1 taken along one edge to illustrate in detail the coated body portion and bare selvedge portion of the wire,

FIG. 3 is a view in section of the wire segment shown in FIG. 2, taken along the line 3-3 in FIG. 2,

FIG. 4 is a side view with portions broken away of the plating part of wire plating apparatus embodying the present invention,

FIG. 5 is a rear view in section of plating apparatus embodying the present invention taken along line 55 in FIG. 4,

FIG. 6 is a front view in section of plating apparatus embodying the present invention taken along line 6-6 in FIG. 4,

FIG. 7 is a plan view showing the spacial relationship of an anode mask and a wire shield of the apparatus embodying the present invention taken along the line 77 in FIG. 4,

FIG. 8 is a view in section of a portion of a plating apparatus embodying the present invention and taken along the line 88 in FIG. 4,

FIG. 9 is a perspective view of a wire shield for a plating apparatus embodying the present invention,

FIG. 10 is a perspective view of a mask for an upper anode in a plating apparatus embodying the present invention, and

FIG. 11 is a perspective view of a mask for a lower anode in a plating apparatus embodying the present invention.

The illustration of a product embodying the present invention shown in FIG. 1 is a woven wire 1 for a Fourdrinier type papermaking machine. The size of the wire 1 will, of course, vary with the size of the machine on which it is to be used, and at this time wires are made in widths as great as 350 inches, and lengths up to 400 feet. In the drawings, the wire 1 is shown to have a central body portion 2 which is provided with a chromium coating 3 and a selvedge portion 4 which is peripheral to and bordering on the body portion 2 and which is uncoated or bare.

FIGS. 2 and 3 illustrate in detail the structure of the wire 1 shown in FIG. 1. These figures show warp strands 5 and weft strands -6 woven in semi-twill. The warp and

weft strands

5 and 6 are very fine wires, ranging in diameter from about 0.003 inch to 0.016 inch. Commonly, the

strands

5 and 6 are made of some copper alloy such as brass or bronze, and a phosphor bronze seems favored, though other metals such as stainless steel have also been used, as have polyamid monofilaments. The thickness of the chromium coating 3 may be varied from one side of the wire 1 to the other, the inside or wear side 7 of the wire 1 being given approximately 1.4 to 3 times as thick a coating as the outside, or papermaking side 8 of the wire 1. Generally, the chromium coating 3 on the wear side 7 of the wires 1 commercially produced have been about 0.0001 inch thick, and the coating on the papermaking side 8 of the wire 1 is about 0.00007 inch thick. These dimensions for the thickness of the chromium, however, are only approximate. The width of the selvedge portion 4 of the wire 1 is not precisely critical, and generally the selvedge portion is one-half inch to an inch and a half wide. It the selvedge portion is made too narrow, then the desired effect of preventing edge cracking will not be achieved, and on the other hand, since the selvedge portion 4 of the wire 1 is not used in the formation of the paper web on a machine, an excessively wide selvedge would simply result in excessive waste.

The preferred embodiment of the wires 1, as shown in FIGS. 1 to 3, are coated on the apparatus shown in FIGS. 4 through 11, and the edges of the ch mium coating 3 are tapered in thickness, as appears most clearly in FIG. 3. This taper is approximately one and one-half inches long so that a very gradual build-up of the chromium coating 3 is achieved. Since the effect of the chromium coating 3 is to make the

strands

5 and 6, and the wire 1 as a whole, more stiff, an abrupt, build-up of the chromium coating 3 at the edge of the body portion 2, instead of the tapered build-up shown in the drawings, would result in a line of stress concentration between the bare selvedge portion 4 and the coated body portion 2. Such a line of stress concentration under certain circumstances could result in a premature cracking of the wire 1 along that line due to the flexing of the edge of the Wire 1 in the course of its normal use. However, by tapering the thickness of the chromium, the increase of the stiffness of the wire 1 is gradual instead of abrupt and stress concentration is thereby minimized. Under circumstances where stress concentration presents no substantial problem, tapering of the edges loses practical importance.

Since the chromium coating 3 is deposited on a body portion of the wire 2 by an electrolytic process which will be explained later in greater detail in connection with FIGS. 4 through 11, the bare selvedge portions 4 are more economically achieved by isolating the selvedge portions 4 from the electrolytic action than by attempting to strip the selvedge portions 4 of chromium after the entire wire 1 has been coated. Several methods may be used for isolating the selvedge portions 4 from the electrolytic process. According to one procedure used the selvedge portions 4 of the wire 1 are painted with a block-out lacquer prior to plating. This block-out lacquer is easily stripped of the wire by chemical processes, after the plating process has been completed, so that uncoated selvedge portions 4 may be achieved. Another similar method producing a somewhat different final product calls for coating the.

selvedge portions of the wire with plastic prior to plating. Unplated wires have been sold in the past with plastic coatings on the edges to enhance the life of the edge portions. Accordingly, by coating the selvedge portions 4 with the same plastic prior to electroplating the body portion 2, the desired avoidance of electrodeposition of chromium on the selvedge portions 4 can be achieved and the plastic coating need not be stripped from the selvedge portion 4 before using the wire 1 on a papermaking machine.

Neither of the above mentioned methods achieve the tapered thickness of the chromium coating 3 along the edges of the body portion 2, and both of those processes increase the manufacturing costs by the lacquer or plastic coating material utilized and the labor required in its application. The idea was conceived of isolating the selvedge portions 4 by special plating apparatus which only progressively exposes the adjacent edges of the body portion 2 so that the exposure of the body portion 2 to the electrolytic process would only gradually increase from the edges of the body portion 2 towards the center. By this process, it was found that a chromium coating 3 of gradually increasing thickness, or having tapered edges, could be achieved on the body portion 2.

FIGS. 4 through 11 illustrate one embodiment of an apparatus of the present invention whereby a chromium coating 3 on the body portion 2 may be achieved having tapered thickness along its edges, while the selvedge portions 4 remain bare. This apparatus has the further advantage over the other methods in that the desired product may be achieved in the normal course of chromium plating the wire without additional manufacturing expenses.

FIG. 4 is the mostcomprehensive view of the plating apparatus embodying the present invention, and it will be noted that only the plating part of the apparatus is shown. What is omitted from FIG. 4 is the electrical circuitry, and the Wire support and drive apparatus for the wire outside of the plating part. Since the omitted portions of the plating apparatus are not critical to the present in vention, clarity of disclosure is served by leaving them out of the present description, but one type of mechanism which may be used to support and drive the wire 1 and to establish the desired electrical conditions is taught in the copending application of Martin A. Golden, and John I. Vlossak for Process and Apparatus for Making Chromium Coated Papermaking Wires, Ser. No. 339,290, now US. Patent No. 3,346,466, which may be studied if further information is desired.

Referring now specifically to FIG. 4, the wire 1 is suspended to pass through an electrolyte 9 in a plating tank 10, from the right to left in the drawing, about a pair of inert guide rolls 11 and 12 and a negatively charged contact roll 13. The first inert guide roll 11 is mounted in the plating tank so that most of it is submerged in the electrolyte 9 with only a brief portion at the top emerging, and the second inert guide roll 12 is mounted above the surface of the electrolyte 9. Hence, the wire 1 is supported in the electrolyte on an incline from the horizontal between an upper anode 14 and a lower anode 15 mounted on the same angle. The electrolyte 9 is a conventional chromic acid plating solution which is continually circulated from a large reservoir (not shown) and fed in at the bottom of the plating tank 10, and overflowing into a return trough 16 from which it is conducted back to the reservoir (not shown). The lower anode 15 stands on the bottom of the plating tank 10 and the upper anode 14 is suspended from an exhaust hood 17, both anodes being made of lead The plating tank 10 is steel with an inert plastic lining and it is electrically isolated from the rest of the apparatus.

About the ends of the upper and

lower anodes

14 and 15, respectively, are fitted an upper anode mask 18 (see FIG. 10) and a lower anode mask 19 (see FIG. 11). The upper anode mask 18 has a face portion 20 and two edge portions 21 which extend upward at an acute angle from the edges of the face portion 20. The face portions 20 of the upper anode masks 18 have wedge-shaped notches cut from their inward facing edges so that the upper anode masks 18 expose a progressively increasing area of the upper anode 14 as they extend inwardly from the ends of the upper anode 14. The edge masks 21 enclose both edges of the upper anode 14 across the entire length of the upper anode masks 18. The lower anode masks 19 are constructed in a manner similar to the upper anode masks 18, and they have face portions 22 and edge mask portions 23 extending downward from the front and back edges of the face portions 22. The lower mask face portions 22, like the upper mask face portions 20, have wedge-shaped notches cut from their inward edges so as to expose a gradually inwardly increasing area of the lower anode 15 to the wire 1, and the lower mask edge portions 23 wrap around the front and back edges of the lower anode 15 along the entire length of the lower anode masks 19. The upper and lower anode masks 18 and 19 are made from an inert, dielectric, relatively rigid material, such as plastic, and they are fitted about the upper and

lower anodes

14 and 15, respectively, so that they may be slid along the

anodes

14 and 15 so as to mask dififerent portions of them depending on the size of the wire 1 being plated and the size of the selvedge portions 4 desired.

Between the upper and

lower anodes

14 and 15 at each end, is positioned a wire shield 24 of an inert, dielectric material, such as plastic, which has an inwardly extending upper wing 25 and an inwardly extending lower wing 26 spaced apart sufiiciently to permit the lateral portions of the wire 1 to pass between them and still being as close together as possible consistent with the free movement of the wire 1. The upper and

lower wings

25 and 26 of the wire shield 24 also have wedge-shaped notches cut from their inward edges so that the wire 1 will be subjected to a gradually increasing exposure from the lateral edge of the body portion 2 towards the center. At the apex of the wedge-shaped notches in each of the upper and lower wings 25 and 26 a wire guide tongue 27 projects inwardly and is flared away from the plane of the wire 1. The wire guide tongue 27 has been found in practice to be a very efiective device for guiding the wire 1, which oscillates in its movement through the plating tank, between the

wings

25 and 26 of the wire shield so as to prevent the wire 1 from escaping from the wire shield 24 or becoming hung up on the wire shield 24.

The wire shield 24 is mounted for lateral movement to follow the edges of the wire 1 as closely as possible as the wire 1 moves through the electrolyte 9, and to adapt to wires of different width automatically. The wire shield 24 is suspended from a support arm 28 which is fastened to a truck 29, which in turn rides on a track 30 on the back of the exhaust hood 17. The truck 29, as it appears in FIG. 5, has a cross-shaped chassis 31 mounting two grooved wheels 32 on the horizontal member which ride on the top of the track 30 and one grooved wheel 33 at the bottom of the vertical member which rides along the bottom of the track 30. At the top of the vertical member of the chassis 31 is a horizontal wheel 34 bearing against the back of the exhaust hood 17 to position the inclined wire shield 24 accurately in a vertical plane between the upper and

lower anodes

14 and 15. Inwardly of the trucks 29 on the track 30 are vertical, downwardly extending spring posts 35. Expansion bias springs 36 connect the lower ends of the spring posts 35 with the support arm 28 of the wire shield 24, pulling the wire shields 24 inwardly against the edges of the wire 1.

The relative positions of the wire shields 24 and the upper and lower anode masks 18- and 19 are, in the particular embodiment shown, important to achieving the desired tapered chromium coating 3 on the wire 1. The apexes of the wedge-shaped notches on the inner edges of the anode masks 18 and 19 and the wire shields 24 should be in alignment, centered upon the upper and

lower anodes

14 and 15. The wire shield 24 has its wings so shaped that the apexes of the notches in the Wings reach to the boundary between the body portion 2 and the selvedge portions 4 of the wire 1. The apexes of the anode masks 18 and 19 on the other hand, should be positioned above and below the outer edges of the selvedge portions 4 of the wire 1. As a result of this alignment of the anode masks 18 and 19 and the wire shields 24 the selvedge portions 4 of the Wire remain completely free of any electrodeposited chromium and the body portion 2 received a chromium coating 3 having tapered thickness along the edges extending from the apexes of the notches in the wire shield 24 to the inner extremity of the anode masks 18 and 19. To achieve the proper plating result, it is important that the

wings

25 and 26 of the wire shield be as close as possible to the wire 1 as it passes between the

anodes

14 and 15.

It is disclosed above that the notches on the inner edges of the anode masks 18 and 19 and the wire shield 24 serve the purpose of gradually decreasing the area of masking and shielding so as to increase gradually the exposure of the wire 1 to the electrolytic process, and thereby to increase gradually the amount of chromium deposited. It follows from that disclosure that there are many shapes which may suitably achieve the same effect. For example, even a rectangular shape without notches may be used, if the masks 18 and 19 and shield 24 are so shaped as to be spaced gradually further from the

anodes

14 and 15 and the wire 1, respectively, as they extend inwardly from the edge of the wire 1. The preferred embodiment shown has the advantage of providing a readily controllable plating eifect as it permits the edges of the anodes -14 and 15 to be completely masked across the entire area of tapered plating thickness, which is advantageous since high current densities tend to form along relatively sharp edges. Utilizing this apparatus with its movable suspension of the wire shield produces a chromium coated woven wire which has a striking visual effect with its highly symmetrical, shiny chromium central body portion 2 bordered by bright copper-colored selvedge portions 4.

In the operation of this apparatus, the wire 1, which is supported on a suitable wire support and drive mechanism (not shown), is connected to a negative pole of an external current source (not shown) through contact wtih one or more negatively charged contact rolls, such as the contact roll 13 shown at the left hand side of the drawing. As the wire enters the electrolyte 9 from the right hand side of the plating tank It) as shown in FIG. 4, it passes behind and beneath the inert guide roll 11, which by its partially submerged position shields the wire 1 from electrolytic action during its first entry into the electrolyte 9.

After the wire passes beneath the roll 11 it enters immediately between the upper and

lower anodes

14 and 15 which are connected to a positive pole of the external current source (not shown). From the bottom of the inert guide roll 11, the wire 1 follows an upwardly inclined path through the electrolyte 9 so that it emerges from the electrolyte very shortly after passing beyond the trailing edges of the upper and

lower anodes

14 and 15 to minimize the exposure of the wire 1 after it leaves the upper and

lower anodes

14 and 15. Just above the surface of the electrolyte 9, the wire 1 passes under the upper inert guide roll 12 and around the top of negatively charged contact roll 13 and back to the wire support drive apparatus (not shown).

The corrosive and explosive gases usually emitted from such an electrolytic process are drawn up into the exhaust hood 17 and disposed of. To assure accurate temperature control of the electrolyte 9, and uniform ion control in the electrolyte 9, the electrolyte 9 is constantly circulated from a reservoir (not shown) through the plating tank 10, and into an overflow trough 16 and back to the reservoir (not shown). To achieve the desired weight of chromium deposition on the wire 1, the speed of the movement of the wire to the electrolyte 9 is governed according to the magnitude of the current flow. If high current flow is achieved, the wire may be moved more rapidly, and if low current flow is achieved, the wire must be moved more slowly, since the duration of exposure and amount of current flow vary inversely one with the other for any given weight of deposition. In order to visualize the operation of the apparatus shown in the drawings, it may help to assume that the wire is moving at the rate of about 4 inches per minute.

In order to achieve the bare selvedge portion 4 approximately one inch wide, which dimension has been chosen for commercial use, the upper and lower anode masks 18 and 19 are positioned on the ends of the upper and

lower anodes

14 and 15, respectively, so that the apexes of the notches in the inner ends of the anode masks 18 and 19 are aligned with the lateral edges of the wire 1, and the wire shield 24 is constructed so that the apexes of the wedge-shaped notches cut on the inner edges of the

wings

25 and 26 extend to within about one inch from the lateral edge of the wire 1. The wire shields 24, being mounted for lateral movement with respect to the wire 1 and spring biased inwardly, tend to bear against the edge of the wire 1 at all times so as to maintain the optimum shielding of the wire 1 as well as to stabilize the wire 1 while it is passing between the

anodes

14 and 15. Although a spring biasing mechanism is shown for the mounting of the wire shields 24, it will be understood that equivalent electrical pneumatic, hydraulic or mechanical devices could be used to provide the desired bias, here referred to as spring bias.

As a result of the delicacy of the warp and weft strands and 6 which lend great flexibility to the Wire 1, the immense width of the wire 1, up to 350 inches, and the constant circulation of the electrolyte 9, it will be evident that there is a natural tendency of the wire 1 to flutter and oscillate as it passes between the

anodes

14 and 15. Should the wire 1 contact one of the

anodes

14 or 15, a damaging short in the electrical system could occur, and, in any event, evenness of deposition in view of the very fine thicknesses of coating achieved is difficult to maintain even if the wire 1 is stabilized, and impossible to achieve if the wire 1 is permitted to flutter too much. Hence, in stabilizing the position of the wire 1 as it passes between the

anodes

14 and 15, the wire shield 24 performs a second function in the plating process, namely: promoting a uniform thickness of deposition across the entire width of the wire and preventing wire 1 from contacting the

anodes

14 or 15.

The disclosed embodiment of the present invention utilizes structure of proven and well established effectiveness, and its shape and structure is presently deemed preferable in terms of cost, ease of manufacture and ease of operating over other embodiments tried. Implicit in the structure disclosed is the generalized form from which many diverse embodiments can be made achieving the same results in the same manner and thus embodying the same invention. If it is desired to achieve a chromium coating sleeve with tapered edges so as to avoid the possibility of lines of stress concentration, anode masks, or wire shields or both should be utilized so that they gradually increase the exposure of the wire 1 to electrolytic action. But if the tapered thickness is not desired, it is only necessary to isolate the selvedge portions 4 and the additional masking and shielding may be eliminated. In the alternative, masking and shielding apparatus may be eliminated entirely in favor of the process disclosed above whereby the selvedge portions 4 are painted or coated with a suitable lacquer or plastic material prior to the electroplating procedures so as to isolate the selvedge portions 4 from electrolytic action.

Variations of the disclosed wire product and of the disclosed processes and apparatus for making the wire product may be multiplied seemingly without end and without departing from the present invention, which is therefore particularly pointed out and distinctly claimed in the following numbered claims.

I claim:

1. A papermaking wire comprising the combination of an endless foraminous belt having a central body portion and narrow peripheral selvedge portions bordering lateral edges of said body portion;

a protective coating enclosing the surfaces of said body portion, and said narrow peripheral selvedge portions being without said protective coating.

2. A papermaking wire as set forth in claim 1 wherein said protective coating has tapered thickness along said lateral edges of said body portion adjacent said selvedge portions.

3. A papermaking wire comprising the combination of an endless woven wire belt of fine mesh having a central body portion bordered along its.lateral edges by narrow selvedge portions;

and a chromium coating covering said body portion and having its thickness tapered at said lateral edges adjacent said narrow selvedge portions.

References Cited UNITED STATES PATENTS 3,177,113 4/1965 Golden et a1 162-348 DONALL H. SYLVESTER, Primary Examiner.

A. C. HODGSON, Assistant Examiner.

US Cl. X.R.