US2203375A

US2203375A - Process for mercerizing fabric

Info

Publication number: US2203375A
Application number: US275478A
Authority: US
Inventors: Weiss Ernst
Original assignee: Heberlein Patent Corp
Current assignee: Heberlein Patent Corp
Priority date: 1937-10-15
Filing date: 1939-05-24
Publication date: 1940-06-04
Anticipated expiration: 1957-06-04
Also published as: BE430662A; FR844549A; GB519071A

Description

- June 4, 1940.

wElss 2,203,575

PROCESS FOR MIERCERIZING FABRIC Filed Ma 24} 19:59

INVENTOR fkv'vsr M75756;

I ham 43 1M ATTO R N EYS Patented Jun, 4, mo

UNITED STATES PATENT OFFICE to Heberlein Patent Corporation,

New York.

N. Y., a corporation of New York Application May '24,

In Germany 1939, Serial N0. 275,478 October 15, 1937 4 Claims. (CL 8125) This invention relates to process for mercerizing fabrics.

More particularly the invention relates to the production of improved fabrics-piece goodscontaining vegetable fibers and having the following characteristics, i. e., a good quality of sheen or lustre; the finished fabric having, at least in one direction, that is either along the warp or weft, an increased dimension as compared with the corresponding dimension of the original fabric before treatment, the character of the mercerized fabric being such that even with the increased dimension the fabric has substantially improved stability against shrinkage. Preferably such dimension is increased sufliciently and the finished fabric is of such character that even if, subsequent to the mercerizing process, the fabric is subjected to several washing tests or to mechanical shrinkproofing treatments such as the Sanforizing treatment, it will still maintain an increased dimension in the stretched direction greater than the original dimension of the fabric before treatment, while maintaining the other good qualities of mercerized fabric such for example as tensile strength.- It is a particularly valuable characteristic of the invention that notwithstanding such increased dimension, the fabrics treated according to this process are effectively stabilized in their dimensions and therefore shrink only to a comparatively slight or negligible degree upon being subsequently subjected to repeated washing. Such fabric when produced according to the preferred manner of carrying out the process, has in addition to the above set 3 forth characteristics, a strikingly high mercerizetion sheen and softness.

With preferred practices of the process, one dimension, for example, the warp, may be substantially increased, while the weft dimension may be retained at least as large as is possible with former mercerization processes; and such reduction as occurs in the weft dimension may in general be compensated for or substantially offset by the enlarged warp dimension. This is .ofsubstantial conmiercial importance in that with the usual mercerization processes as heretofore practiced, the area of the finished fabric, after the mercerization, is substantially less than thatof the original untreated material, and furthermore, when the usual mercerized fabric is washed or subjected to a shrinkproofing treatment, its area is even further substantially reduced. These facts greatly increase the real cost of the usual mercerizationtreatment. Thus, the

' ously,

costly loss in area of the material, as well as its shrinkable character after the usual mercerizetion treatment, tend to diminish to a substantial extent the advantages of mercerization. On the other hand, with fabrics made according to the preferred practice of the present invention, these disadvantages of mercerization are not only eliminated, but the permanent gain in yardage, as a practical matter, may be sufiicient in value to offset, at least to a considerable extent, the

cost of the treatment; at the same time greatly improving the product as compared with mercerized fabrics heretofore available.

Generally stated, these results are made possible by conducting the mercerlzing treatment in such manner that the fibers are first quickly,

thoroughly and effectively impregnated substantially throughout with a caustic solution of mercerization strength, before the fibers are substantially swelled by the caustic, then while subject-- ing to caustic, permitting the fiber to thoroughly swell, substantially completely and homogeneand then tensing the fabric while it is in this state of maximum swelling; the tension being applied in such manner that it is greatest in the direction of the yarn which is mainly to impart sheen, and in this direction being of such force as to stretch the fabric beyond its original dimension (before shrinkage), and according to the preferred process, to a point beyond the elastic limit of the swelled fibers and between this limit and the breaking or tearing limit of the fabric, and retaining (but not increasing) substantially the full dimensions of the fabric pro-- duced by such tensing, while the fabric is thereafter being freed of the caustic solution and preferably also during tentering and finishing,

The invention consists in the novel process or combinations of process steps hereinafter more fully described by way of examples according to the preferred manner of execution, and will be more particularly pointed out in the appended claims. o

The drawing schematically illustrates one form of apparatus by way of example, which may be used for carrying out the process of the invention.

The original material to be treated according to this invention may be a fabric comprising or containing vegetable fibers, such as fabrics made of cotton, hemp, flax, linen, jute, or ramie, as well as mixed fabricsmade of these materials,

or these materials mixed with animal fibers such I The material to be treated, preferably while in the dry state, is first subjected to a penetrating impregnation with a caustic solution of men'- cerizing strength, such penetration being forcefully effected, preferably mechanically, with sufficient rapidity and thoroughness was to enable subsequent substantially complete homogeneous swelling of the fiber. Such penetration should be effected while the fabric is not under substantial tension, more particularly at least longitudinally of the yarn which is -to mainly impart the mercerization sheen. After such impregnation, the fiber of the fabric is permitted to homogeneously swell to substantially the maximum extent possible from such impregnation and subsequent application of the caustic and is allowed to shrink during the swelling, and when the fiber has reached such. condition of maximum swelling, the fabric is overstretched by the application of tension, preferably beyond the elastic limits of the fiber and greatly in excess thereof, and preponderantly in the direction of the yarn which is to mainly impart the sheen; the overstretching usually being from 3 or 4 to 7%. Thereupon while the dimensions of the fabric resulting from such overstretching are substantially maintained, the fabric is freed from the caustic solution tentered and finished in the usual manner.

In performing the process, it is particularly important that the fiber of the fabric be thoroughly, completely and homogeneously swelled, that is, thoroughly mercerized. To this end it is important that the impregnation precede any substantial swelling. Otherwise,-if the swelling begins in the outer layers of the yarn to any substantial degree before the complete impregnation, a deeper impregnation will thereby be checked or made impossible, due to the fact that the yarns are made less permeable to the caustic. Accordingly the impregnation should be efiected extremely rapidly and uniformly, since this will subsequently permit a. completely homo geneous swelling, difiicult or impossible to otherwise achieve. The forcefully efiected impregnation may therefore preferably be aided before the commencement of the swelling by the addition to the caustic solution of suitable wetting agents or mercerization adjuvants such as a material known in the trade as mercerol (a mixture of crude cresol with fat solvents such for instance as cyclohexanol) but the wetting agents alone are not sufficient to give the necessary quick and thorough penetration, it being necessary to use for this purpose an effective forceful impregnation preferably by mechanical means such for example as by a pair of squeezing rollers between which the fabric is pressed through in the presence of the mercerizing agent. The impregnation process may also be. promoted by subjecting the goods to a vacuum followed by wetting the fabric with a mercerizing caustic solution under pressure.

With prior mercerization practices it is cus tomary to speak of the degree of mercerization, thereby recognizing that with the usual practice of mercerizing, a completely homogeneous thorough swelling is not necessary. With the process of the present invention, however, a substantially complete and homogeneous thorough swelling appears to be very important, since otherwise the necessary degree of plasticity of the fiber is not obtained for rendering it possible to properly stabilize the dimensions of the strongly overstretched fabric, in accordance with the invention.

As above stated, the material is permitted to shrink during the swelling stage of the process. While in prior known mercerization processes such a shrinking step in the procedure is left optional and is therefore not required, this mode of operation has been found to be important with the present invention in order to obtain the desired effects in the finished fabric.

The specific composition of the caustic solution may be determined according to the particular properties of the goods being treated and in accordance with the known procedure for mercerizing the same.

In practicing the present invention, it is important that the over-stretching of the fabric take place at a time when the fiber is swelled to substantially the maximum amount, as distinguished for example from prior processes in which the stretching may be done during reduction of the swelling, and as for instance during the removal of the caustic solution. While in the known mercerizing processes the stretching may take place before, during or after the mercerizing, that is, prior to the removal of the caustic solution or else during the removal thereof, the stretching during the removal of the caustic solution is frequently preferred because less power is required therefor at this stage. In short,

' for the mercerizing efiects heretofore achieved,

it made little difference whether the tensioning of the fabric took, place before'or during the removal of the caustic solution. On the other hand, with the present invention, it hasbeen found to be impossible to attain the desired and effective stabilization of the fabric against shrinkage if the tensioning is not effected during the time that the fabric is in substantially its maximum swelled condition. That is, the tensioning should be applied at a time when the complete fiber has a high degree of plasticity and not before this stage or after such plasticity has been disturbed by the reduction of the swelling. If the stretching should take place while the caustic is being washed out, then the fabric will' shrink badly in subsequent washings of the finished fabric.

Both the preliminary shrinking and the tensioning of the fabric are effected preponderantly in a direction lengthwise of the yarn which is mainly to impart the sheen. That is, the direction is determined by the nature of the fabric, or whether the yarn which is to impart the sheen is located in the warp or in the weft (for example warp satin or weft satin). In the ease of muslin, where the warp and weft yarns are almost equivalent, and linen binding is present, the direction of the shrinking and overstretching is optional.

As above indicated, in accordance with the inventionthe fabric is stretched at least in one direction, or preponderantly in one direction, beyond the corresponding original dimension of the fabric, i. e., overstretched. In older publications on mercerization, it is mentioned, to be sure, that it is possible tostretch beyond the original dimension, but there only a few percent at most could have been involved since at that time it was diflicult with the machines available or which could then be built, to stretch the fabric even to the original length. And the treatments were not such that the gain could be maintained or stabilized. A more recent disclosure describes a process for the mercerization of cotton, wherein yarn is permitted to shrink and is subsequently temporarily stretched to about 4% I the tensions applied washed, even along the direction of the predombeyond its original length. In this case, also, no stabilization of the yarn length is effected, since the caustic is washed out during the stretching, and the strteched dimensions are not maintainable for various reasons, and the completed product is specified as having its original dimensions.

According to the preferred practice of the present invention thestretching is effected by applying to the fabric, tension sufficient to exceed the fiow limits or elastic limit of the swelled fibers, but below the breaking limits thereof. The flow limits or elasticity limits may be defined as the limits reached when the tension applied causes the elastic deformation (reversible elongation) .of the fibers to pass over into permanent deformation (irreversible elongation) that is, limits at which the deformation no longer substantially disappears after discontinuance of all imposed tensions. The breaking limits may be defined as the limits at which are such as to cause tearing of the fabric or substantial damage to the fibers thereof..

As above indicated, while the material is being freed from the caustic solution, tentered and finished', its increased dimensions as fixed during its state of maximum swelling or plasticity, are to be retained as nearly as possible. It is particularly important to retain the enlarged dimensions during removal of the caustic solution. This condition may preferably be fulfilled by using for the tensioning, chain mercerizing equipment in which the fabric dimensions remain constant without further trouble. One may for example use a well-known form of chain-mercerizing machine upon replacing the customary foulard equipment with a suitable impregnating assembly and by performing the various process steps so as to carry out the invention as above described. In order to obviate tearing of the goods at the pincers during the strong overstretching, the fabric may for example be conveyed to the pincer chains in a previously tensed state, by stretching it for example by means of two pairs of squeezing rollers having respectively different speeds, i. e., the second pair having a more rapid drive.

The requirement of retaining the dimensions during the removal of the caustic solution may be also fulfilled by using machines, if for example, the spreading rollers of the apparatus for removal of the caustic solution may be individually drivenv in such way that during a given interval of time substantially identical fabric areas will run over all of the rollers. The rollers of course should be arranged in such a way that slipping of the fabric thereon is precluded. Accordingly, in case the rollers are all of the same dimensions, for example, they should be driven at equal speeds.

Fabrics which have been ennobled or finished according to the preferred execution of this invention, are distinguishable by the strikingly high sheen or light reflection given in the direction of and by thev over-stretched yarns of the fabric, and by the soft pleasant feel of the fabric, whereas certain of their other important textile properties, as for instance their tensile strength,

remain the same or as good as before the treatment; One of the most conspicuous features of the product, however, is its comparative freedom from shrinkling despite the very substantial overstretching of the fabrics treated in accordance with the invention.

will shrink but slightly on being repeatedly ness and soft hand of the fabric.

chainless mercerizing That is, the finished fabric inant overstretching. Thus in this direction at least, there persists even after washing, anincreased dimension which may be regarded as a gain in the fabric yardage available from the use of the process. apparent when the process in accordance with the invention is combined with an immediately succeeding shrinkproofing process such for example as well-known mechanical shrinkproofing processes (such as Sanforizing). Whereas, when such mechanical processes have heretofore been applied to fabrics containing vegetable fiber a substantial loss of yardage, as a result of shrinking of the goods, has had to be accepted as a foregone conclusion, yet when such a mechanical process is applied to the overstretched fabrics as a part of the present invention, not only is' such loss due to shrinkage avoided, but an actual increase or gain in the yardage of the final fabric may be accomplished.

Further treatments and completion of the fabric which has been treated in accordance with the invention may be effected in desired wellknown ways. 'In particular the bleaching and bucking of the material may be effected at any desired stage, i. e., before or'after the merceriza tion treatment according to the invention.

The drawing schematically illustrates one suitable form of apparatus by way of example only, with which the process may be .carried out with a chainless mercerizing type of machine, but invention is not to be limited by or to such machine. The fabric Ill may pass over suitable guide or idler rollers ll into a vat l2 containing the mercerizing solution including the wetting agents or mercerization adjuvants. As shown the fabric in passing over a roller l3 becomes immersed in the solution and wetted, the fabric being preferably dry when it enters the solution. Having the fabric substantially dry when it enters the bath is desirable in producing the full- Almost immediately thereafter it is fed through a pair of squeezing rollers as at l4 for promoting intensive mechanical impregnation before the swelling action has opportunity to take place and while being free of any substantial tension. After leaving the squeezing rollers M, the fabric may pass over an assembly of rollers l5 within the vat I2, and it is upon these rollers that the homogeneous swelling of the fiber takes place. 'In passing from the rollers M to the rollers Hi the fabric is allowed to shrink. In case the shrinkage is desired preponderantly in the warp direction, which is advantageous, then the rollers It will be driven with a surface speed slightly faster than those of the subsequent rollers in the vat l2, and so that the fabric is advanced without any substantial lengthwise tension.

Upon leaving the vat l2, the fabric is suitably guided to and between a pair of driven sque zing rollers H5, at which time the condition of maxi-' mum swelling has been reached. From the squeezing rollers IS, the fabric is subjected to a powerful lengthwise tension as it-passes over guide roller I1, and spreader rollers l8. On the way from the rollers I5 to the squeezing rollers l6 and thence over the guide roller H, the fabric, in this particular machine, has opportunity to shrink in the direction of the weft. -As the material passes over the spreader rollers I8, it is also subjected to transverse tensioning as well as the lengthwise tensioning. The speed' of the fabric is such in any case as to allow the caustic to This gain becomes particularly the * and form as act for a sumcient time to bring about the desired thorough swelling. As the fabric leaves the rollers I 8, it has the desired overstretched the degree of stretching may be regulated to some extent. Further regu- (i. e., the position of each While passing over the rollers I 9, the caustic solution may be removed from the fabric in any desired well-known way asfor example by sprayto effect the least 80 C. v

The spreader rollers it may be so formed as to transversely tension the fabric to the desired extent while permitting of the desired length- The rollers I9 may be of such dimensions, shape to maintain constant, the lengthwise and transverse dimensions of the fabric, substantially the same as when it leaves the rollrollers E9 are accordingly preferably all alike and driven at the same speed.

During the. lixiviation at rollers I9, the'tensions in the fabric decrease, and after the lixiviation only a small pull is necessary to retain the fabric dimensions. The same is true during any subsequent finishing operations. As stated, the tension of the fabric during the washing must be such that there is no stretching of the fabric.

caustic solution dium hydroxide of 1520 0., to which is a mercerization adjuvant amounting, for example, to 2% of the solution, if mercerol is used. The solution is allowed to act for from 15 to 25 seconds between rollers I3 anddfi, which is the time required in this example for complete swellcomprising s0- B. at a temperature of somewhat longer if time for the travel desired. Suitable periods of of the fabric between other 7 with tension sufiicient to parts of the apparatus shown will then occur 11 the distances between the various rollers are proportioned substantially according. to the drawing. 'Ihe'material is so conducted through the apparatus that the fabric may first shrink quite freely (i. e., up to rollers 56), preponderantly in the warp direction forexample. This is followed by a powerful stretching at a time when the fabric has reached the condition of maximum swelling (for example between rollers l6 and I9) and increase the length of the fabric by about 7% or more, up to nearly 7%. For attaining the highest sheen with stabilized overstretching the tension should be sufficient to increase the length by about 7% or over; for the attainment of stabilized overstretching with somewhat less sheen the fabric may be overstretched to a less extent.

the powerful stretching.

brics which have been treated in accordance Fa with this example have an than obtainable with the normal mercerization.

Also the resultapoasvs invention. The tests also reveal that with the product of the invention, the degree of lustre varies much more sharply, depending upon the angle of incidence of the light, which fact is also clearly noticeable to the eye in comparing the finished fabrics and serves to give the fabrics treated according to the invention, striking variations in brightness upon changes in the position thereof in respect to the incident light.

Microscopic examination of the cross section of the fibers of fabric treated in accordance with the preferred execution of the above described process, reveals that the cross sections of a large portion of the individual fibers have somewhat polyhedral outlines as compared with more smoothly curved outlines of fibers as ordinarily mercerized. Furthermore, with the improved process, the degree of swelling of the various fibers as well as within each fiber is appreciably more uniform. The cross sections although polyhedral are more swelled out toward a circular form as contrasted with the case of ordinary mercerization where the shapes of the cross sections are preponderantly elliptical or kidney shaped, less uniform,

and smaller. With the usual mercerization procedure, many of the fibers have a somewhat ribbon-like appearance, but with the improved process there are very few fibers with such ribbonlike structure.

Although with the usual merecerization processes, the degree of mercerization is sometimes estimated by determining the ratio of the amount of dyestufi, such as benzopurpurine 4B, which will be taken up by the untreated fabric as compared with the same fabric mercerized (more dyestuif being absorbed the greater the degree of mercerization), it has been found that fabrics treated" in accordance with the preferred execution of the present invention absorb less of such dyestuff than normally mercerized fabrics, notwithstanding the greatly improved mercerization sheen.

In spite of the fact that thefabric has been strongly overstretched, standard washing tests reveal that it does not shrink in length more than about 2 to 3% as compared to its length prior to the washing. If the fabric as mercerized is subjected to a mechanical shrinking process, for instance such as Sanforizing, the Sanforized fabric may still show an increase in length of about 5 to 7% as compared with the original untreated goods. After washing the Sanforized product six times, the shrinkage tolerance of 1% is not exceeded. The Sanforizing process referred to is a well-known one and may be such as disclosed in the following patents, reference to which is hereby made: United States Patents Nos. 1,861,423, 1,861,424, 2,037,676 and 2,082,981.

With the mercerization processes heretofore used, the length of the fabric is not increased beyond 3% and generally only 1%, and when such a fabric has been subjected to washing tests or Sanforizing, it will usually show a loss of from 3 to 6%; which means that the fabric will show a loss, from its original length in the gray, of from 2 to 3%, or often even as much as 5%.

Example 2.A muslin fabric may be treated, for example, by using apparatus such as shown in the drawing, and generally in accordance with the process of Example 1, except that the longitudinal stretching may be such as to effect an elongation of 4 to 6% and with a transverse spreading of the fabric somewhat greater than Example 1. These differences from Example 1 are advisable because in the case of muslin. the

yarn which imparts the sheen is ordinarily distributed about equally in the warp and the weft. The fabric shows ,an increased silk-like lustre and the yarns seem to be thinner and the fabric somewhat finer in comparison with ordinary mer- 5 cerization.

Example 3.--A limberic" fabric may be treated in accordance with the same principles stated above in connection with the muslin fabric of Example 1. Here the yarns which predominantly impart the sheen are run in the direction at the filling and accordingly in' the mercerization bath, the fabric should be allowed to shrink predominantly along the direction of -the weft, and the over-stretching should be also predominantly along the direction of the weft. The fabric shows an increased silk-like lustre and the feel is characterized by an increased softnessand pliability in comparison with ordinary mercerization. The above mentioned stabilized character of the fabric to resist substantial shrinkage is also present in the fabric made according to this example, so that even after washings or Sanforizing a gain in the stretched dimension is maintained over that in the original fabric prior to mercerizationa This invention does not reside merely in stretching the fabric during mercerization beyond the original dimension, but it resides, as to the product, in the peculiar, new and valuable character of the finished mercerized fabric which gives it a good sheen (and in the preferred form of the invention a very high sheen and softness) and enables it to resist shrinkage to such an extent that after repeated washing tests or, after Sanforizing, it loses only about 2 to 3% of its length, and this is true even in cases where in the mercerization treatment the fabric had been stretched to a finished length of several percent. beyond its original or gray length.

While the invention has been described in detail with respect to particular preferred examples, it will be understood by those skilled in the art after understanding the invention that various changes and further modifications may be made without departing from the spirit and scope of the invention, and it-is intended therefore in the appended claims to cover all such changes and modifications.

This application is a continuation in part of my copending application Serial No. 217,646, filed July 6, 1938.

What is claimed as new and desired to be secured by Letters Patent is:

1. Process of finishing a fabric containing vegetable fiber to obtain a good mercerization sheen II and improved stability against shrinkage by subsequent washings, which comprises quickly effecting a thoroughly penetrating impregnation of the fiber with a caustic mercerization solution, such thorough penetration being effected before 00 substantial swelling of the fiber takes place so as to enable subsequent thorough and homogeneous swelling, then continuing the action of the caustic under conditions permitting "the fiber to substantially homogeneously and thoroughly swell to substantially the maximum extent the fibers during the swelling being allowed to shrink mainly in a direction of the yarn which is to principally impart the sheen, then "overstretching" the fabric while in such substantially maximum swelled condition to a point beyond the corresponding original dimension of the fabric but not exceeding 8%;beyond said original dimension, by tensioning the fabric preponderantly in said direction, and thereafter removing the caustic :6

solution from the fabric while maintaining substantially its dimensions resulting from said overstretching.

2. Process of finishing a fabric containing vegetable fiber to obtain a good merceriz ation sheen and improved stability against shrinkage by subsequent washings, which comprises quickly effecting a thoroughly penetrating impregnation of the fiber with a caustic mercerization solution, such thorough penetration being effected before substantial swelling of the fiber takes place so as to enable subsequent thorough and homogeneous swelling, then continuing the action of the caustic under conditions permitting the fiber to substantially homogeneously and thoroughly swellto substantially the maximum extent, the fibers during the swelling being allowed to shrink mainly in a direction of the yarn which is to principally impart the sheen, then overstretching the fabric while in such substantially maximum swelled condition and to a gain of about 3 to 8% in such direction, by tensioning the fabric preponderantly in said direction, and thereafter removing the caustic solution from the fabric while maintaining substantially its dimensions resulting from said over-stretching.

3. Process of finishing a fabric containing vegetable fiber to obtain a good mercerization sheen and improved stability against shrinkage by subsequent washings, which comprises quickly efiecting a thoroughly penetrating impregnation of the fiber with a caustic mercerization solution, such thorough penetration being efiected before substantial swelling of the fiber takes place so as to enable subsequent thorough and homogeneous swelling, then continuing the action of the caustic under conditions permitting the fiber to substantially homogeneously and thoroughly swell to substantially the maximum extent, the fibers during the swelling being allowed to shrink mainly in a direction of the yarn which is to principally impart the sheen, then overstretching the fabric while in such substantially maximum swelled condition and to a gain of about 3 to 8% in such direction, by tensioning the fabric preponderantly in said direction, and thereafter removing the caustic solution from the fabric by hot lixiviation while maintaining substantially its dimensions, resulting from said overstretching.

4. Process of finishing a fabric containing vegetable fiber to obtain a good mercerization sheen and improved stability against shrinkage by subsequent washings, which comprises quickly effecting a thoroughly penetrating impregnation of the fiber with a caustic mercerization solution, such thorough penetration being effected before substantial swelling of the fiber takes place so as to enable subsequent thorough and homogeneous swelling, then continuing the action of the caustic under conditions permitting the fiber to substantialy homogeneously and thoroughly swell to substantially the maximum extent, the fibers during the swelling being allowed'to shrink mainly in a direction of the yarn which is to principally impart the sheen, then overstretching" the fabric while in such substantially maximum swelled condition and ma gain of about 5 to 8% by tensioning the fabric preponderantly in said direction, and by applying suificient tension transversely of said direction to prevent transverse shrinkage in excess of about 5%, and thereafter removing the caustic solution from the fabric while maintaing substantially its dimensions'resulting from said overstretching.

ERNST WEISS.

CERTIFICA'JE 0F CORRECTION. Patent No. 2,203,375. June 1;, 19!;0.

ERNST WEISS It is hereby certified that error appears in the printed specificatioxi of the above numbered patent requiring correction as follows: Page 3, first column; line 1;, for "strteched" read stretched,--; line 72, for "shrink ling" read shrinking-; page 11., first oolmnn, line 15, for "numbers" read -mnnber--; mini second column, Line 59, for "tendered" read -tentered-; page 5, seoond column, line 66, claim 1, after "extent" insert a comma; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case inthe Patent Office.

Signed and sealed this 6th day of August, A. D.- 191m.

Henry Jan Arsdale,

(Seal) Acting Commissioner of Patents.