Clothing World presents the results of thefirst major study into the effects of fabric conditioner on the performance of garmentseams. The research outlines a number of measures that can be taken at the manufacturingstage to help reduce seam slippage — one of the principal causes of customer returns.

The seam is often the weakest point in agarment. Slippage, grin, bruising and tear can all occur at, or near, the seam, therebyreducing the garment's serviceability and drastically diminishing its aesthetic appeal.

It is hardly surprising, then, that fabricslippage is one of the principal causes of customer returns and a frequent topic ofconversation in Rob Croskell's Textile Complaints Investigation Department (CID) at theSGS Testing Laboratory in Wembley.

"Properties such as weave structure,yarn construction, garment style, seam type, stitch density and seam allowance are allwell known to manufacturers as factors which govern slippage in woven fabrics", saysRob. "However, until now, very little has been published about the deterioration ofseams in relation to fabric conditioners".

Seam strength is defined as the loadrequired to break a seam when it is stressed transversely, or pulled apart. Althoughgarments are often subjected to much lower loads than necessary for actual rupture, a seamwill be said to have failed commercially if the threads lying parallel to the seam aredisplaced. Slippage occurs when the fabric at either side of the stitching distorts andthe yarns slide away from the seam, producing a permanent gap within the fabric, oftenknown as 'grinning'.

"Seam slippage is probably of greaterimportance commercially than seam strength", says Rob. "It will almost certainlyprecede rupture and is therefore more likely to precipitate a complaint assuming thatcustomers do not wait for the seam to actually break before voicing their concerns!".

The problem came to light when complaintsof slippage and bruising were reported by corporatewear manufacturers even after testreports, produced by competent textile laboratories, stated that slippage was commerciallyacceptable. The problem was solved by SGS' CID team when residual conditioner was found onthe complaint garments and, when this was washed off, the slippage was found to return totolerable levels.

"The effects were so pronounced",says Rob, "we decided a laboratory study would be of considerable interest, not justto test houses, but to manufacturers and designers, enforcement authorities and consumersalike".

THE FABRICS
The survey consisted of testing the seam strength and slippage of sets of 50fabrics of different weaves in warp and weft directions under three conditions: as new,after washing without conditioner, and after washing with conditioner in the final rinse.

Fabrics were selected from samplessubmitted for routine performance testing and therefore reflected market trends in ladies'wear blouses and dresses with viscose, polyester and nylon dominating the sample set.Samples were also chosen to reflect their likelihood of exposure to fabric conditioner sothe team focused upon fabrics designed to be worn close to the skin, commonly made fromcontinuous filament yarns. For the purposes of consistency, plain, twill, satin andjacquard weave fabrics were selected in roughly equal number.

TEST METHOD
The test specimens were cut into 20cm x 10cm strips in warpway and weftwaydirections and a seam sewn in at a stitch rate of 5 per centimetre. Washing was carriedout according to care label instructions recommended by the manufacturer. Where fabriccomposition and washcare instructions were absent, fibre identification was performed bychemical analysis, and washing and drying instructions based on recognised test methods.

Samples were washed using a standarddetergent for one wash cycle. Those to be treated in fabric conditioner were also washedfor one cycle with a leading brand of liquid softener added in the last rinse. Recentanalysis of fabric conditioners suggested the major active ingredients (for fabricsoftening) of the leading brands were so similar that any would have been suitable.

The measurement of seam strength andslippage was carried out using a tensile test instrument with 25mm grab jaws. Doubts(expressed in BS PD 6537:Part 2:1994) regarding the credibility of the current BritishStandard Test Method for measuring Seam Slippage (BS 3320:1998) prompted the team to use amodified version — the Visual Graticule Method, which involved measuring the seamopening directly from the specimen. The load required to open the seam to 6mm (slippage)and to rupture (strength) was recorded. For each group of specimens the mean load wascalculated and the percentage loss in slippage resistance and loss in seam strength werecalculated.

A glance at the general trend reveals asignificant decrease in seam slippage resistance and seam strength in fabrics treated withconditioner. For plain and satin weave fabrics there is nearly a 50 per cent decrease inslippage resistance and jacquard fabrics are not far behind. Surprisingly, the results forthe slightly heavier, twill fabrics show significantly less reduction (approximately 30per cent) suggesting that fabric weight per unit area has a part to play in the ability toresist slippage.

As expected, the effects of fabricconditioner on seam strength were not as pronounced but were nevertheless significant. Inthe case of satin fabrics, over 40 per cent reduction in seam strength is disturbing.

CONCLUSION
So how can fabric conditioners affect seam properties to this extent?

"We believe the softener, a cationicsurfactant, is acting as a lubricant on the yarns in the weave", explains Rob,"On continuous filament yarns which have a smooth surface character, the softener isreducing the friction between warp and weft so, when a force is applied, the yarns areable to slip over one another.

"The cause of the seam rupture wasseen to be as important as the level at which it occurred. When a fabric was prone toslippage, the cause of the rupture was invariably due to the seam allowance fraying awayunder the load. Where the softener had little or no effect or no softener had been used,the seams ruptured for other reasons such as sewing thread break or fabric tear".

RECOMMENDATIONS
An obvious reaction to this evidence would be to recommend that consumers stopusing fabric conditioners. However, for several reasons, this seems to be an unrealisticexpectation. In short, the benefits perceived by the consumer outweigh the disadvantages.

Since the advent of the fabric softener,consumers have come to expect that their garments retain their original softness andsuppleness after laundering. During machine washing, textiles are subject to considerablemechanical stress and the effects of water hardness. Fibres tend to entangle and remain inthat state during drying. Thus, laundered fabrics acquire a harsh feel which can besoftened by using conditioners which lower the friction between the fibres and promotegreater fibre mobility and, furthermore, the reduction of friction on the skin produces anoverall pleasant feel.

Fabric conditioners can also bestow fresh,clean odours on garments which come out of the machine and these are less wrinkled andhence are easier and quicker to iron. Conditioners also reduce static charges onsynthetics.

With these positive benefits, it istherefore unreasonable to expect consumers to stop using fabric conditioners on theirclothes. Instead, the responsibility, it would appear, shifts onto the garmentmanufacturer. A number of well established measures can be taken at the manufacturingstage to help reduce seam slippage. These include introducing more interlacing in theweave structure and increasing the number of threads per inch; using a fibre with arelatively high coefficient of friction; choosing suitable seams, with suitable stitchrate; increasing the seam allowance; and, where practical, sewing on the bias.Unfortunately, all of these will change the character of the fabric and the garment madefrom it.

Correct fabric selection is a morepractical alternative. Indeed, this is the crucial factor which can reduce the number ofcomplaints and returns due to seam slippage. Often fabrics suited only for loose-fittingstyle garments are used for tight fitting styles. Women's blouses are particularlyvulnerable as their structural design creates acute stresses in certain areas, and theadded tensions exerted in the tight fit makes slippage inevitable, and only accentuated bythe use of conditioners. Performance testing of fabrics incorporating the use ofconditioners in the final rinse, at the pre-production stage of garment making, wouldbetter indicate the likelihood of seam slippage in use.

"Taking account of the results andwide use of fabric conditioners it may be wise for all retail performance specifications,for garments, to include testing with conditioner", says Rob. "We will berecommending the option of testing conditioned fabrics for certain "high risk"apparel and advise suppliers of blouses, especially those designed as corporatewear, toinclude conditioners when testing in future".

If a fabric performs poorly in such a testthe manufacturer has two options: to select a more robust material or take this potentialproblem into consideration when designing the garment and affixing the care label.

The study was carried out at SGS by EvelyneChui Hom Lap, an undergraduate at UMIST, and much of the material was extracted from herthird year placement report.

Table of results

Plain Twill Satin Jacquard
Slippage (%) 48.9 32.6 52.3 36.5
Strength (%) 24.7 2.8 40.8 24.7