Interlinings are fabrics used to support, reinforce or stabilize areas of garments such as collars, cuffs, waistbands, hems, facings and fronts of jackets or coats. Interlinings may be inserted between layers of fabric or sewn into the garment or maybe fused to one of the fabric layers.
Interlinings come in 2 types FUSIBLE AND NON-FUSIBLE. Fusible interlinings are coated with a resin on the base. The resin melts when heat is applied and bonds with another surface. Non-fusible interlinings are not coated with any fusible resin. Both type of interlinings are available in 3 qualities of base cloth/fabric; Woven, Non-Woven, Knitted or stretchable. All the 3 qualities of interlining are available in different weights and constructions.
Fusible interlinings are woven or formed fabrics with fusible material applied on one of its surfaces. The most common woven base of interlining is cotton in plain weave. Lighter weight fabrics give a soft handle, usually these are formed fabrics. The base of heavier interlinings is woven canvas fabric. Fusible interlinings interlinings are used in areas where stability of shapes is required. Eg.. collars, shirt cuffs, waistbands of formal trousers.
These are interlining fabrics made of synthetic bases or woven fabrics with no fusible material applied to on any of its surfaces. The base is made by forming fabric like sheets of synthetic textiles fibers, these fabrics are called formed fabrics. The process used to make formed fabrics may be mechanical, thermal or use of solvents. Many times a combination of these processes is used to produce formed fabrics. These interlinings are used when light weight and suppleness is required at area of reinforcement. Non-fusible interlinings are used to stabilize or reinforce shapes or areas of a garment in a inexpensive way. Eg.. Plackets, waistbands, colars, cuffs… of casual clothing.
KNITTED OR STRETCHABLE INTERLININGS
Knitted fabric base is used to make fusible interlinings. Stretchable fusible interlinings are used in stretch fabric garments to retain the USP (characteristic) of stretch fabrics.
Fine resin powders are blended with water and other agents to form smooth paste and printed on base fabric. The resin is applied as a dots in any shape as required. The type of resin and method of coating is chosen based on factors like cost, fusing resin characteristics, availability or suitability of fusing equipment, type of base fabric(woven, knitted or non-woven). To cover different laminating requirements, a range of resins are available. Choice of resin is restricted by limit imposed by the fabric tobe fused, the fusing equipment used, end-use requirement and precise behavior of resins in response to heat. The objective of fusible interlining’s use is dependent on performance of fusible resins applied to base fabric of fusible interlining.
The performance required of resins applied to a fusible interlining are:
- The fusing temperature required must not be so high that it will damage the outer fabric’s colour or structure. The general standards temp is 150 degrees with a maximum temp of 175 degrees C.
- The fusing temperature should not be so low that the bonding is inadequate to stay good during garment making. The general lower limit is 110 degrees C. Some materials like leather may require even lower temperature.
- The resin’s bonding must be adequately resistant to rigours of garment production process, domestic washing and while in use by wearer.
- The thermoplasticity of the resin must be such that adjustment of temperature is sufficient to permit it to penetrate the outer fabric and bond, without flowing excessively to give strike-through or strike-back.
- The resin must contribute to the achievement or the desired handle of the interlining.
- The resin must also have low dye retention properties, be biologically harmless in processing and in end uses.
METHODS OF RESIN APPLICATION TO BASE CLOTH
The properties of an interlining and its effects on the outer fabric of a garment are varied by the method of application of the resin to the base cloth. The most popular methods used are:
- Scatter Coating
- Dry dot printing
- Paste coating
All the methods involve use of carefully selected particle sizes for resins. Resin particle size is measured in microns. 1000microns = 1mm. Scatter coating uses largest resin particle size (150microns to 400microns), Dry dot printing uses medium resin particle size (80microns to 200microns) and Paste Coating uses the smallest resin particle size (01 micron to 80microns).
SCATTER FUSIBLE COATING Specifically designed scattering heads are used to provide an even scatter under automatic control. The resin is then softened in an oven, presses onto the base cloth and cooled. This is the cheapest method of making a fusible interlining. Interlinings with this method of fusible resin application are not flexible and do not bond uniformly to main fabric.
DRY DOT PRINTED FUSIBLE COATING Powdered resin fills engraved holes of a roller, the base cloth passes over the heated roller and then on the engraved roller with resin. Powdered resin adheres to the base cloth in the form of dots. Oven heating follows the printing operation to ensure permanent adhesion. The temperature and pressure on the 2 rollers is varied for different resin types. Patterns of dots can vary form 3-12 dots per centimeter as required by garment manufacturer.
PASTE COATING Fine resin powder is blended with water and/or other agents to form a smooth paste. This paste is then printed as a coating on base cloth. Heat removes water and the dots coagulate into solid resin. This type of coating gives precisely shaped dots and is used to produce the finer dots in fusible interlinings used for shirt collars.
FACTORS AFFECTING BONDING OF FUSIBLE INTERLININGS - TEMPERATURE, TIME AND PRESSURE
Correct temperature, time and pressure are required to induce melting of resin and penetration of resin to the fabric to give satisfactory bonding.
TEMPERATURE is the degree of heat being applied to interlining of to resin. Temperature should be high enough to melt resin to molten state and stick to the material. Too high temperature gives too much flow resulting in stick back or stick through. Too low temperature, interlining may not fuse or bad fusing of interlining and fabric does occur.
TIME is the number of seconds the heat and pressure is tobe applied to interlining or time for which interlining has to stay within the fusing machine.
PRESSURE is the amount of weight applied to interlining through the plates of fusing equipment.
FUSING EQUIPMENT - Types of Fusing Machines
FLAT BED FUSING SYSTEM
In this machine, the top plate is not padded but the bottom plate has resilient cover with silicon rubber. Both plates have a cover of PTFE, can be cleaned easily to prevent staining. Heating arrangement is provided at the top but sometime at the bottom also. The pressure system must be robust providing accurate closing. The operator places the garment part face down on the lower place, the fusible resin type down on top. This machine is suitable for small garment parts but it is very much suitable for stretchable material such as knitwear industries and incase of velvet fabric because the material will be pressed from both the sides. In case of printing of knitwear garments sometimes the machine is used for curing. So this machine is known as curing machine.
CONTINUOUS FUSING MACHINE
This system is used to press parts with the interlining placed on it. A heat source and pressure is applied to it simultaneously. Electronic controller controls the temperature, pressure and speed of conveyor belt. Companies engaged in high volumes of production go for this machine.
Only those interlinings which can be fused at low temperatures, hand iron is used. It is used for fusing small parts.
Fusible interlinings are precision products. It is essential that they be fused on the correct equipment and under strict control.
- A fusible compatibility test should be done to check the suitability of a fusible interlining and also to set the process for fusing.
- As a general rule, Fusible interlinings should fuse to the outer layer of garment part.
- Bubbling is not acceptable.
- Strike-through or Strike-back of resin in fusing is not acceptable.
- Fusible interlinings are used with the purpose of reinforcing and stabilizing garments areas/parts. As long as the garment is in use, the Fusible interlining has to fulfill its intended purpose in a garment.
TYPES OF RESINS
- Polyvinyl Chloride (PVC)
- Plasticised Polyvinyl Acetate (PVA)
Polyethelene coatings are available indifferent densities and with different values of a property known as the melt flow index. The value of this index determines the extent to which the resin flows during the fusing operation. Higher the value, more easily the resin flows, better the bonding. All the polyethelene used in fusible coatings are washable. In higher densities, polyethelene resins are washable and dry-cleanable. Polyethelene coatings require high pressure. Interlinings with polyethelene resins are suitable for shirt collars n cuffs.
Polyamides can have a wide range of fusing properties according to the proportions of the basic ingredients of different nylons employed as well as the amount of plasticizer added. The objectives are to vary the melting range and lower the softening temperature. Polyamides are very widely used in dry-cleanable garments. Polyamides in the higher temperature melting range are generally washable upto 60 degrees C. Polyamides in the lower temperature melting ranges are dryclean only.
Polypropylene is similar in properties to high density polyethylene but reaches its softening points at a higher temperature. This makes it especially suitable for fusing applications where rapid, high temperature drying is part of the garment laundering process. The resin will withstand temperatures upto 150 degree C before delaminating.
Polyesters have a wide range of fusing properties as a result of varying constituents. These resins are used in garments that are dry-cleanable and washable as polyesters are less water absorbent than polyamides. Therefore resists washing better.
Polyvinyl Chloride (PVC) is generally printed onto base fabric as a plasticized paste and the fusing temperature is determined by the amount and type of plasticizer used in its formation. It is dry-cleanable and washable. Commonly used in large area application on coat fronts.
Plasticised Polyvinyl Acetate (PVA) is generally in the form of a continuous coating for fusing to leather and fur at low pressures and temperatures. It is not dry-cleanable and has limited washability.
Packaging is in roll form. Fusible resins cracks if interlining is folded and in non fusible interlinings folds leave a crease mark. Each type of interlining is made in different width by different manufacturers. Unit of measurement is yards or meters. Check with supplier/manufacturer for widths available and units of measure they use as yards is lesser in quantity than meters.