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Generally speaking: For full-bonded interfacing and interfacing that requires a permanent bond, a heat press should be used for bonding; an iron should only be used for certain types of decorative interfacing or for bonding certain types of interlining.
The temperature for iron bonding must, of course, be kept within the permissible range, just as with a fusing machine. The temperature should reach the melting point of the hot melt adhesive and be kept as low as possible.
When bonding with an iron, apply pressure for about 4 to 6 seconds per area at the appropriate temperature. The key is to ensure even bonding.
When conducting a bonding test, set the temperature, pressure, and bonding time according to the recommended bonding conditions, and verify that these three parameters are functioning properly on the machine before proceeding with the test.
Adhesive strength (peel strength) after fusing the lining to the fabric
Check for any adhesive seepage
Note any changes in the hand feel of the fabric after lamination
Changes in shrinkage (including both thermal shrinkage and wash shrinkage)
Changes in the fabric’s appearance (such as discoloration, pilling, marks, or glossiness)
The entire test must be conducted one hour after the fusing machine has been turned on
The relationship between fusing temperature, fusing time, and fusing pressure: Lowering the temperature requires extending the time or increasing the pressure, while raising the temperature allows for shortening the time or reducing the pressure.
The relationship between time and pressure: As bonding time increases, pressure can be appropriately reduced, but the minimum required pressure must still be maintained. Extending bonding time and relatively reducing the pressure exerted by the machine on the fabric—especially high-count fabrics—is an effective measure for preserving the fabric’s texture and appearance.
Bonding Temperature: This refers to the temperature at the contact surface between the fusible interlining and the fabric during the heat-pressing process, also known as the adhesive temperature. If the temperature is too low, the hot-melt adhesive will not melt; if it is too high, it may damage the fabric, cause excessive thermal shrinkage, affect the hand feel, and in severe cases, lead to adhesive seepage—where the adhesive leaks onto the fabric surface.
Bonding Pressure: If the pressure is too low, the hot melt adhesive will not adhere to the fabric; if the pressure is too high, it will alter the fabric’s properties, such as drape and breathability.
Bonding Time: Bonding time is directly proportional to the fabric’s weight (thickness); the thicker the fabric, the longer the bonding time required.
Peel strength refers to the average force required to separate a fusible interlining from the fabric it is bonded to by rotating it 180 degrees.
Wide range of thicknesses: Specifications range from less than 20 g/m² to more than 80 g/m².
Fibers can be dyed beforehand, eliminating the need for pretreatment.
The fabric generally has no specific direction of stretch, so cutting can be done without regard to orientation, making it convenient to use.
Due to the random arrangement of fibers, it is suitable for bonding with various fabrics, resists wrinkling, and is particularly suitable for lightweight fabrics.
Generally speaking, the bond strength (also known as peel strength) follows this order: 100% cotton > nylon > wool > acrylic > polyester.
Napping involves using a needle-punched napping machine to raise the fibers on the reverse side of the interlining, creating a uniform and dense layer of fiber nap.
Improves the fabric’s hand feel and enhances softness.
Prevents adhesive bleeding during pressing.
Improves iron glide.
Prevents fraying of fabric edges caused by cutting.
The base fabric of woven interlinings has a decisive impact on the quality of the interlining.
The width of the base fabric should be as consistent as possible. If the width is inconsistent, the wider sections will lack powder during dot coating, while on the narrower sections, once the hot-melt adhesive powder melts onto the embossing or heating rollers, it is difficult to remove. Inconsistent width also hinders subsequent processing, leading to poor dot transfer and affecting the bonding strength between the interlining and the fabric. Additionally, it creates difficulties during garment cutting.
While maintaining a low fabric shrinkage rate, the base fabric should possess a good hand feel. High-end apparel fabrics typically have excellent elasticity and hand feel, so the interlining used with them must also have a low shrinkage rate and a good hand feel. This prevents curling or bubbling after bonding and washing, which could otherwise compromise the fabric’s inherent aesthetic appeal.
Surface defects on the base fabric must be minimized as much as possible. The presence of surface defects adversely affects the coating process; for example, creases on the base fabric can lead to uneven powder distribution, missing powder spots, and fabric crushing. Meanwhile, the presence of sizing spots or ruffles can cause holes in the base fabric, edge bulging, and edge crushing, severely affecting the quality of the interlining.
Polyethylene (PE) adhesive interlinings are suitable for shirts and similar garments. Among these, low-pressure high-density polyethylene (HDPE) adhesive interlinings offer good wash resistance, but require a bonding temperature of approximately 170°C. They are easy to bond.
Polyamide (PA) fusible interlining offers a certain degree of resistance to dry cleaning and machine washing, with excellent elasticity and drape. It is suitable for use as interlining in various outerwear, such as suits. Some high-melting-point PA fusible interlinings can withstand dry cleaning and machine washing even at 60°C.
Polyester (PES) fusible interlining has a high melting point, good wash resistance, a pleasant hand feel, and strong bonding strength. It is particularly suitable for pure polyester or polyester-cotton blended fabrics. It is generally used for shirt collars.
Ethylene-vinyl acetate copolymer (EVA) fusible interlining has a low melting point and is not wash-resistant; it is suitable for use as fur lining.
Saponified ethylene-vinyl acetate copolymer (EVAL) fusible interlining has a moderate melting point and offers some wash resistance; it is suitable for silk, lightweight synthetic fiber garments, and linings for shoes and hats.
Good bonding performance, meaning a high peel strength can be achieved with a small amount of adhesive.
A low melting temperature (90–140°C) to allow for coating or fusing at lower temperatures without affecting the fabric’s hand feel or damaging the fibers.
Good melt flow for easy coating and fusing, without adhesive bleeding.
Good washability, withstanding multiple wet washes and dry cleaning (perchloroethylene).
Good thermal stability and resistance to aging; soft hand feel; harmless to humans; odorless.
Suitable powder properties, reasonable price, and ease of use.
Hot melt adhesive, commonly referred to as hot melt, is a type of solid adhesive based on thermoplastic polymers. When heated, it melts into a viscous adhesive fluid that penetrates fabrics or other materials; upon cooling, it solidifies and bonds them together.
