• High moisture content in the fabric or interlining; moisture in damp fabric vaporizes at high temperatures, forming steam bubbles (especially during sealed pressing). It is recommended to ensure the fabric’s moisture regain is ≤ 6% before pressing;

• The interlining is not laid flat, resulting in wrinkles or overlaps;

• Moving the fabric during pressing causes misalignment of the adhesive layer;

• Using a dirty pressing table (residual adhesive residue and dust affect adhesion);

• Performing wet-heat treatments such as washing, steaming, or setting after bonding; if the bond strength is insufficient, bubbling is likely to recur;

• Fabric is too thick or too dense (e.g., high-count, high-density poplin, coated fabrics), making it difficult for hot-melt adhesive to penetrate;

• The fabric contains elastic fibers (e.g., spandex), resulting in a significant difference in heat shrinkage rates between the fabric and the interlining; stress release upon cooling causes bubbling;

• The fabric surface has water-repellent finishes, coatings, or oil treatments, which affect the adhesive’s wetting and adhesion;

• The hot-melt adhesive granules are too fine, or the melting point is incompatible with the process;

• Special post-treatment processes are incompatible with the hot-melt adhesive granules;

Temperature Too High or Too Low

Temperature too high: The hot-melt adhesive melts excessively, decomposes, or carbonizes, producing gas that forms bubbles;

Temperature too low: The adhesive does not melt sufficiently, preventing it from penetrating the fabric fibers; the bond is weak, and the material shrinks and bubbles after cooling.

Insufficient or Uneven Pressure

Insufficient pressure → Poor contact between the adhesive and the fabric;

Uneven pressure (e.g., uneven ironing table, deformed pressure plate) → Localized areas fail to bond, creating voids.

Inappropriate Duration

Time too short → The adhesive has not fully melted and penetrated;

Time too long → The fabric is overheated, causing moisture to evaporate and form steam bubbles, or the adhesive to age and become brittle.

Insufficient cooling

Moving or folding the fabric before it has cooled sufficiently after bonding → The adhesive layer has not cured; external forces cause micro-bubbles or delamination.

Lightweight nonwoven fusible interlining: Less than 20 g/m²

Medium-weight nonwoven fusible interlining: 20–30 g/m²

Heavy-weight nonwoven interlinings: 30 g/m² and above

Nonwoven interlinings used in apparel are primarily light-weight and medium-weight. For lightweight fabrics (such as silk), light-weight and ultra-light-weight nonwoven interlinings weighing 20 g/m² or less are commonly used.

Based on performance characteristics, they can be classified into non-adhesive, partially adhesive, and fully adhesive types.

Based on shape and characteristics, they can be classified as follows:

• Straight interlining—strips cut into bands of varying widths along the warp and weft directions depending on the application.

• Bias interlining—including regular bias, narrow bias, and wide bias.

Common specifications include 60°, 45°, 30°, and 12°, with widths similar to those of straight interlining.

A strip-shaped adhesive interlining used to reinforce specific areas of garments. It is used to reinforce and strengthen areas such as the armhole, neckline, hem gusset, sleeve gusset, pocket opening, pocket bottom, and hem edge.

Using a special process, this interfacing is made entirely of hot-melt adhesive in a spider-web-like pattern, resulting in a thin, soft texture. It is sandwiched between two layers of fabric and bonds to both sides when heated, hence the name “double-sided adhesive interfacing” (commonly known as double-sided tape). It is frequently used in piping to provide reinforcement.

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.