The art of textile printing offers a vast spectrum of creative possibilities, enabling designers and manufacturers to produce unique patterns and textures. Among these techniques, burnt-out printing stands out for its ability to create striking transparent or semi-transparent designs on blended fabrics. This process selectively removes cellulose fibers, typically cotton, from blends containing synthetic fibers like polyester or rayon, resulting in intricate patterns with varying degrees of transparency. A fundamental component in achieving successful burnt-out effects is the specialized burnt-out printing paste, a carefully formulated chemical system designed to facilitate this selective fiber degradation.

Effective burnt-out printing relies on a combination of precisely engineered chemicals that interact under specific conditions. The core of the system often involves a strong acid-releasing agent and auxiliaries to control the reaction and improve processing. For optimal results on fabrics such as cotton, TC (Terylene/Cotton), and TR (Terylene/Rayon) blends, a multi-component approach is frequently employed. This typically includes a strong acid resistant paste component (like MF-65 described in some systems), a burnt-out powder (like MF-20), and an anti-scorch or washing auxiliary (like MF-15).

The strong acid resistant paste component (MF-65 type) serves as the carrier and application medium. It is designed to have good penetration properties and low foaming characteristics, making it easy to apply uniformly onto the fabric surface. Due to its nature, this paste may have a limited shelf life, prompting some suppliers to offer it in powder form, allowing manufacturers to prepare the paste fresh by dispersing the powder (approximately 0.65% by weight) in water (around 93.5% by weight) and stirring until completely dispersed. This on-site preparation ensures the paste is at its optimal consistency and activity for printing.

The burnt-out powder component (MF-20 type) is the active ingredient responsible for the selective degradation of cellulose fibers. When subjected to heat during the baking stage of the process, this powder releases acid, which then carbonizes the cotton fibers within the printed areas. This carbonized material becomes brittle and can be easily removed during the subsequent washing process, leaving behind the pattern created by the remaining synthetic fibers. This component is particularly effective for cotton, TC, and TR blended fabrics, delivering a clear transparency effect after washing.

An important addition to the burnt-out system is the burnt-out auxiliary (MF-15 type). This auxiliary plays a crucial role in enhancing the efficiency of the washing stage, making it easier to remove the carbonized cotton fibers and ensuring a clean, clear burnt-out effect. Furthermore, auxiliaries like MF-15 can act as anti-scorch agents, helping to prevent the fabric from blackening during the high-temperature baking process, especially when precise temperature control is challenging. The correct dosage of this auxiliary is vital; too little can lead to blackening and difficulty washing, while too much can inhibit the burnt-out effect itself, requiring higher temperatures or longer times for the reaction to occur.

The burnt-out printing process typically involves several key steps: application of the burnt-out paste onto the fabric via screen printing (ensuring adequate penetration), surface drying, and then heat treatment through baking or steaming. Baking is usually performed at temperatures between 120-140ºC for 1-2 minutes, or steaming at 95-97ºC for 3 minutes. The temperature and duration of this heat treatment are critical factors influencing the outcome. Insufficient heat leads to incomplete carbonization and unclear patterns, while excessive heat causes the fabric to blacken and can damage the synthetic fibers. After heat treatment, the fabric undergoes a washing process, often incorporating soda ash (sodium carbonate) at approximately 1-2g/L in 40ºC water to neutralize any residual acid and facilitate the removal of the carbonized material.

Achieving optimal burnt-out results depends on several factors. The fabric composition is primary; higher cotton content and thinner fabrics generally yield better effects. The dosage of the burnt-out powder directly correlates with the intensity of the effect, but excessive amounts increase the risk of blackening. Baking temperature and time must be carefully controlled; lower temperatures for longer durations are often preferred for better control and reduced risk of scorching. Adequate penetration of the paste into the fabric is paramount; incomplete penetration can result in patchy or unclear patterns on the reverse side of the fabric. Proper preparation of the paste, ensuring no air bubbles are incorporated, is also necessary to prevent spots or imperfections in the final print.

Troubleshooting common issues requires understanding the process dynamics. If patterns are clearer on the face than the back, penetration is likely insufficient, requiring paste dilution, increased squeegee pressure, or optimizing pre-treatment (ensuring fabric is hydrophilic). Blackening after baking usually indicates over-heat treatment, which can be remedied by lowering temperature, increasing speed, or increasing the anti-scorch auxiliary dosage. Absence of a pattern suggests insufficient heat treatment (acid not activated) or excessive auxiliary dosage inhibiting the reaction, requiring higher temperatures, longer times, or reduced auxiliary dosage. Spots can be caused by air bubbles in the paste or fabric imperfections.

Safety and risk mitigation are crucial when working with burnt-out chemicals, particularly the acidic components. Components like MF-20 powder are strong acids and can be corrosive to metal equipment, cement, and wood. Precautions must be taken to prevent packaging leakage and avoid contact with skin or eyes. In case of contact, immediate washing and medical attention are necessary. Operators should always carefully read product precautions and refer to the Material Safety Data Sheet (MSDS) before use.

To achieve the best results, it is generally recommended to proceed with the burnt-out process (baking/steaming) immediately after printing and washing immediately after heat treatment to prevent acid diffusion, which can blur the pattern edges. If placement time before baking is necessary, testing is required to confirm feasibility based on the specific fabric. Additionally, selecting acid-resistant disperse dyes is essential if color burnt-out effects are desired, involving adding dyes to the burnt-out paste composition.

For textile manufacturers seeking reliable and effective solutions for burnt-out printing, sourcing high-quality raw materials is key. Leading chemical suppliers offer the essential components, including the burnt-out powder, paste precursors, and auxiliaries, required to formulate or utilize burnt-out printing systems. Interested parties looking to purchase burnt-out paste components, inquire about price, or find a trusted manufacturer and supplier can explore various sourcing channels. Understanding the technical specifications and recommended usage guidelines is vital for successful implementation in textile finishing processes. To buy or purchase these specialized textile auxiliary agents, direct consultation with experienced chemical manufacturers and suppliers is recommended to ensure product suitability and obtain competitive pricing information.