Introduction

In Direct-to-Film (DTF) printing, the choice of hot melt adhesive powder plays a pivotal role in determining the final print’s quality, durability, and feel. While inks and films often receive much of the attention, the adhesive layer is the hidden engine that drives adhesion, flexibility, and wash resistance. At Jinlong, years of material science research have shown that the particle size distribution of hot melt powder—coarse vs. fine—can drastically alter performance outcomes.

This article provides a structured, scientific analysis of DTF hot melt powders, explaining their fundamental differences and helping business owners, technicians, and distributors make informed choices based on their application needs.

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Section 1: Understanding the Basics

DTF hot melt powders are typically based on thermoplastic polyurethane (TPU), chosen for its balance of flexibility, adhesion, and wash durability. When applied to a printed film, these powders melt under controlled heat, bond to textile fibers, and solidify into a durable adhesive layer.

The key variable here is particle size:

• Fine powders (e.g., 60–100 μm) distribute evenly, melt quickly, and form thin adhesive layers.
• Coarse powders (e.g., 100–250 μm or more) create thicker, stronger adhesive bonds with deeper penetration into fibers.

Particle size thus influences melt behavior, tactile feel, breathability, and durability—all critical for end-use performance.

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Section 2: The Profile of Coarse Powder (1#, 2#, and Black Powder)

General Characteristics of Coarse Powders

Particle Size Range: 100–250 μm (Jinlong 1# Powder, 2# Powder, Black Powder)

Coarse DTF hot melt powders are defined by their larger particle sizes and slower melting behavior compared to fine powders. When heat is applied, these particles create thicker adhesive layers that penetrate deeper into textile fibers, forming strong, durable bonds.

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1# Powder (120–170 μm) – Balanced Strength and Flexibility

Features:

• Moderate Particle Size: Positioned in the lower-to-mid range of coarse powders, it balances adhesion strength and usability.
• Good Flowability: Spreads evenly during shaking, reducing uneven coverage or clumping.
• Consistent Fusion: Melts into a firm adhesive layer while avoiding excessive rigidity.

Advantages:

• Provides strong adhesion without overly compromising softness.
• Works well on cotton and cotton blends, where medium bond strength is sufficient.
• Suitable for medium-sized graphics or logos where detail clarity and durability must coexist.

Limitations:

• May not provide enough anchoring for very heavy fabrics like canvas or denim.
• Slightly less soft than fine powders on lightweight garments.

Best Applications:

• Fashion T-shirts
• Polo shirts
• Casual cotton wear

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2# Powder (100–200 μm) – Heavy-Duty Performance

Features:

• Wider Particle Range: Covers small coarse particles up to larger granules, ensuring versatile bonding strength.
• Strong Adhesion: Designed for tough, dense, or textured fabrics where deep penetration is required.
• High Durability: Excels in resisting mechanical stress during repeated washing or stretching.

Advantages:

• Outstanding wash resistance, making it ideal for uniforms and outdoor wear.
• Provides deep fiber penetration, ensuring secure bonding on rougher textiles.
• Efficient for large solid color blocks due to reduced powder migration.

Limitations:

• Stiffer hand feel, especially on thin fabrics.
• Not suitable for fine lines or delicate prints.

Best Applications:

• Workwear and uniforms
• Canvas bags
• Hoodies and sweatshirts
• Denim jackets

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Black Powder (106–250 μm) – Specialized Anti-Sublimation Solution

Features:

• Dark Barrier Layer: Black pigmentation forms a blocking shield during heat pressing.
• Anti-Sublimation Function: Prevents dye migration (bleeding) from polyester or sublimated fabrics into the print layer.
• Retains Strength: Offers the same high adhesion and durability as standard coarse powders.

Advantages:

• Color Stability: Ensures printed designs remain sharp, with no background color contamination.
• Durability: Maintains wash resistance while acting as a protective barrier.
• Essential for Polyester: Solves a common problem in sportswear and sublimation-heavy textiles.

Limitations:

• Slightly less soft hand feel compared to fine powders.
• Dark base layer may be noticeable under very light or transparent prints.

Best Applications:

• Sports jerseys (polyester)
• Sublimated fabrics
• Custom fashion items requiring anti-bleed protection

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Section 3: The Profile of Fine Powder

Particle Size Range: 60–100 μm (Jinlong Super Powder)

Advantages:

• Soft Hand Feel: Thin, even adhesive layers preserve the comfort and drape of textiles.
• High Precision: Fine powders excel in sharp details, small lettering, and delicate linework.
• Breathability: Allows air permeability, making it ideal for sportswear and children’s clothing.

Limitations:

• Lower Bond Strength on Heavy Fabrics: Fine powders may not provide enough anchoring power on coarse textiles.
• Higher Material Cost per Area: More powder may be needed to achieve strong adhesion on large solid fills.

Best Applications:

• High-elasticity fabrics (spandex, Lycra blends)
• Baby and kids’ apparel
• Fashion T-shirts with intricate graphics

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Section 4: Head-to-Head Comparison

Property	1# Powder (120–170 μm)	2# Powder (100–200 μm)	Black Powder (106–250 μm)	Fine Powder (60–100 μm)
Adhesion Strength	Medium-strong	Very strong (deep penetration)	Very strong + Anti-sublimation	Moderate, surface-level adhesion
Hand Feel (Softness)	Balanced softness	Stiffer, bulkier	Stiff, protective layer	Soft, natural drape
Precision in Designs	Good for medium graphics	Limited for fine details	Limited, focus on protection	Excellent for small text & fine lines
Breathability	Moderate	Low	Low	High
Wash Durability	High	Very high	Very high + Color stability	High, but less durable on thick fabrics
Ideal Fabrics	Cotton, cotton blends	Canvas, denim, heavy cotton	Polyester, sublimated fabrics	Spandex, Lycra, babywear, fashion tees

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Conclusion

Choosing between coarse and fine DTF hot melt powders is not about which is universally “better,” but rather which is better suited to the job at hand.

• 1# Powder is ideal for those seeking balanced adhesion and softness, especially in casual cotton wear.
• 2# Powder excels in heavy-duty applications where durability is paramount.
• Black Powder offers a unique anti-sublimation barrier, protecting prints on polyester and sublimated fabrics.
• Fine Powder provides superior softness and detail precision, perfect for delicate or high-stretch fabrics.

At Jinlong, our research and product portfolio—from Super Soft Fine Powder (60–100 μm) to high-strength Coarse Powders (1#, 2#, Black Powder)—are designed to empower printers with the right solution for every application. By understanding the science of powder particle size, you can optimize production outcomes, reduce rework, and deliver products that meet your customers’ expectations.