Undercoating is necessary in many cases, but not always. It depends mainly on the fabric type and the performance requirements of the print.
When undercoating is necessary?
Undercoating is required when printing silicone ink on synthetic or difficult fabrics, such as:Polyester,Nylon,Waterproof fabrics,Blended fabrics (poly/cotton, nylon blends)
Why it's needed:
Improves adhesion between silicone ink and the fabric
Prevents peeling, cracking, or edge lifting
Enhances wash durability
Creates a stable base for HD, puff, glossy, or molding effects
Without undercoating, silicone ink may not bond properly and can fail after washing or stretching.
When undercoating is not necessary?
Undercoating can usually be skipped on:
Cotton fabrics
Natural fibers with good absorbency
Reason:
Cotton fibers allow silicone ink to anchor mechanically into the fabric, providing sufficient adhesion without an extra layer.
Performance-based considerations
Even on cotton, undercoating may still be recommended if:
You are doing high-density (HD) printing
You need extra durability for sportswear or workwear
You are printing on smooth or compact cotton
You want a perfect surface finish (sharp edges, even height)
Typical undercoating process
Print undercoating silicone ink (usually 1–2 passes)
Flash dry after each pass (heat gun or drying tunnel)
Print the top silicone layer (HD, puff, glossy, etc.)
Final heat curing
Summary
Necessary for polyester, nylon, waterproof, and blended fabrics
Optional for cotton, depending on print effect and durability needs
Not required for basic silicone printing on standard cotton
