What is Stitched Chopped Strand Mat?

Stitched Chopped Strand Mat (SCSM) is a specialty glass fiber reinforcement material made by cutting continuous glass fiber strands into short lengths (typically ~50 mm), laying them randomly and uniformly flat, and stitching them together with polyester thread. Unlike standard chopped strand mats that rely on a resin binder, the stitching improves fiber stability and wet-out performance. Zhejiang Zhenshi New Material Co., Ltd. produces a corrosion-resistant stitched chopped strand mat widely used in composites manufacturing, especially where durability and process performance are critical.

What are the key characteristics of Stitched Chopped Strand Mat?

Answer: The stitched construction and random fiber distribution give SCSM a set of performance benefits for composite fabrication:

Fast resin impregnation — stitching helps resin flow quickly through the mat. 

Good toughness and uniform distribution — fibers are distributed consistently for predictable mechanical properties. 

Corrosion resistance and high compressive strength make it suitable for demanding environments. 

Flame retardant & environmentally friendly variants support broader industry standards. 

Easy to cut and shape — critical for complex molds and hand lay-up. 

These attributes help SCSM outperform traditional chopped mats in uniformity and structural consistency.

Which processes and industries commonly use SCSM?

Answer: Stitched chopped strand mat is versatile and compatible with various composite processes, especially those involving thermosetting resins such as unsaturated polyester, vinyl ester, and often epoxy. 

Main application methods include:

Hand lay-up — fast wet-out and ease of handling. 

Resin Transfer Molding (RTM) — uniform fiber distribution improves resin flow and part quality. 

Pultrusion and filament winding — stitching stabilizes fiber position for continuous processes. 

Key industries:

Marine & yacht manufacturing — hulls, decks, and pipes. 

Transportation & automotive — lightweight panels and structural parts. 

Infrastructure & chemical tanks — corrosion-resistant composite vessels. 

Pipes and pultruded products — strength retention in long profiles.

What are the correct steps for using SCSM in hand lay-up?

Answer: To achieve optimal results when using SCSM with resin systems:

Prepare the mold surface — clean and apply mold release to avoid adhesion issues.

Cut mat to fit contours — the stitched structure makes cutting easy without fraying. 

Apply resin gradually — saturate the mat thoroughly, ensuring full wet-out of fibers. 

Remove trapped air — use rollers to eliminate bubbles that weaken laminate integrity.

Cure at controlled conditions — follow resin manufacturer guidelines for temperature and time.

Proper penetration and layer compaction are essential for strong, void-free composite structures.

What are common problems encountered with SCSM, and how can they be solved?

Problem: Poor resin wet-out or incomplete saturation

Cause: Resin cured before fully penetrating the mat or trapped air pockets.

Solution:

Use adequate resin amounts and a low-viscosity system.

Roll into the mat repeatedly to release air and promote saturation.

Work in optimal temperature ranges to maintain resin flow.

Problem: Delamination or weak interlaminar bonding

Cause: Insufficient resin impregnation or mismatched resin type.

Solution:

Match the resin system (e.g., unsaturated polyester or epoxy) to the mat type.

Consider stitched variants when stronger interlaminar strength is needed. 

Ensure correct curing cycles to avoid weak interfaces.

Problem: Material distortion during placement

Cause: Improper placement or handling of stiff mats.

Solution:

Pre-cut to approximate shapes.

Use stitched mats with better flexibility and contouring for complex molds.

Problem: Resin incompatibility with binder

Cause: Standard chopped mats with binder issues (especially in epoxy systems).

Solution:

Choose stitched mats designed to work with your resin system — some products eliminate binder reliance and improve compatibility.

How does Zhejiang Zhenshi’s product stand out in the market?

Answer: Zhejiang Zhenshi New Material Co., Ltd.’s stitched chopped strand mat combines rapid impregnation, uniform fiber structure, good mechanical properties, and chemical resistance, making it a strong choice for composites manufacturers targeting quality and reliability. 

Common specifications (e.g., E-MK300 to E-MK900) reflect flexibility in grammage and thickness selection, allowing engineers to tailor materials to specific load and performance requirements.

Conclusion

Stitched chopped strand mat — notably from companies like Zhejiang Zhenshi — continues to gain traction due to its enhanced wet-out performance, improved structural consistency, and broad process compatibility. These features make it a core reinforcement choice in sectors ranging from marine and automotive to pultrusion and RTM composites.