Demystifying Fiberglass Peel Ply and Release Fabric: Types and Uses Unveiled

Demystifying Fiberglass Peel Ply and Release Fabric: Types and Uses Unveiled


In this post I will explain briefly the basic differences of Peel Ply and their applications.  I use it often when constructing my fiberglass lids to achieve a smooth surface on the bottom allowing the customer to finish them with very little work.  I also use it when hand laminating a surface that I know will be faired smooth and top coated saving hours of sanding work and money on fairing putty.

There are many different types of peel ply and you should consult with your supplier to be sure you are using the correct type for your project. A few extra dollars spent on peel ply will save you tons of labor later! 

Fiberglass peel ply and release fabric play crucial roles in composite manufacturing processes, serving as essential components in achieving high-quality and durable composite structures. These materials are designed to facilitate the fabrication process, ensuring optimal bonding, surface finish, and ease of demolding. In this blog post, we'll delve into the differences between various types of fiberglass peel ply and release fabric, as well as their diverse applications in composite manufacturing.

Understanding Fiberglass Peel Ply:

1. **Definition:**
Fiberglass peel ply is a lightweight, woven fabric made from materials like fiberglass, nylon, or polyester. It is applied directly to the surface of a composite layup before the curing process.

2. **Purpose:**
The primary purpose of peel ply is to create a textured surface on the composite, promoting better adhesion between layers. It also serves as a sacrificial layer, allowing for easy removal of excess resin and providing a clean surface for subsequent bonding or finishing.

3. **Types:**
- **Nylon Peel Ply:** Offers a good balance between strength and porosity, facilitating resin removal.
- **Polyester Peel Ply:** Resistant to high temperatures, making it suitable for curing processes that involve elevated temperatures.

Understanding Release Fabric:

1. **Definition:**
Release fabric, often referred to as release film or parting film, is a non-permeable material used to cover the composite layup during the curing process.

2. **Purpose:**
Release fabric prevents the composite from bonding to other surfaces during curing. It acts as a barrier, ensuring that the composite can be easily demolded without sticking to the mold or any auxiliary materials.

3. **Types:**
- **Polytetrafluoroethylene (PTFE) Release Fabric:** Known for its non-stick properties, PTFE release fabric is widely used in high-temperature curing processes.
- **Silicone Release Fabric:** Offers good release properties and is often used in lower temperature applications.


1. **Aerospace Industry:**
Fiberglass peel ply and release fabric find extensive use in aerospace applications, where lightweight and high-strength composites are crucial for aircraft components.

2. **Wind Energy:**
In the production of wind turbine blades, these materials aid in creating strong and durable composite structures that can withstand harsh environmental conditions.

3. **Marine Industry:**
Fiberglass peel ply and release fabric are employed in boat manufacturing, ensuring a smooth and well-bonded surface finish for hulls and other components.

4. **Automotive Sector:**
Composite materials are increasingly used in automotive manufacturing, and peel ply/release fabric contribute to the production of lightweight and fuel-efficient components.

Peel ply, also known as Release Fabric, plays a vital role in the composite industry, contributing to the achievement of consistent and high-quality surface finishes. This essential material is typically applied after all fabric layers have been laid up, offering benefits in terms of surface texture, resin removal, and secondary bonding processes. In this discussion, we'll explore the different types of peel ply and delve into best practices for optimal utilization.

Types of Peel Ply:

1. **Porous vs. Non-Porous:**
- *Porous Peel Ply:* Enables the part to "breathe" during the cure process, allowing excess resin and volatiles to escape. Ideal for vacuum-assisted processes, it helps control resin content and eliminates potential defects.
- *Non-Porous Peel Ply:* Provides a glossy surface finish as it does not allow resin to be pulled from the part during cure. Careful application is crucial to prevent air and resin entrapment.

2. **Coated vs. Non-Coated:**
- *Non-Coated Peel Ply:* Primarily used for texturing laminate surfaces. While removal may require patience, it ensures no release agent residue is left on the cured laminate, reducing the risk of contaminants in secondary bonding.
- *Coated Peel Ply:* Treated with release agents like silicone or Teflon for easy removal post-cure. Caution is advised during secondary bonding to eliminate any residual release agents that might affect the bonding process.

Best Practices for Peel Ply Use:

1. **Tools for Removal:**
- Dental pick sets and razor blades are effective tools for removing sticky peel ply. Care must be taken to avoid damaging underlying plies during the removal process.

2. **Extension Beyond Lay-Up Surfaces:**
- Extending peel ply beyond lay-up surfaces by an inch or more facilitates effective removal, ensuring a clean and uniform finish.

3. **Air Bubble Removal:**
- Eliminate air bubbles between the peel ply and fabric surface to enhance the effectiveness of the peel ply.

4. **Avoid Bridging in Complex Contours:**
- Exercise caution to prevent peel ply from being bridged in female radii or complex contours, as this can lead to quality issues with bagging and inadequate pressure on the part surface.

5. **Use Multiple Pieces as Needed:**
- While a single piece may suffice for simple laminates, using multiple pieces may ease the removal process, especially on more intricate structures.

6. **Consider Weave Tightness:**
- Tighter weaves often result in finer surface finishes but may pose challenges in draping over complex contours.

7. **Surface Preparation:**
- Despite claims of minimal sanding needed for secondary bonding, it is advisable to follow best practices for surface preparation to ensure a thoroughly clean bonding surface, free from any traces of peel ply remnants.

Fiberglass peel ply and release fabric are indispensable tools in the composite manufacturing toolkit, contributing to the production of high-performance, lightweight, and durable materials across various industries. Understanding the differences between these materials and their applications is crucial for achieving optimal results in composite fabrication processes. Whether in aerospace, wind energy, marine, or automotive applications, the careful selection and proper use of these materials play a key role in the success of composite manufacturing projects.