Bought the Wrong Filament? 5 Simple Methods to Accurately Identify Nylon 6 vs. Nylon 66

They look alike, but their performance and cost are vastly different. Confusing Nylon 6 (PA6) with Nylon 66 (PA66) is a common and costly trap in industrial purchasing. This guide provides five methods, from professional tests to quick field checks, to help you make an informed choice and ensure every filament you procure is worth the price.

Why Does Accurate Identification Matter?

Choosing the wrong nylon isn't just a minor issue; it directly impacts your operations:

• Performance Failure: Using PA6 in a high-temperature application designed for PA66 will cause filaments to soften and deform, leading to production stoppages and defective products.
• Wasted Costs: Using more expensive PA66 in a general-purpose application where PA6 would suffice leads to unnecessary procurement expenses.
• Supplier Risk: An inability to differentiate makes you vulnerable to dishonest suppliers "substituting" a lower-grade material.

Core Differences at a Glance: PA6 vs. PA66

Before diving into the testing methods, this table gives you a quick overview of the key distinctions:

5 Practical Identification Methods

1. Heat Resistance Test

This is the most straightforward industrial-grade method. Place the filament in an environment at 150°C (302°F), such as an industrial oven. PA6 filaments will soften noticeably, while PA66 will maintain significant rigidity. This is because the melting point of PA66 (~265°C) is much higher than that of PA6 (~220°C).

2. Mechanical Feel & Bend Test

At room temperature, PA66 typically feels harder and stiffer. Try to bend the filament firmly. The one that exhibits stronger spring-back and resistance to bending is likely PA66. Its superior tensile strength and rigidity make it better suited for heavy-duty grinding and cleaning tasks.

3. Moisture Absorption Observation

After placing a sample in a humid environment (or briefly soaking it in water), observe the changes. PA6, with its higher water absorption rate, will become softer and show more significant dimensional swelling. In contrast, PA66 offers better dimensional stability and performance retention.

[Learn How Our High-Stability PA66 Filaments Solve Humidity-Related Issues]

4. The Burn Test (For Quick Field Checks Only)

Safety Warning: This test must be performed in a well-ventilated, safe area.
Ignite a small bundle of filaments and observe:

• Nylon 6 (PA6): The flame will be yellow at the top and blue at the base. It will melt and drip, producing an odor similar to burnt celery.
• Nylon 66 (PA66): The flame is often purely blue. It tends to melt with less dripping and gives off an odor more like burnt wool or fingernails.

5. Review Supplier Documentation (The Most Reliable Method)

This is the most professional and risk-free approach. Request a Technical Data Sheet (TDS), Certificate of Analysis, or material certification from your supplier. A reputable manufacturer will clearly label the material as "Polyamide 6" or "Polyamide 66." This is your ultimate guarantee of procurement accuracy.

Eliminate Purchasing Risks, Starting with Accurate Identification

Still worried about the true identity of your current filaments? Don't let uncertainty compromise your product quality and cost control.

Contact our material specialists today for a detailed PA6 vs. PA66 application matching guide. Or, send us your sample, and our technical team can provide a complimentary preliminary material identification service to ensure every dollar of your investment is maximized!