Don't Leave Your Filament in Your Car: Here's Why It Matters

Jun 27
2 min read

One of the most common mistakes 3D printing users make is leaving filament or printed parts inside a hot vehicle. While it may seem harmless, heat can significantly damage filament and affect print quality later.

Understanding how temperature affects different materials can help you avoid wasted filament and failed prints.

🌡️ What Happens Inside a Hot Car

A parked car can reach extremely high temperatures—often much hotter than people expect. Even on a mild day, the inside of a vehicle can become hot enough to soften certain plastics.

When filament is exposed to heat:

It can absorb moisture more quickly
It may soften or deform slightly on the spool
It can become brittle or inconsistent when printed
It may cause feeding issues or clogging later

⚠️ Why PLA Is the Most Sensitive

PLA is the most commonly used filament, but it has the lowest heat resistance.

In a hot car:

PLA can soften quickly
Spools may warp slightly
Prints made from PLA can fail if used in hot environments

This is why PLA is best used for indoor, non-heat-exposed projects.

🔧 PETG, ABS, and ASA Handle Heat Better

Other materials perform much better in warm environments:

PETG – More heat resistant than PLA, good for general use and some outdoor applications
ABS – Strong and heat resistant, but can degrade with UV exposure
ASA – Best option for outdoor and high-heat environments due to UV and weather resistance
Carbon Fiber PETG – More rigid and stable under heat than standard PETG

These materials are better suited for parts that may be exposed to heat or used in real-world conditions.

🚗 Why Cars Are a Risk for Filament

Even if filament is only left in a car for a short time, repeated heat cycles can slowly degrade it.

The biggest risks include:

Spool deformation (making it hard to feed into printers)
Moisture absorption (affecting print quality)
Material weakening over time
Inconsistent extrusion during printing

🧠 Best Practice for Storage

To keep filament in good condition:

Store it indoors at room temperature
Keep it in sealed bags or containers when possible
Avoid leaving it in vehicles, garages without climate control, or direct sunlight
Use desiccant packs to reduce moisture exposure

📍 Final Thoughts

3D printer filament is sensitive to temperature and storage conditions. A simple mistake—like leaving it in a hot car—can affect your print quality later.

By storing filament properly, you ensure: