Can Polyester Thread Go In The Microwave? [The SURPRISING Answer]

Originally Created on: May 10, 2023 @ 9:42 am

Can polyester thread go in the microwave? Medium-weight polyester threads are the preferred choice for many sewers. Not only are the threads ideal for garment sewing and bag sewing.

But you can do so much more with polyester thread. For example, you recently bought a microwave and you want to heat food in your Pyrex bowl.

However, the Pyrex bowl does not have handles. Since you have sewing skills, you decide to make a pouch or cozy that will enable you to handle the hot bowl.

The problem is you’re worried about using polyester thread for the pouch. So, you’re probably asking yourself, can polyester thread go in the microwave?

Well, you’re not alone. The majority of sewers often wonder if a polyester thread is microwave safe.

To set the record straight, we researched, and here is what we uncovered about polyester threads and their use in microwaves.

Table of Content

Can Polyester Thread Go in the Microwave?

It’s not recommended to microwave polyester thread. This is because polyester is a manufactured synthetic fiber. It’s a kind of plastic derived from petroleum.

While polyester is stronger than cotton due to its chemical makeup and ability to stretch, it heats up quickly when placed in a microwave.

Heating polyester thread can cause fire or electric shock. Yes, polyester fabrics are highly flame resistant which means it requires a lot of heat for the fabric to form flames.

Due to this, polyester thread and fabrics are the best materials for making children’s sleepwear.

However, when you microwave a polyester thread, the heat will melt the thread. If you microwave polyester thread with other materials like plastic or metal, it can spark. This will create a dangerous electric shock hazard.

What Thread Is Microwave Safe?

Different types of threads are microwave safe but most people often worry about fabrics made from these threads. What you ought to know is that most threads and fabrics are safe for use in a microwave oven.

However, you’ve to follow the manufacturer’s instructions.

One of the materials that’s microwave-safe is cotton. However, you need to use 100% cotton thread or 100% wool. You also have mercerized cotton thread.

This is a type of thread that’s been treated with a caustic soda solution. In the end, what you have is a type of thread with a high degree of strength and luster.

So, if you’re planning on crocheting a microwave cozy for your Pyrex glass bowl that does have handles, we recommend using 100% cotton or 100% wool thread.

Using polyester thread is not recommended. As aforementioned, polyester thread melts when exposed to heat.

Is Polyester Thread Flammable?

Standard polyester threads are combustible. Once ignited, severe melting and dripping will occur. However, they are slow to ignite.

This is because polyester threads are naturally flame-retardant. That is why they melt when exposed to a high temperature.

What you ought to know is that the degree of flammability of polyester thread depends on the specific manufacturing process. Some polyester threads are usually treated with flame retardants while others are not.

As such, flame-retardant polyester threads are less likely to ignite.

Can You Melt Polyester Thread?

The melting point of polyester is 250 degrees C to 265 degrees C. So, when you expose polyester thread to heat even from a hot iron, it will melt.

Research reveals that polyester ignites at roughly 440 degrees Celsius. Once it ignites, the thread will drip but may self-extinguish.

As aforementioned, some manufacturers treat polyester threads with fire-retardant solutions.

While this may slow down the melting of polyester thread, if exposed to high temperatures, it will ignite. This is because fire retardant is not fireproof.

At What Temperature Will Polyester Thread Melt?

As aforementioned, polyester threads melt at 240 to 260 degrees Celcius or 480 degrees F. However, it’s heat-resistant and iron safe especially if you follow manufacturer instructions.

This is unlike nylon which starts to yellow at 350 degrees F and starts to melt at about 415 degrees F.

Still, it’s always recommended to be watchful of your clothes when close to open flames or fires since polyester is not fireproof.

Conclusion

To sum it up, can polyester thread go in the microwave? Well, it’s not safe to place the polyester thread in the microwave.

As aforementioned, polyester is fire resistant but not fireproof. If exposed to heat, it will slowly ignite.

So, we recommend that you do not put a polyester thread in your microwave.