How to Weld Plastic with a Soldering Iron

Learn DIY plastic welding with a soldering iron*

When the plastic casing of an object gets cracked or broken into pieces, most people just buy a new one. However, plastic is remarkably malleable and quite easy to melt and reattach with a soldering iron. Although the repaired object will not look exactly as it did when it was new, with practice you can make smooth plastic welds that are not cosmetically obvious.

Using your soldering iron or soldering station to weld plastic is not limited to repairs: you can weld plastic for fabrication and even artistic purposes. You do not need to go out and buy a plastic welding kit if you already own a soldering iron or station — you can begin welding plastic today. Let’s take a look at the process.

Before You Start

When you use equipment for anything other than what was meant for, it’s important to take precautions and be aware of the risks. We recommend using a different soldering tip for plastic welding to avoid damaging iron tips that you use for actual soldering. 

Additionally, welding plastic indoors is health hazard if the area isn’t properly ventilated to disperse fumes. For that reason, we recommend using a fume extractor or soldering outdoors or in a well-ventilated area. 

How to Melt Plastic Together with a Soldering Iron

(Note: Before you try your first weld, you may want to experiment and practice on scrap plastic to learn how long you will need to press the soldering iron on particular points in the plastic.)

1. Prepare your workstation. 

Choose a well-ventilated area to set up your soldering station. Turn on a smoke absorber or open windows and set out fans, if necessary. To better protect yourself from fumes or burns, consider wearing long sleeves, heat-resistant gloves, safety glasses, and a dust mask.

2. Prepare the plastic.

Begin by thoroughly cleaning the plastic with soap and degreaser, even if it does not appear to be dirty. Sand the edges of the plastic down so that they are not jagged. 

3. Power the soldering iron.

Next, you will plug in the soldering iron and give it enough time to warm up, which should only take a few minutes. If possible, opt for a soldering iron with a digital temperature display and temperature control. We also recommend using a separate soldering tip for plastic welding. 

4. Combine and carefully melt the plastic pieces with the soldering tip. 

Push the two pieces of plastic together and hold them there while you run the soldering iron tip along the seam until the two pieces of plastic are partially melted together. While the pieces of plastic are still hot and movable, adjust them so that they fit together as best as you can manage.

5. Use additional plastic, if necessary. 

You can strengthen the weld by adding small pieces of plastic — ideally thin strips — to the seam. Then fully melt these pieces of plastic by pressing them with the soldering iron tip until they are liquefied. Distribute the liquefied plastic smoothly along the length of the seam with a soldering iron tip.

6. Smooth the melted seam of plastic. 

The last step is to go over the seam and the plastic surrounding it with the soldering iron using swift, smooth strokes. Once you have some practice with this technique, you should be able create an even, smooth plastic weld.

Best Soldering Irons for Plastic Welding

While you can go to the store and purchase a plastic welding iron, a soldering iron can be used for a variety of other purposes in addition to welding plastic together! The following are some of our favorite multipurpose soldering stations:

CSI-PREMIER-110W Modular Soldering Station

This multifunctional soldering station includes multiple soldering tips and 4 programmable temperature settings. That way, you can reserve one soldering tip for plastic welding, program the desired temperature,  and save temperature settings for later. The station comes with a variety of other useful features, like a modular removable soldering stand, helping hands, a LED magnifying glass, and more!

HS-01-BUNDLE6 Smart 65W Soldering Iron - Includes Temp Control and 6 Tips

For quicker, on-the-go jobs that still require precision temperature control and multiple soldering tip options, look no further than the Smart 65W Soldering Iron! This sleek, highly portable soldering iron features a built-in OLED temperature display, adjustable temperature settings, and 6 different kinds of soldering tips. 

 CSI-PREMIER-PRO Rework and Soldering Station

The CSI-PREMIER-PRO is an incredibly versatile hot air rework station and soldering station. In addition to a soldering iron, the unit includes a hot air gun for SMD soldering or solder repairs. The hot air gun can be a useful, although somewhat trickier, alternative to using a soldering iron for plastic welding, because the plastic does not touch the nozzle. This unit also has temperature control and display. 

*Disclaimer: Please be aware of the risks and proceed with caution when using soldering equipment for purposes other than its designed use. Plastic may damage soldering tips or give off toxic fumes.