Shrink wrap tubing 101: Why you should be using this versatile repair material

While insulating tape (the 3M Scotch Super 33+ is the best) and even liquid electrical tape (I’ve had best success with the Permatex brand) have their place in a modern tech repair toolkit, shrink wrap tubing beats them both in terms of both versatility and creating a lasting repair.

These thermoplastic tubes shrink when heated for a snug fit, creating a tight protective layer around the wires that can last for years.

Also: You’re using super glue all wrong

Not only does it insulate and protect wires, but shrink wrap tubing can also add strain relief to cables, bundle cables together tidily, and even allow for easy cable marking.

Different types of heat shrink tubing

To get the most out of your shrink wrap tubing, it’s essential to understand the different types, select the right one for your needs, and apply it correctly. With these tips, you’ll be able to tackle any repair project with confidence and ease.

Shrink ratio

When buying shrink wrap tubing, it’s essential to consider two features: the shrink ratio and the intended use.

The shrink ratio refers to the difference between the original size of the tube and the size it can shrink down to after heat is applied. Common shrink ratios are 2:1, 3:1, and 4:1, with higher numbers indicating a greater ratio and more significant shrinkage.

Also: Why I replaced my $40 multimeter with these smart measuring tools

While 2:1 tubing is suitable for basic repairs, I recommend going for higher ratios, such as 3:1 or 4:1, for their versatility. These higher ratios allow the heat shrink to fit over connectors (because the tubing starts out at a bigger diameter than the final diameter after shrinking) while still being able to shrink down onto cables for a secure seal.

However, if you’re looking for heat shrink tubing for labeling cables, you might want to consider a specialty product made for that purpose. For example, some industrial label makers, like the Brother PTE300, can print on special rolls of heat shrink tubing specifically designed to make tidy cable markers.

Single or dual wall?

Heat shrink tubing comes in two basic types — single or dual wall, also known as thin or double wall.

• Single or thin wall tubing: A good choice when electrical insulation or protection against abrasion and strain is required.
• Double or dual wall tubing: This tubing takes protection to the next level thanks to an additional adhesive layer inside the tube, which glues the tube in place and is ideal for situations where moisture or vibration may be a concern.

Other considerations

But there’s more. Along with shrink ratio and single/dual wall tubing, heat shrink tubing comes in a variety of different diameters, different colors – even transparent – and can be sold as rolls or as pre-cut lengths.

So, what should you buy?

OK, time to simplify things!

Also: How to pick the perfect hot glue gun

My recommendation is to get a kit containing a selection of dual wall, 4:1 heat shrink tubing, such as this 190-piece kit by Wirefy.

If you’ll be dealing with wires and cables thinner than 1.5 mm that this kit can accommodate, then you can also get a 275-piece 3:1 dual wall heat shrink tubing kit that can shrink down to under 1 mm.

Both these kits are weatherproof and waterproof, resistant to chemical attack, flame retardant, and rated to handle voltages up to 600V, making them suitable for a variety of different applications, from automotive, marine, and domestic repairs.

Also: This stuff is better than super glue

If you’re going to be using a lot of a certain size of tubing, then buying it by the roll is more cost-effective, but most of us aren’t going to need 50 feet of heat shrink tubing!

How to apply heat shrink tubing

OK, you’ve got your tubing, here’s how to apply it. 

Here I’m going to add some heat shrink tubing as strain relief for a charging cable.

1. Safety first!

We’re using heat here, and with that comes the risk of burns, melting things, and setting things — even yourself — on fire.

Also: Do you have a fire extinguisher? You should

Take care, work in an area where you’re away from flammable materials, and it’s preferable to work on a heat/flame resistant surface, such as a silicone or carbon fiber mat.

2. Clean the surface

Next, make sure that the surface you are applying the heat shrink tubing to is clean and dry and free from grease and oil.

3. Pick the right tube

This one is too small:

This one will work fine:

4. Heating the heat shrink tubing

Here you have a couple of options.

You can use a naked flame, but fire being fire, this comes with the risk of setting things — such as your work piece, or even yourself — alight. If you’re going to use a flame, keep it a good distance away from the tubing, and work carefully.

A safer choice is to use a hot air gun, such as this one that’s part of my Yihua 8786D soldering station. This is a lot safer and much easier to control than using a naked flame — but there is still a risk of burns, so be smart with it!

Apply the heat to the tubing, slowly shrinking it to fit onto the cable and connector. Take your time and work slowly, applying the heat evenly and taking care not to damage anything (or yourself!).

5. Done!

You can tell when you’re done when the heat shrink has evenly shrunk around the surface and the glue has oozed out of the ends, guaranteeing a good seal.

This 4:1 shrink ratio tubing has handled forming to cover both the connector and cable, despite the dramatic difference in diameter between the two.