Which material should you use for heat shrink tubing?
Heat shrink materials are available in a variety of materials, each with its own characteristics for use. By understanding their differences, you can choose the heat shrink tubing that best suits your needs.
Polyolefin
Polyolefin heat shrink tubing is one of the most popular, and for good reason. It can withstand temperatures up to 125-135°C (257-275°F) and shrinks quickly. In addition, it is durable, highly flame retardant and flexible.
Keep in mind that some polyolefin heat shrink tubing should not be used outdoors because UV light can degrade certain pigments. Black polyolefin heat shrink tubing is always safe in the sun.
Less Common Materials
Flexible heat shrink tubing stands out for its flexibility, even at temperatures as low as -75°C (-103°F). It is resistant to hazardous fluids such as diesel, gasoline and hydraulic fluids. It also has good abrasion resistance.
PVDF (polyvinylidene fluoride) heat shrink tubing is a good choice if you are looking for heat shrink tubing that can resist flames or other high temperatures. Some of its other advantages are resistance to corrosive chemicals, fuels and perforations.
Silicone heat shrink tubing is both flexible and resistant to temperature extremes. Because it performs well in a variety of sterilization methods, it is often the first choice for medical device insulation.
PTFE (polytetrafluoroethylene/Teflon) heat shrink tubing is non-reactive and therefore highly resistant to chemicals. Its low coefficient of friction makes it very slippery and it has a wide operating temperature range of -55 to 175°C (-67 to 347°F).
FEP (fluorinated ethylene propylene) heat shrink tubing is very similar to PTFE in terms of chemical resistance. However, it shrinks at lower temperatures and is somewhat less expensive.
Viton heat shrink tubing is a popular choice for hydraulic equipment. It is flexible, chemically resistant, and forms a good sealing barrier against a variety of fluids.
Special types of heat shrink tubing
Certain types of heat shrink tubing, such as marine grade or welded seal heat shrink tubing, are available for special applications. I have selected the most popular types below.
Double Wall Heat Shrink Tubing with Adhesive
Glued heat shrink tubing, also known as marine grade heat shrink tubing, consists of two layers. The outer layer is usually made of polyolefin, while the inner layer consists of a fusible adhesive.
When the adhesive-lined tube is heated, the adhesive melts as the outer layer shrinks. As a result, the adhesive flows into the small remaining cavity between the heat shrink tube and the object being sealed.
After the pipe and adhesive have cooled, the end result is a watertight seal. Ideal for boats (hence the term "marine grade"), automobiles or hobby RC projects where splashing is a frequent occurrence.
Marine grade heat shrink tubing typically has a higher shrinkage ratio (3:1 or higher) than regular heat shrink tubing. This allows for an extra tight fit that would be difficult to achieve using tubing that is only reduced to half the size (2:1).
For waterproof connectors and wires, this type of heat shrink is one of the best solutions. It is also more resistant to stretching and vibration than regular heat shrink and has a higher tensile strength.
Heat Shrink Butt Connectors - Heat Shrink Medium Tube
Heat shrink butt connectors (also known as solder seal wire connectors or heat shrink medium tubing) are a quick and easy way to solder and seal wires without the need for a soldering iron or other soldering equipment.
They consist of an outer layer of heat-shrink tubing with a section of solder inside. When heated, the solder melts and forms a solder joint on the wire inside the connector. The outer layer of the tube shrinks at the same time, sealing the connection in the process.
Top view of a box with a solder-sealed butt connector.
Like marine grade heat shrink tubing, heat shrink butt connectors typically come with a heat activated sealant for water resistance.
Solder-sealed wire connectors are ideal for connecting wires in hard-to-reach areas where soldering is not possible, or for emergency repairs where tool access is limited.
Clear Tubing
While most heat shrink tubing is black or colored, it is also available in clear variants. Clear heat shrink is most practical for checking connections after shrinkage.
The heat shrink butt connector mentioned above is almost always clear because it allows you to check the quality of the solder joint after shrinkage.
Clear heat shrink is also a good choice if your project has certain aesthetic needs.
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