Electronics & Appliance Repair
Heat Shrink, Electrical Tape and Hot Glue: Insulating and Securing Repairs
When to use heat shrink tubing, electrical tape, self-amalgamating tape, hot glue and Kapton tape in repairs, how to size heat shrink, and how to apply each correctly.
After you have soldered a joint or repaired a cable, it needs insulation and strain relief. The three workhorses are heat shrink tubing, electrical tape and hot glue, with a few specialist tapes for specific jobs. Choosing the right one makes repairs safer and longer-lasting.
Quick answer
- Heat shrink tubing: the best insulation for wire joints; neat and durable.
- Electrical (PVC) tape: quick insulation and bundling; can loosen over time with heat.
- Self-amalgamating tape: fuses to itself; waterproof seals.
- Kapton (polyimide) tape: high-temperature insulation inside electronics.
- Hot glue: strain relief, securing wires and parts; not for hot components.
Heat shrink tubing
Choosing size and ratio
- Shrink ratio: 2:1 is standard (shrinks to half its diameter); 3:1 and 4:1 cover larger size differences (e.g. over connectors).
- Size: choose tubing whose expanded diameter slides over the joint and whose recovered (shrunk) diameter is smaller than the wire.
- Adhesive-lined (dual wall): melts inside to seal against moisture; great for car and outdoor wiring.
- Length: extend at least 5–10 mm past the joint on each side.
How to apply it
- Slide the tubing onto the wire before soldering (the most commonly forgotten step).
- After the joint cools, centre the tubing over it.
- Heat evenly with a heat gun on low/medium or a hot-air station, rotating around it. Start in the middle and work outwards to push out air.
- Stop when it conforms tightly. A lighter works in an emergency but tends to scorch and leave soot.
Electrical tape
- Use quality vinyl tape rated for electrical insulation.
- Stretch it slightly and overlap by half the width.
- Finish without stretching the last turn, so it does not "flag" (unravel).
- Good for temporary repairs, bundling and colour coding. For permanent joints, heat shrink is better.
Other useful tapes
| Tape | Use |
|---|---|
| Self-amalgamating (silicone or rubber) | Waterproofing, hoses, outdoor connections, emergency repairs |
| Kapton (polyimide) | High-temperature insulation, masking boards during soldering or hot air |
| Cloth (fabric) harness tape | Car wiring looms; reduces rattles |
| Aluminium tape | Shielding, heat reflection |
| Double-sided foam tape | Mounting small modules |
Hot glue
A hot glue gun is handy for strain relief at cable entry points, securing loose wires and connectors, and fixing lightweight parts. Limitations:
- It softens at around 60–100°C (depending on the glue), so do not use it on hot components such as power resistors, regulators or near heaters.
- It is hard to remove cleanly; isopropyl alcohol can help release it from some surfaces.
- Low-temperature guns are safer around delicate parts and for crafts; high-temperature guns bond better.
For structural bonds, use epoxy; for electronics potting, use specific potting compounds; for sealing, use neutral-cure silicone (acetoxy silicone smells of vinegar and can corrode electronics).
Frequently asked questions
Is electrical tape as good as heat shrink?
For permanent joints, no. Heat shrink does not unravel, resists abrasion and looks neater. Tape is fine for temporary repairs.
Can I use a hair dryer to shrink heat shrink tubing?
Most hair dryers are not hot enough. Use a heat gun or hot-air rework station.
This guide is general information, not professional advice. Always read your tool's manual, use the right protective equipment and follow local building and electrical codes. See our disclaimer.