Duct tape or gaffer tape — which do I actually need?

The names are used interchangeably in shops and they are genuinely different products with different adhesives, different backings and different intended lives. Buying the wrong one is why a repair leaves a sticky mess on a painted surface, or why a tape that was supposed to hold outdoors let go in the first cold snap.

Step by step

1. Decide whether it will be removed.This is the question that separates them. Gaffer tape is designed to come off cleanly from most surfaces within a reasonable time. Duct tape is not, and the residue it leaves after a few weeks in warmth is genuinely difficult to remove.
2. Decide whether it will be seen.Gaffer tape has a matt, non-reflective finish and comes in colours including black that disappears under stage lighting. Duct tape is shiny and obvious.
3. Decide whether it has to keep water out.Duct tape's polyethylene coating makes it genuinely water-resistant, which is why it is the roadside-repair tape. Gaffer's cloth backing is not, and it goes soggy.
4. Accept that neither is a permanent repair.Both adhesives creep under load and degrade with heat, ultraviolet and time. A duct-taped repair that has been in place for a year has usually got worse, not settled in.
5. Never use duct tape on ducting.It fails on the temperature cycling of a real duct, which is a well-documented result. Aluminium foil tape is what ducting, flue joints and insulation seams need, and it is what the name misleadingly implies.
6. Never use either on a live electrical repair.Neither is an insulating tape, neither is rated for it, and a taped electrical joint is not an acceptable repair in any case. That needs a proper connector, and damaged fixed wiring needs an electrician.
7. Do not use either on paint, wallpaper or a finished surface.Both will pull the surface off, and duct tape reliably will. Low-tack decorator's tape is the product for anything decorated.
8. Check for a specific tape before defaulting to either.Self-amalgamating for a watertight wrap, foil for heat, PTFE for threads, exterior-grade cloth tape for outdoor bundling, double-sided foam for mounting. In almost every case the specific tape works far better and lasts far longer.

Tips

• Gaffer tape tears cleanly across and along by hand, which is why stage and film crews use it. Duct tape tears raggedly and often needs a knife.
• Both peel off far more cleanly if warmed gently with a hairdryer first, and pulled back on themselves at a shallow angle rather than straight out.
• Cold reduces the tack of both dramatically. Neither sticks well to a cold surface, and a repair made in the cold often lets go as soon as it is loaded.
• For outdoor use of any duration, look for a tape specifically rated for exterior use and ultraviolet. Ordinary duct tape degrades in sunlight within months.
• Residue from either responds to a citrus-based adhesive remover, white spirit or isopropyl alcohol — test on a hidden area first, because all three attack some finishes.

Common mistakes

• Using duct tape as a permanent fix — The adhesive creeps, degrades and turns into a sticky film that is far harder to remove than the original problem was to fix properly.
• Using either on ducting or a flue — They fail at duct temperatures. Foil tape is the correct product and it is a genuine safety point on a flue.
• Taping over a damaged cable — It is not an insulating repair, it hides the damage, and it does nothing about the fault. The cable needs replacing or a proper connector.
• Sticking either to a painted wall — It will take the paint off. Decorator's tape exists for anything decorated.

Questions people ask