A key snapping in a lock happens more often than you might think: fatigued metal in an old key, a poorly cut copy, or a frozen or dirty cylinder. The main thing is not to panic and not to force anything. Often you can get the broken piece out yourself in a few minutes, without calling a locksmith or replacing the lock.
Which method works depends on the type of lock, how deep the piece is stuck and how much time you have. Locks vary a lot, so you may need to try more than one approach. They are listed below from the simplest.
What you will need
Important: Do not push the broken piece further in, do not pull it sideways and never put glue in the lock. If the key still will not come out after trying everything, stop and call a locksmith to save the lock.
Step 1
Align the broken piece and pull it out
A key can only come out of the lock in the position it went in, with the cuts lined up with the top of the cylinder. If the key snapped while turning, gently return the cylinder to its starting position: sometimes the piece is stuck simply because the pins have not dropped back into place.
Once the piece is aligned and sticking out slightly, grip it firmly with needle-nose pliers and pull it straight towards you without jerking. If you have no pliers, tweezers will do, but be careful not to push the piece deeper.
Step 2
Lubricate the lock and wiggle the piece
Often the key catches on the pins because of dirt in the cylinder or a roughly cut copy. Aim the thin straw of WD-40 Multi-Use Smart Straw straight into the keyhole and give a short spray. It works its way between the pins and the broken piece and reduces friction. Keep a rag handy to catch any excess.
After a minute, grip the piece again and gently wiggle it up and down, not side to side, easing it out of the lock.
Step 3
Try the cold
If the piece will not budge, ice can help. Cold makes the metal contract slightly so the key slips out more easily. Wrap an ice cube in a paper towel to stop drips and press it against the broken piece and the lock barrel for a few minutes. Then try again, wiggling gently. Outdoors in winter this works less well, as the lock is already cold.
Step 4
Clean and lubricate the mechanism
Once the piece is out, do not leave the lock as it is: dust and metal shavings have built up inside and may have caused the break. Spray a little more WD-40 Multi-Use into the keyhole, then insert and remove the spare key several times, wiping it with a rag until no more dirt comes out.
Finally, treat the cylinder with WD-40 Specialist Dry PTFE spray: it leaves a thin dry film that does not attract dust and keeps the key turning smoothly. Give it a few minutes to dry and check the lock opens and closes properly.
Tip: To stop it happening again, lubricate entrance door locks with dry PTFE spray before winter and in spring, and replace any key that goes in stiffly or is already bent before it breaks. Always have copies cut from the original key, not from another copy.
What next
If nothing works, the problem may be in the mechanism itself, and it is better to call a locksmith than to damage the lock. For prevention, keep WD-40 Multi-Use at home: it is useful for locks, hinges and any mechanism that sticks.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
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