How to Untangle and Fix Aluminium Venetian Blind Cords

Tangled aluminium venetian blind cords are almost always caused by the same things, lowering the blind at an angle, pulling cords unevenly, or letting the blind drop too fast. It looks worse than it is.

Most tangles can be sorted in under ten minutes without any tools.

What You’ll Need

Tools

• Flathead screwdriver (small)
• Needle or safety pin (for tight knots)
• Scissors (only if trimming a frayed cord end)

Materials / Replacement Parts

• Replacement lift cord (3mm round cord), only needed if the existing cord is broken or badly frayed
• Cord connector/repair clip, for joining two sections
• Blind cord weight or tassel (if the original is missing)

---

How to Fix It: Step-by-Step

Step 1: Lower the Blind and Assess the Problem

Drop the blind to its full length before you touch anything. Trying to work on a tangled cord while the blind is half-raised makes it harder, not easier.

1. Pull the lift cords gently to lower the blind completely
2. Look at where the tangle starts: is it near the headrail, mid-blind, or at the bottom rail?
3. Check whether the cord is tangled between slats, kinked at the pulley, or knotted outside the blind
4. If the cord has snapped rather than tangled, skip to Step 4

The location of the problem tells you exactly how much work you’re in for.

Step 2: Separate and Loosen the Tangle

Work slowly here. Aluminium slats bend easily and a bent slat is a separate problem you don’t want to create.

1. Lay the blind as flat as possible. If it’s a window-mounted blind, tilt it horizontal by angling the slats fully open
2. Use your fingers to gently pull apart the lift cords where they’ve crossed or wrapped around each other
3. For tight knots, use a safety pin or needle to loosen the cord rather than pulling hard
4. Work from the knot outward, not from the ends toward the knot
5. If the cord has wrapped around a slat, slide it out rather than pulling it over the slat edge

Don’t cut the cord unless it’s broken. A trimmed cord that’s too short is no longer fixable.

Step 3: Re-Thread the Cord if It’s Come Out of a Slat

If the lift cord has slipped out of one or more slats, it needs to go back through in the right order. The cord runs through a hole in each slat from top to bottom, then loops back up through the ladder tape.

1. Hold one slat at a time and locate the small hole near the centre-left or centre-right (depending on which cord you’re working with)
2. Thread the cord back through the hole using your fingers or a piece of stiff wire as a guide
3. Check that the cord sits inside the ladder tape loop on each slat, not outside it
4. Work down slat by slat until you reach the bottom rail
5. Re-thread through the bottom rail hole and re-tie the original knot if it came undone (a simple overhand knot works fine)

Once re-threaded, the cord should run freely when you pull it.

Step 4: Test the Mechanism and Reattach to the Cleat

Before you declare it fixed, test it properly.

1. Pull the lift cord slowly to raise the blind partway and watch each slat to check they’re rising evenly
2. Lower it back down fully and check the cord runs smoothly through the headrail pulley
3. Raise the blind fully and listen for any catching or grinding in the headrail
4. Loop the cord around the cleat or engage the cord lock in the headrail to secure it at your preferred height
5. If the blind rises unevenly (one side higher than the other), the cords on each side may be different lengths. Feed a little slack from the longer side through the bottom rail hole and re-tie

If the cord is frayed but still intact, this is the point to decide whether to replace it before it snaps mid-use.