How to Protect Vertical Blinds from Sun Fading

Sun fading in vertical blinds happens because UV radiation breaks down the dye molecules in the fabric or PVC over time.

South and west-facing rooms get the worst of it, and most standard louvres aren’t made with prolonged direct exposure in mind.

You can slow the process significantly, and when fading does occur, you don’t have to replace the whole blind.

What You’ll Need

Tools

• Squeegee or credit card (for applying window film)
• Soft damp cloth
• Mild detergent

Materials / Replacement Parts

• UV-blocking window film (70%+ UV rejection rating recommended)
• Replacement louvres in a UV-resistant fabric or PVC
• UV fabric protector spray (optional, for fabric louvres)
• Louvre carriers or hooks if replacements don’t come pre-punched

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How to Fix It: Step-by-Step

Step 1: Reduce UV at the Source

The most effective thing you can do is stop UV light reaching the blind in the first place. A window film applied directly to the glass can block up to 99% of UV radiation while still letting light through.

1. Buy a film rated specifically for UV rejection, not just heat reduction. The two aren’t the same thing.
2. Clean the glass thoroughly before application. Any dust or grease will cause bubbling.
3. Apply with a squeegee or old loyalty card, working from the centre outward.
4. Leave 24-48 hours before touching the window again.

Step 2: Adjust How You Use the Blinds

Leaving louvres fully open and flat during peak sun hours (roughly 10am to 3pm in the UK) causes more fading than any other habit. A simple angle change makes a real difference.

1. Rotate the louvres to a 45-degree angle rather than leaving them parallel to the window.
2. During very bright spells, close them fully or tilt them so direct light bounces off rather than passing straight through.
3. If the room allows it, draw a secondary curtain across during peak hours and open the blinds once the direct sun has shifted.

Step 3: Treat the Fabric

If your louvres are fabric rather than PVC, a UV protector spray adds a layer of resistance to the fibres themselves. It won’t reverse existing fading but it slows future damage.

1. Take the louvres down before spraying. Don’t apply while they’re hanging.
2. Lay them flat and apply an even coat from about 30cm away.
3. Leave to dry fully (check the product instructions, but most need two to four hours).
4. Reattach and repeat once or twice a year.

Step 4: Replace Faded Louvres

Once louvres are faded, there’s no treatment that brings the colour back. The good news is that louvres are sold individually or in small sets, so you don’t have to buy a full replacement blind.

1. Match the colour and width of your existing louvres before ordering. Take one down and measure the width carefully, as 89mm and 127mm are both common but not interchangeable.
2. When choosing replacements, look for louvres described as UV-resistant or fade-resistant. Acrylic-coated PVC louvres generally outperform plain PVC in direct sun.
3. Check whether replacements come pre-punched. If not, you’ll need to match the existing hole position exactly before hanging.
4. Once fitted, apply window film to the glass if you haven’t already. Otherwise the new louvres will fade at the same rate as the old ones.