uPVC window frames are known for being low-maintenance and long-lasting, but that doesn’t mean they stay spotless forever.

Over time, I’ve noticed stains, yellowing, and grime creeping onto my own window frames, and it made me realise just how much they can dull the overall appearance of a home.

The good news? With the right approach, you can easily bring them back to looking nearly new.

Let me walk you through how to remove stains from uPVC window frames—step by step.

Why Do uPVC Window Frames Stain in the First Place?

What causes yellowing and marks on uPVC?

uPVC is durable, but it’s not immune to discolouration. In my experience, the main culprits are:

• Airborne pollutants
  
• Traffic fumes (especially if you live near a main road)
  
• Bird droppings and tree sap
  
• General dirt and dust that’s allowed to build up
  

Is it just dirt, or something more stubborn?

At first, I thought it was just surface dirt, but after trying a quick wipe-down, I realised the stains were embedded into the material. That’s when I knew I needed a more thorough window frame cleaning strategy.

How environmental factors affect the frame colour?

UK weather doesn’t help much either—rain, moss, mould, and high humidity can all contribute to the yellowing of uPVC frames, especially the white ones.

What Tools and Products Do I Need Before Cleaning?

Before diving in, I like to make sure I’ve got everything I need. Whether I’m doing a light clean or tackling heavy stains, these are my go-to items.

Safe household items I always start with

• Warm water
  
• Washing-up liquid
  
• White vinegar
  
• Baking soda
  
• Soft cloths or sponges
  

Professional-grade products I keep for tough stains

Sometimes household items just don’t cut it. In that case, I use:

• uPVC cleaner (available at most DIY stores)
  
• Non-abrasive cream cleaners
  
• Mould and mildew sprays (for bathroom and window use)
  

Cleaning tools that won’t damage uPVC surfaces

• Microfibre cloths
  
• Soft-bristled brush
  
• Old toothbrush (great for corners and hinges)
  

Essential Supplies Checklist

• Bucket of warm soapy water
  
• White vinegar
  
• Baking soda
  
• uPVC cleaner
  
• Soft cloths or sponge
  
• Toothbrush or soft brush
  
• Gloves (optional but handy)
  

How to Remove Stains from uPVC Window Frames? – General Dirt and Surface Grime Removal

Step-by-step cleaning method using mild soap and water

Here’s what I do for a regular clean:

1. Fill a bucket with warm water & add 4 to 5 drops of washing-up liquid.
   
2. Use a soft cloth to gently wipe the frame, starting from the top down.
   
3. Rinse with clean water & dry with a microfiber cloth.
   

Why I avoid harsh abrasives and wire brushes?

In the past, I made the mistake of scrubbing too hard with the wrong tools—and ended up scratching the surface. Always use non-abrasive materials to preserve the uPVC finish.

How Can I Remove Tough Stains and Yellowing?

Using baking soda and vinegar mix

When I spot yellow stains, I make a simple paste:

• Mix baking soda with a splash of white vinegar to form a thick paste.
  
• Apply it directly to the stain and let it sit for 10 minutes.
  
• Gently scrub with a cloth or soft brush and rinse thoroughly.
  

When I switch to a uPVC-specific cleaner?

If the vinegar paste doesn’t do the trick, I turn to a uPVC cleaner. I apply it using a cloth, rub gently in circular motions, and then wipe away with a damp cloth.

A trick I learned to restore whiteness naturally

Here’s a little hack I picked up: after cleaning, wipe the frames with a vinegar-dampened cloth and let them air dry. It gives a natural boost to the white uPVC discolouration.

What About Mould or Mildew on the Frames?

My personal method using diluted bleach

Mould tends to build up in the corners or on older frames. I use a 1:10 solution of bleach and water, carefully dabbing the affected areas, letting it sit for five minutes, then rinsing thoroughly.

Ventilation and prevention tips I always follow

To keep mould from coming back, I always:

• Keep windows slightly open when possible to reduce moisture.
  
• Wipe down condensation in the mornings.
  
• Clean frames monthly, especially in winter.
  

Natural vs Chemical Options Comparison

• Natural (Vinegar, Bicarb): Eco-friendly, safe, mild but slower
  
• Chemical (Bleach, uPVC Cleaner): Fast-acting, stronger, but harsher
  

Do DIY Methods Really Work Compared to Store-Bought Products?

What worked best for me?

Personally, I’ve found that DIY methods work great for regular upkeep. But for deep-set stains, especially on older uPVC, a store-bought uPVC cleaner often gets better results.

When I think it’s worth investing in commercial cleaners?

If your windows haven’t been cleaned in a long time, or the staining is years old, I definitely recommend investing in a specialised cleaner. It saves you time and elbow grease.

How Do I Prevent Stains from Coming Back?

My regular cleaning routine

Every 4–6 weeks, I:

• Wipe down the frames with warm soapy water
  
• Use a vinegar rinse every other clean
  
• Dry thoroughly to avoid watermarks
  

Protective treatments that actually help

Some uPVC cleaners leave behind a protective film—I’ve found this helps repel dirt and reduce discolouration.

Table: uPVC Frame Cleaning Options – Pros and Cons

Method	Best For	Cost	Effort Level	Long-Term Results
Soapy Water	Light dirt	Low	Easy	Temporary
Vinegar Mix	Organic stains	Very Low	Medium	Good
uPVC Cleaner	Tough stains	Medium	Medium	Excellent
Bleach Solution	Mould/mildew	Low	High	Long-lasting

Common Mistakes I’ve Made (So You Don’t Have To!)

• Scrubbing too hard and scratching the frame
  
• Using coloured cloths that leave dye behind
  
• Forgetting to test cleaning products on a small patch first
  

Final Thoughts – Bringing Back the Sparkle

Cleaning uPVC frames might not be glamorous, but it’s incredibly satisfying to see them go from dull and stained to bright and fresh again.

Whether you’re using household ingredients or a professional uPVC cleaner, the key is being gentle but consistent.

Now that you know my go-to methods on how to remove stains from upvc window frames, give them a try and bring back that sparkle!