Window frame
Three finishes that look similar from a ladder and behave nothing alike. One accepts a non-abrasive cream cleaner sparingly, and on another, marks from mistreatment may be permanent.
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What this is, what tends to go wrong with it, and what to do about it.
What tends to go wrong
The green film outdoors, and NOT the same organism as the mould indoors. Where it grows is the diagnosis: shade, overhanging trees, or paving that does not drain.
Why it is difficult: Moisture control and recurrence
A living growth, not a stain. Killing it and removing the staining are two separate jobs, and neither addresses the moisture that caused it.
Why it is difficult: Porous and non-porous surfaces, Moisture control and recurrence, Cleaning, sanitising and disinfecting, Organic load, Surface roughness
Mostly textile fibres and skin, held by static as much as by gravity — which is why a dry cloth on a plastic surface makes it worse.
Why it is difficult: Static and dust, Mechanical action and abrasion, Why different surfaces get different dirt, Surface roughness
Fats and oils, which water alone cannot lift. Removed by surfactants, by heat, by solvents, or by alkalis that convert the fat into soap.
Why it is difficult: Why oil resists water, Emulsification
- Water marksvia its material
What hard water leaves behind when it evaporates instead of being wiped away. A mineral film, not dirt, and the fix is at the drying stage.
Why it is difficult: Water hardness, Evaporative deposition
- Moss and lichenvia its material
Three different organisms treated as one green problem. Where they grow tells you more about the fix than any product does.
Why it is difficult: Moisture control and recurrence, Surface roughness
- Silicone residuevia its material
Left by most furniture polishes, invisible, and present even after a finish has been stripped to bare wood. It is discovered on the day somebody tries to refinish.
Why it is difficult: Water-repellent and water-attracting surfaces, Coating thickness
- Mould fungivia its material
The organisms behind the marking. Around 1.5 million species, each with its own conditions — and killing them does not end the exposure they created.
Why it is difficult: Organic load, Moisture control and recurrence, Biofilm
The science behind this: Corrosion and passivation, Alkali attack on light metals, Coating thickness, Solvents and polymers, Mechanical action and abrasion, Material compatibility
In detail
Window frames are uPVC, coated aluminium, anodised aluminium or painted timber, and the finish decides the method in every case. A uPVC manufacturer's care guidance is soapy water, with a domestic non-abrasive cream cleaner permitted for stains that will not shift, used sparingly because it can affect the gloss finish, and solvent-based cleaners prohibited outright. Coated and anodised aluminium are governed by a standards document whose escalation starts at water alone and stops at a mild detergent, with strong solvents, abrasives and aggressive acid or alkaline cleaners excluded; on anodised finishes it names trisodium phosphate, phosphoric acid, hydrochloric acid, hydrofluoric acid and fluorides specifically. Two instructions from the aluminium standard matter here. Do not clean a hot, sun-heated surface, because reactions accelerate unevenly and streak the finish. And identify the finish first, because marks from mistreating an anodic coating may be permanent.
Related
- Window frame is made from uPVC
- Window frame is made from Anodised aluminium
- Window frame is made from Powder-coated aluminium
- Window frame is made from Finished wood flooring
- Window frame is commonly affected by Algae
- Window frame is commonly affected by Mould
- Window frame is commonly affected by Dust
- Window frame is commonly affected by Grease
Sources for this page
Sources
PVC-U Window & Door Systems: Handling, Installation, Maintenance and Care Guide
The VEKA UK Group (VEKA and Halo profile systems), 2014 · Manufacturer documentation
Relied on for: That uPVC frames are cleaned with soapy water, that a non-abrasive cream cleaner may be used sparingly for stubborn stains because it can affect the gloss finish, and that solvent-based cleaners must never be used. (states this directly)
AAMA 609 & 610-02: Cleaning and Maintenance Guide for Architecturally Finished Aluminum
American Architectural Manufacturers Association (AAMA), 2002 · Standards body
Relied on for: That the escalation for finished aluminium is water then mild detergent, that strong solvents, abrasives and aggressive acid or alkaline cleaners are excluded, that named acids and fluorides must not be used on anodised surfaces, and that hot sun-heated surfaces must not be cleaned. (states this directly)