Both are aluminum plates, shedding tears for three months and not maintained for 34 years. Why?

Views:90 Author:Site Editor Publish Time:2026-08-17 14:22:01 Orgin:Site

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In the third month of delivery, the customer stood at the bottom of the building and pointed to the facade, asking:

Customer: This wall has only been installed for three months, why is it dripping down one by one?

Project Manager: That's gray, just rinse it off.

Rushed. Two months later, one after another, deeper than last time.

This thing has a particularly indecent nickname in the curtain wall industry, called 'pee wall print'. The scientific name sounds better, it's called vertical flow pollution.

Another building that was topped out in the same year had nothing done on its facade, not even signing a cleaning contract. From a distance, it still looked like it had just been delivered.

The difference is not in the construction team, nor in the diligence of the property management.

The difference lies in whether that layer of 'skin' is sprayed on or grown out.

1、One is wearing a piece of clothing, and the other has grown a shell

The method of making fluorocarbon aluminum plate is essentially two words: spray painting.

Fluororesin modified coating, sprayed on the surface of aluminum plate to form a paint film. To put it simply, it is a layer of polymer coating that becomes straight and white, and a layer of plastic.

The method of anodizing aluminum plates is completely different: electrolysis.

Throw the aluminum plate into the electrolyte (sulfuric acid, chromic acid, oxalic acid, etc.) as an anode, apply electricity, and a dense layer of aluminum oxide film (Al2O3) will grow on the surface of the aluminum. The conventional film thickness is 5-20 microns, and hard anodizing can achieve 60-200 microns.

These two sentences may seem similar, but they are actually one species apart.

One is pasted on, which is a "two-layer thing" with an interface in between, and the interface is the weak point;

One is grown and metallurgically bonded to the substrate. If you want to separate it from aluminum, you must first destroy the aluminum.

Clothes will tear, but the skin won't peel off.

All the performance differences behind are rooted in this sentence.

2、The hardness column is a bit absurdly poor

There is a common method for measuring surface hardness in the industry, the pencil hardness method, which involves drawing pencils of different hardness upwards.

·Paint film of painted board: between 1H and 3H, depending on the quality.

·Anodic oxide film: Use the hardest 9H pencil in the laboratory to scratch, it won't hurt.

That is to say, the hardness of the oxide film is greater than 9H - where is the upper limit? This method cannot determine it because there is no harder pencil available.

Let's change to a more familiar ruler. Mohs hardness: Diamond is on the 10th grade, Al2O。 Tied with Sapphire for level 9.

So the phrase 'Rolls Royce in the aluminum plate industry', although a bit of manufacturer promotion, is not empty in terms of hardness.

Take the hardest pencil and scratch on it, it's like tickling.

Where is this most deadly thing? A place within reach of human hands.

The subway station hall, airport check-in island, first floor of shopping malls, and exhibition halls are all touched by thousands of hands every day. After two or three years, the painted boards are covered in messy marks and scratches that cannot be wiped off. The thinner the paint film, the more it is wiped off.

3、"What really widens the gap is' dirty '

This is the most easily overlooked, but it determines what your building will look like in five years.

Looking at the two types of boards under a microscope, the image is quite frightening:

·Fluorocarbon paint film magnified 500 times: like a porous sponge, full of holes.

·Anodized film magnified 500 times: nothing can be seen, it's too dense. It had to be magnified 150000 times before the structure could be barely seen - like a tightly fitted wall.

Structure determines destiny.

Fluorocarbon paint film is a polymer resin that carries an electric charge and naturally absorbs dust. Ash is sucked up and drilled into the interior of the paint film through the pores. When it rains, water carries dust and drips down, creating an indelible "urine wall mark". Worse still, the paint film will gradually fuzz under ultraviolet light, becoming more and more absorbent, creating a vicious cycle.

Many fluorocarbon curtain walls begin to experience infiltration and vertical flow pollution after about three months of installation, and can only be cleaned frequently in the later stages.

Anodic oxide film is electrically neutral - with a surface tension of ≤ 30mN/m, it does not carry any charge and cannot firmly absorb dust, so it can only float on the surface. A rain washed it away.

This is not a "bonus point" in some projects, but an admission condition: semiconductor workshops, clean rooms, hospital operating areas, laboratories, and zero tolerance for dust accumulation.

There has been a lesson in the industry: in the workshop and corridor of a semiconductor factory, "imitation oxidation" boards were initially used to control costs, resulting in fading and surface dust, and later maintenance costs continued to rise. In the end, they were replaced with real oxidation boards.

The money saved will never disappear, it will only change its name and be called 'maintenance premium'.

4、The time column is the most indicative of the problem

The quality of the materials cannot be seen in three years, but it is clear in ten years.

There are too many scripts in the fluorocarbon industry: the inner layer of the paint film is prone to filamentous corrosion, followed by bubbling, peeling, and cracking; After weathering, the surface of the paint film becomes powdery, and the glossiness and color decrease together. Three to five years is a hurdle, and once the hurdle passes, the facade begins to show signs of aging. Anodizing has a nearly 70 year history of application abroad, and the sample size is large enough.

There are two cases worth considering:

·PPG, a leading global coatings company, has its own administrative headquarters and research and development center. The curtain wall is made of anodized aluminum plate and has been built for 34 years without any routine maintenance.

·The PONT DESEVRES office project in France, with an anodized aluminum curtain wall built for 46 years, also has no regular maintenance records.

A giant in the paint industry did not use their own paint on their storefront.

This is not black who. Fluorocarbon is still the absolute mainstay in the battlefield of paint with complex shapes, tricky colors, and budget constraints.

The choice of 'what to use for your own storefront' is itself a non advertising manual.

5、Why is there still fluorocarbon on the streets? Because we need to settle accounts

After discussing the advantages for a long time, it's time to talk about money.

The approximate range compiled through public channels (with significant differences in quality across different regions, for reference only)

The price is an estimated range compiled through public channels, subject to actual inquiries.

It's two or three times more expensive, that's for sure. The project budget is so large, and everyone understands what the first reaction of Party A is when they see this number.

But the account cannot only count this one amount.

A building that has been standing for 20 years, fluorocarbon needs to add: high-frequency cleaning fee+possible renovation or replacement after more than ten years; Anodizing is basically maintenance free.

Some customers understand it, while others do not - the difference is usually that they do not intend to own the building.

Self owned properties tend to be more prone to anodizing as they are calculated; I left after development, so the accounts are naturally not calculated this way.

I won't judge this, it's just a reality.

6、What projects should be included and what projects should not be forcefully included (recommended for collection)

This table is compiled based on my experience with the projects at hand, and can be used as a quick reference for selection:

One sentence principle: places that can be touched by hand, places that can be exposed to rain, and places that will be seen in twenty years are worth anodizing; Don't force yourself on parameters in other places.

7、You've probably seen these buildings before

List a few projects that use anodized aluminum plates. Next time you pass by, you can pay attention to the facades:

·The entire exterior of the Shanghai Planetarium features diamond shaped cutting panels at different angles, with each angle being different under sunlight and night lighting.

·Qingdao TAG · Xihai Art Museum - a work by Jean Nouvel, featuring 127 pieces of 1mx5m anodized electric sunshade fans hanging outside the "Hundred meter Corridor", with horizontal error controlled in millimeters.

·Suzhou Bay Cultural Center - The "∞" shaped large ribbon is made of anodized aluminum plate on the surface, reflecting the lake and mountain scenery, and can pull out a rainbow effect of over 500 meters.

·Hangzhou Tianmuli - Renzo Piano's first project in China, with a curtain wall of about 80000 meters, imported sheet anodized aluminum plate+surface molding process.

·The facade of the Yangtze River International Convention Center in Nanjing, facing the river, is composed of over 90000 specially made anodized aluminum plates and glass.

·Jiaxing Station - Ma Yansong is the "train station in the forest", and the ceiling of the waiting hall is made of anodized aluminum honeycomb composite panels.

It looks quite beautiful. But beauty is the result, not the cause,

The reason is that the film grew out of the aluminum and I have no intention of leaving.

8、Speak more truthfully

Good materials don't mean the batch you bought is good.

Also known as "anodizing", there are actually many pits:

·The difference in film thickness is half -3 microns is sufficient for indoor use, but not more than 10 microns for outdoor use. The answer will be seen in two years;

·Using the wrong materials for the substrate - ensuring oxidation (AQ) of hot-rolled cold-rolled aluminum and cheap cast rolled aluminum, completely oxidizing two things;

·Using "imitation anodizing" as anodizing for delivery - the appearance is almost imperceptible at the beginning, and it takes three years to reveal its original form;

·How to judge the quality of the oxide layer? There is a hard indicator in the EU standard, with a maximum weight loss value of 30mg/dm2, which can be rejected with one vote.

The good news is that these things can be tested on site and cannot be fake.

Eddy current thickness gauge, gloss meter, and spectrophotometer are one or three things, and the results will be available in a few minutes.

In conclusion

There is a saying in the curtain wall industry that I have always believed in: materials don't deceive people, sometimes people do.

Anodized aluminum plates are expensive, and there are reasons why they are expensive; Fluorocarbon is cheap, and it has its reasons for being cheap.