Internal reflective films have been used for decades to reduce heat and glare from inside the building. They work by reflecting solar energy back out through the glass, but they do so by reducing visible light and increasing reflectivity. This makes them effective, but not subtle.
Within this family, there are two very different groups:
Silver 20, 35 and 50 Interior Films are traditional, budget reflective films
3M All Seasons 35 sits in a completely different category from the Silver Reflective range. It is a superior technology that delivers better comfort, better light levels, and safer performance on modern glazing.
Allows significantly more natural daylight into the room than Silver 20 with equivalent heat rejection
Rejects more infrared heat, the part of sunlight responsible for overheating and discomfort
Reduces the radiator effect, where glass re‑radiates absorbed heat back into the room
Engineered specifically for modern double glazing, where standard Silver films can be risky
Performs exceptionally well in overhead glazing, roof lanterns, skylights, and atriums
Roof glazing where the external pane cannot be reached
Apartment windows and upper floors with no external access
Modern double glazing requiring a balanced internal solution
Areas where maintaining daylight is important
3M All Seasons 35 is the internal reflective film we recommend when an external installation is impossible and when comfort, daylight, and safety on modern double glazing matters.
The budget classics for internal solar control
Silver Reflective films are the original solar control window films. They are generally less expensive and deliver noticeable reductions in heat and glare, but they achieve this by being highly reflective and visibly tinted. They darken interiors, create internal reflections at night, and are visually obvious from outside.
The darkest and strongest of the range. It rejects a good amount of heat but creates a very mirrored appearance. Indoors, it produces the familiar “two views” effect. You can see outside, but you also see a reflection of your own interior.
A moderate option that balances light and heat more evenly, but still looks reflective and tinted. It is often chosen only when budget is the primary driver.
A lighter film that allows more daylight in, but its heat rejection is too weak to be considered effective on modern double glazing. It is rarely used today.
Can be used on double glazing as a budget-only option
Not suitable for triple glazing under any circumstances
Silver films remain in the portfolio because they are affordable, but they are no longer the best-performing solutions.
Reflective Interior Films Heritage
Reflective interior films were originally developed for single‑pane glass, where they delivered excellent heat and glare reduction at a low cost.
As glazing has evolved into double and triple units, their effectiveness has naturally declined, and the increased risk of thermal stress has made them less suitable. This shift created the need for more advanced innovations, such as 3M All Seasons, Reflective Exterior & 3M Prestige films.
High‑performance external films stop heat before it enters the glazing system dramatically increasing effectiveness on modern glazing systems.
They are solar control films applied to the inside surface of the glass. They work by reflecting solar energy back out through the glazing, reducing heat and glare inside the room.
Silver 20, 35 and 50 interior films are traditional, budget reflective films that rely on strong aluminium reflectivity and tint to reduce heat.
All Seasons 35 is a more advanced internal reflective film designed with alloys for modern double glazing, offering better daylight & better infrared rejection.
3M’s All Seasons innovation is more expensive than the Silver Reflective Interior films
Silver 20 is the darkest. 3M All Seasons lets in twice as much light as Silver 20 and still outperforms.
Silver 35 also lets in twice as much light but heat rejection is dramatically reduced.
Silver 50 is the lightest but rarely used on modern double glazing as its performance is not effective.
The film itself is rarely the weak point. Issues are usually caused by installation errors such as contamination under the film, edges cut too tight to the gaskets, or corners lifting over time.
When interior lights are on and it’s dark outside, the reflective layer behaves like a mirror.
For this reason Dual Reflective films have been designed to be reflective on the outside but dramatically reduced on the inside.
Silver films can be used on double glazing as a budget option, but they are not ideal for modern double glazed units. It is advised to check compatibility.
All Seasons 35 is specifically engineered for modern double glazing and is the safer, more balanced internal choice.
No. Internal reflective films should not be applied to triple glazing. External films are the only safe option.
Because external access can be impossible on conservatory roofs. Some roof lanterns & skylights also have an external self-cleaning coating which is not compatible with exterior films.
3M All Seasons 35 provides strong heat rejection while keeping the space bright.
Yes they block up to 99.9 per cent of UV, the main cause of fading.
Price. They remain the most affordable internal solar control films, even though more modern and subtle alternatives exist.
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