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Somewhere in my second year of building keyboards, I bought a 120-pack of switch films because a video told me every switch “needs” them. I filmed an entire board’s worth of premium switches that already felt fantastic, and I genuinely could not tell the difference in a blind test against my own unfilmed board. That taught me the single most important thing about switch films: they are a fix for a specific problem, not a universal upgrade.
This guide explains exactly what switch films do, how to tell if your switches actually need them, which material to buy, and how to install them properly, so you don’t waste money on films your switches don’t need.
⚡ Quick Answer
Switch films are thin pieces of plastic, usually polycarbonate (PC) or PET, installed between a switch’s top and bottom housing to fill manufacturing gaps. They reduce housing wobble and tighten the sound profile. You don’t need them on every switch. They help most on switches with looser tolerances (budget switches, older or worn switches) and provide minimal benefit on already-tight premium switches. Test for wobble first before buying films for an entire board.
1. What Are Switch Films, Exactly?
A switch film is a thin, precisely cut piece of plastic, most commonly polycarbonate (PC) or PET (occasionally PORON foam), shaped to fit the rim where a switch’s top housing meets its bottom housing. During manufacturing, these two halves are produced to a tolerance, and that tolerance leaves a microscopic gap. The film fills that gap.
🎯 What It Fixes
Housing wobble: the small lateral or rotational movement of the top housing relative to the bottom housing during a keystroke.
🔊 Side Effect
A tighter housing fit changes the acoustic resonance of the switch, typically producing a deeper, more controlled sound, what the community calls “thock.”
2. Why Housing Wobble Happens
Every switch housing is injection-molded, and even tight tolerances leave a small gap between the top and bottom pieces. This gap allows slight lateral and rotational movement during a keystroke, what enthusiasts call “wobble.” Older switches, worn switches, and budget switches tend to show more wobble because of looser tolerances or material wear over time.
Wobble is rarely large enough to see, usually well under half a millimeter, but it is very audible. It manifests as a hollow, inconsistent “clack” rather than a clean, controlled sound, and it can make a keyboard feel less premium even when the switches are otherwise good quality.
3. Do You Actually Need Films?
🧪 The Wobble Test (do this first). Hold a single switch and gently try to rock the top housing side to side relative to the bottom. If you feel noticeable movement or hear a faint rattle, your switches will likely benefit from films. If the housing feels solid with essentially no perceptible movement, films will provide minimal improvement, so save your money.
| Switch Profile | Films Likely To Help? | Why |
|---|---|---|
| Budget switches (Outemu, basic Akko) | ✅ Yes | Looser factory tolerances are common |
| Older or heavily-used switches | ✅ Yes | Plastic wear increases the housing gap over time |
| Known “loose batch” switch models | ✅ Yes | Community-documented tolerance issues |
| Premium switches (Gateron Ink, Oil Kings) | ⚠️ Maybe | Tighter tolerances, test before buying |
| New switches with tight factory fit | ❌ Unlikely | Already minimal gap to fill |
| Pre-filmed switches from manufacturer | ❌ No | Already addressed at the factory |
📌 Test before you commit. Film 5–10 switches first and compare them against unfilmed switches in a side-by-side type test. If you can’t tell the difference, you’ve saved yourself the time and cost of filming an entire keyboard’s worth of switches.
4. Film Materials: PC vs PET vs PORON
Polycarbonate (PC) films are the most rigid and produce the tightest housing fit, maximising the deep “thock.” PET films are slightly less rigid, offering a more moderate tightening effect. PORON foam films are soft and compressible, used less often, mainly on very loose or worn switches where a harder film might not seat well.
| Material | Rigidity | Sound Impact | Best For |
|---|---|---|---|
| Polycarbonate (PC) | High | Maximises thock depth | Enthusiasts wanting max sound impact |
| PET | Medium | Subtle, balanced tightening | General improvement, budget option |
| PORON foam | Low (compressible) | Dampens, slightly muffles | Very loose or old switches, quiet builds |
5. Choosing the Right Thickness
Most switch films are sold in 0.125mm and 0.15mm thicknesses, with some 0.2mm options for switches with larger housing gaps. The general guidance:
- 0.125mm: a safer, more conservative starting point, particularly for switches you suspect already have tighter tolerances.
- 0.15mm: the most common recommendation, providing noticeable wobble reduction for the majority of switches.
- 0.2mm: reserved for unusually loose housings; can occasionally cause reassembly difficulty if the gap is smaller than expected.
⚠️ Too thick can cause problems. If a film is thicker than the actual housing gap, the top housing sits slightly raised, making the switch harder to snap together or adding a slight increase in actuation force. If you feel resistance during reassembly, try a thinner film.
6. How to Install Switch Films
- Open the switch with a switch opener, separating the top housing from the bottom. Set the stem and spring aside.
- Position the film over the bottom housing rim. Most films have cutouts that align with the internal posts and the gold contact leaf, so do not cover the leaf.
- Check alignment. The film should sit flush with no overhang or wrinkling. Use tweezers for fine adjustment.
- Reassemble. Return the spring and stem, then snap the top housing back on. If it needs excessive force, the film may be too thick.
- Test. Press the switch and listen. A properly filmed switch should sound and feel noticeably tighter than before.
💡 Film before you lube. Handle the dry housing and film first, then apply lubricant to the stem and rails after the film is seated. See our switch lubing guide for the full process to pair with filming.
7. Common Misconceptions
🚫 “All switches need films.” False. Many modern premium switches already have tight tolerances and show minimal improvement. Test before committing to a full board.
🚫 “Thicker films are always better.” False. A film thicker than the actual gap can cause reassembly issues or a slight increase in actuation force. Start with 0.15mm unless you have a specific reason to go thicker.
⚠️ “Films will fix a scratchy switch.” Films address housing wobble, not internal friction. Scratchiness is a lubrication issue. Films and lube solve different problems and work best together, not as substitutes.
8. Frequently Asked Questions
What are switch films?
Switch films are thin pieces of plastic, typically polycarbonate (PC) or PET, that fit between a switch’s top and bottom housing. They fill the microscopic manufacturing gap between the two halves, reducing wobble and tightening the switch’s sound.
Do all switches need films?
No. Switches with already-tight tolerances, including many modern premium switches, show minimal improvement from filming. Films help most on looser housings: budget switches, older or worn switches, and certain batches known for looser tolerances.
How do I know if my switches need films?
Hold a switch and gently rock the top housing side to side relative to the bottom. Noticeable movement or rattle means films will likely help. A solid feel with no perceptible movement means films will provide minimal improvement.
What is the difference between PC and PET switch films?
Polycarbonate (PC) is more rigid and provides the tightest housing fit, maximising the deep thock sound. PET is slightly less rigid, offering a more moderate tightening effect. PC is the popular choice for maximum sound impact; PET is a reasonable middle ground.
Do switch films affect tactile bump or click feel?
Properly installed films sit at the housing seam, not at the stem’s tactile legs or click mechanism, so they shouldn’t meaningfully affect bump or click feel. A film that is too thick can occasionally introduce slight stem binding, so stick to 0.15mm unless you have a specific reason to deviate.
How long does it take to film a keyboard’s worth of switches?
Filming a 60–80 key keyboard typically takes 1–2 hours depending on experience, similar to lubing. Many enthusiasts film and lube in the same session since both require the switch to be disassembled.
Can switch films damage my switches?
Films are generally safe when correctly sized and carefully installed. Risks are limited to using the wrong thickness or excessive force during reassembly. There is no permanent modification involved, you can remove the film at any time.