PDLC and PNLC can each be built Normally OFF (Frosted) or Normally ON (Clear). For Normally OFF (Frosted) glass, like a meeting room or a bathroom, PDLC is the better choice. For Normally ON (Clear) glass, like a shop window that must stay clear in a power cut, PNLC is the better choice.

What are PDLC and PNLC?

PDLC and PNLC are the two liquid crystal technologies behind privacy smart film. Both switch between clear and frosted with a click. PDLC (polymer dispersed liquid crystal) is the standard privacy film: frosted with the power OFF and clear with the power ON. PNLC smart film (polymer network liquid crystal) is best known as reverse film: clear with the power OFF and frosted with the power ON.

The real difference is not the name but the structure inside the film. That structure decides which switching mode each technology does best, how clear it looks and what it costs to make.

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How PDLC Works: Droplets in a Polymer

In PDLC film, tiny liquid crystal droplets are trapped inside a solid polymer. The polymer makes up a large share of the layer, often 30% to 50%. The layer sits between two thin PET films with a transparent conductive coating.

Each droplet takes its alignment from its own wall, so with the power OFF the droplets point in random directions. Light scatters and the film looks frosted. With the power ON, the electric field lines the liquid crystal up and the film turns clear. Our guide to PDLC smart film covers the layers in more detail.

How PNLC Smart Film Works: A Polymer Network

PNLC turns the recipe around. The liquid crystal is one continuous layer, often 80% or more of the mix, and a thin polymer network runs through it like a scaffold. There are no sealed droplets.

In reverse PNLC smart film, alignment layers on both films line up the liquid crystal with the power OFF, so light passes straight through and the film is clear. With the power ON, the molecules try to turn, but the polymer fibers hold back the ones near them. The layer breaks into many small zones that point in different directions, and the film turns frosted.

Normally OFF (Frosted) vs Normally ON (Clear)

Normally OFF (Frosted) means the film is frosted with no power and clear when switched ON. Normally ON (Clear) means the film is clear with no power and frosted when switched ON, which the market calls reverse film. Both technologies can be built both ways:

So PNLC is not automatically reverse, and PDLC is not automatically frosted. Each one simply has a mode it does best.

Why is Reverse Film Usually PNLC?

Reverse film must be clear with no power. For that, all the liquid crystal has to point the same way while the film rests, and its index has to match its surroundings.

• PDLC Struggles: The droplets are sealed inside the polymer. Alignment layers on the films only touch the liquid crystal at the surface, so they cannot reach droplets deep in the layer.

• PNLC Works: The liquid crystal is one continuous layer, so alignment layers can orient all of it. The small amount of monomer is cured while the liquid crystal is already aligned, and the network locks that alignment in.

In short: in PDLC the polymer isolates the liquid crystal, while in PNLC it stabilizes a layer that is already aligned. That is why almost every reverse film on the market is PNLC.

Reverse PDLC and Normally OFF PNLC: What Happens?

Each technology can be pushed into its weaker mode. It works, but the result explains why the market settled where it did.

• Reverse PDLC: Makers use a special liquid crystal and treat the polymer surface so the droplets line up at rest. The clear state is usually hazier than reverse PNLC, especially when you look at an angle, and the film is harder to make the same from batch to batch. That is why it is rare.

• Normally OFF PNLC: This works well, and it can switch at a lower voltage than PDLC. But you pay the higher PNLC material cost for a result that standard PDLC already gives. Few projects need that trade, so few suppliers offer it.

Why is PNLC More Expensive?

Reverse PNLC costs several times more than standard PDLC. The price gap comes from the materials and from extra steps in production:

Liquid crystal is usually the most expensive ingredient in the film, and PNLC uses much more of it. Add the coating step, the tighter process and the smaller market, and the price difference follows. For a full price picture, see smart glass vs smart film cost.

Which One Should You Choose?

Start with one question: what should the glass look like when nobody touches the switch?

• Choose PDLC: glass that should be private most of the time: meeting rooms, bathrooms, clinic rooms and partitions. It is the lowest-cost route to privacy at a click.

• Choose PNLC: glass that should be clear most of the time and private now and then, or that must stay clear if the power fails: shop windows, lobbies and retail fronts.

• Same Formats: Both come as adhesive smart film for existing glass in dry areas and as laminated smart film for glass laminators.

Know the limits too. PDLC needs power to stay clear and turns frosted in a power cut. Neither film is a heat blocker, so for heat control pair it with a solar film. Our guide to smart glass technologies compares PDLC and PNLC with blackout, SPD and electrochromic glass, and what is smart glass covers the basics.

Ready to choose? Office and home owners: send us your glass sizes and get a quote. We will reply with a dedicated plan. Film installers: become an SFI installer and add smart film to your services.

FAQ

Is PNLC Always Reverse Film?

No. PNLC can be built frosted or clear with the power OFF. Most PNLC on the market is reverse film because that is the mode it does best.

Is PDLC Frosted When OFF?

Standard PDLC is frosted with the power OFF and clear with the power ON. Reverse PDLC exists, but it is rare.

Why Does PNLC Cost More?

It uses more liquid crystal, a special grade of it, extra alignment coatings and a tighter production process, in smaller batches.

Can PNLC Film Be Laminated?

Yes. PNLC comes in a lamination type as well as an adhesive type, so glass laminators can build reverse smart glass.

Can I Add PNLC Film to Existing Glass?

Yes, with adhesive PNLC film on existing glass in dry areas. Wet areas need laminated glass.

Does Either Film Block Heat?

No. PDLC and PNLC are privacy products, not heat blockers. Both block up to 99% of UV.