About the Lumitester ATP Test

During test installations and demo applications, we sometimes use Kikkoman's testing device, the Lumitester, to quantify the level of residue on a treated surface. However, this number does not simply prove the effectiveness of photocatalytic action by itself. Because the device is highly sensitive, readings can be strongly affected by the conditions at the time of measurement. In this article, we've put together a guide to reading these numbers correctly.

How to Read Your Lumitester (ATP) Results

What NanoZone Coat's Photocatalytic Protection Does — and Doesn't Do

This article explains how to read ATP (Lumitester) results and what NanoZone Coat's photocatalytic protection actually does, based on one-week inspection data from an actual installation. Our goal is not to present the numbers in the most flattering light. For that reason, we have kept two measurements that still call for continued attention in the data shown below, rather than leaving them out.

1. What the Lumitester Actually Measures

The Lumitester is a device that measures ATP, ADP and AMP — substances found in organic residue such as sweat, skin oils and food debris. It does not count living microorganisms directly. It is best understood as a cleanliness indicator, widely used in hospitals and food facilities to check how thoroughly a surface has been cleaned.

It is just as important to understand what the Lumitester does not measure. It does not directly measure photocatalytic activity itself. It is simply one useful indicator of surface cleanliness, and that is the purpose for which we use it — a way to track how clean a surface stays over time, rather than a direct measurement of the coating's own performance.

2. Why a Single Reading Can Vary

A Lumitester reading is a snapshot of one moment, at one point. The result depends on who touched that spot just before testing, what had been placed there, exactly where the swab was taken, and whether that surface had recently been exposed to light.

This is simply a feature of how the test works on any surface, coated or not — it is not a sign that something is wrong. That is why we always recommend evaluating the same point across several inspections and looking at the trend, rather than drawing conclusions from any single reading.

3. Why Good Protection Doesn't Always Mean an Immediate Drop in Numbers

Why can a reading stay elevated for a while even on a surface that is genuinely being protected? That's a fair question, and the honest answer involves three points about how ATP testing and photocatalytic reactions each work.

3.1 Scale

How much a photocatalytic reaction can break down depends on the amount of light available and the surface area of the catalyst (titanium dioxide). By contrast, the amount of oil and residue left behind by a single touch is far greater than the amount of microorganisms present. Because there is simply more material to break down, fully decomposing a heavy residue load can take longer than one might expect.

3.2 Neutralizing Is Not the Same as Fully Breaking Down

Microorganisms are relatively quickly neutralized once their outer membrane or proteins are damaged — this happens fairly fast under photocatalytic action. The complete breakdown of the organic material itself, which is what lowers the ATP reading, is a separate and slower chemical process. The two run on different timelines.

3.3 The Lumitester Cannot Tell Inactivated Residue from Active Residue

This is the most important point. Even after a microorganism has been neutralized, its remains still contain ATP and AMP. The Lumitester cannot distinguish between organic matter that is still active and matter that has already been rendered harmless. In practice, this means a surface can read as elevated for a period of time even while it is being continuously protected.

In short: a single elevated reading does not mean NanoZone Coat isn't working. What matters is whether readings at the same point trend downward over repeated inspections and stay low. That is exactly what we track over time.

4. How NanoZone Coat's Photocatalytic Protection Works

NanoZone Coat works through microscopic titanium dioxide (TiO₂) particles bonded to the treated surface. It does not form a continuous film or sealant layer the way a varnish or sealant does. The particles remain on the surface, and when exposed to light they continuously break down organic matter and help neutralize microorganisms on contact. This is not a one-time cleaning action — it is an ongoing background process.

A Note on “Residue Rising to the Surface”

You may come across this phrase when unexpected readings are being explained. To be precise, it does not mean old residue is being physically pushed up through the coating. Because NanoZone Coat does not form a sealed film, if organic buildup was already present before treatment, the layer closest to the titanium dioxide particles may begin to break down and change first. As a result, residue that had been further underneath can end up being the material a swab happens to pick up. This is a known, explainable effect, not a defect. It is also why we recommend removing visible heavy soiling before treatment wherever possible.

NanoZone Coat is a complement to regular cleaning, not a replacement for it. Cleaning physically removes dirt and debris; NanoZone Coat works continuously between cleanings to help a surface that has already been cleaned stay that way for longer.

5. What This Looks Like in Practice — A Real-World Example

Building on the explanation above, here is a sample of actual measurement data from a real installation, shared so the way these numbers should be read can be seen concretely. This is only one example, and it is not meant to suggest every installation will produce the same results. Readings are given in RLU (Relative Light Units), where lower numbers indicate a cleaner surface. As a general guideline, a common pass threshold is under 2,000 RLU for lower-touch points such as guest-room surfaces, and under 5,000 RLU for higher-traffic points such as shared restrooms.

Guest Room Points (5 points)

Even at frequently touched points such as the door knob and TV remote, readings dropped sharply right after treatment and remained low a week later.

Kitchen Equipment (6 points)

* On a couple of items, the one-week reading came in slightly above threshold, or came down into range on a retest taken after brief light exposure.

As this example shows, points where complex shapes, frequent direct food contact, and limited light exposure during storage overlap — as is common with kitchen utensils — can show a slower decline in readings, or a temporarily elevated result, compared with other points. This is one example of exactly the lag between neutralization and ATP residue described in Section 3.

Shared Restroom Points (6 points)

A striking feature of this example is that the points with the highest pre-treatment readings (20,454 / 13,767 RLU) had fallen to a small fraction of their starting values a week later. This illustrates that the points which ran highest under routine cleaning alone tend to show the largest before-and-after change.

6. In Summary — Key Points for Reading ATP Results

ATP (Lumitester) readings are a useful and widely used indicator in hygiene management, but reading them accurately takes a few things into account. For anyone who may see ATP results in the future, here are the key points worth keeping in mind.

•   ATP testing measures surface cleanliness. It does not directly measure disinfection, sanitization, or the action of a specific technology such as a photocatalytic coating. It is best treated as one useful indicator among several, not the whole picture.

•   A single reading is only a snapshot of one moment at one point — it varies with who touched the spot, what had been placed there, and exactly where the swab was taken. Rather than reacting to any one number, it's more meaningful to track the same point across repeated measurements and look at the trend.

•   Even when an antimicrobial or antiviral technology such as a photocatalytic coating is actively working, neutralizing a microorganism and fully breaking down the organic matter that drives an ATP reading are two separate processes that run on different timelines. That's why a reading can stay elevated for a period of time even while genuine protection is at work.

•   Items with complex shapes and frequent direct food contact, such as tongs or spoons, tend to show readings that decline more slowly and vary more than flatter surfaces. It helps to read the numbers with the characteristics of the specific point in mind.

•   An antimicrobial coating is a complement to routine cleaning, not a replacement for it. Cleaning physically removes dirt and debris; the coating's role is to help a surface that has already been cleaned stay that way for longer between cleanings.

ATP readings aren't a simple pass/fail signal of “high means dangerous, low means safe” — they are an indicator that shifts with testing conditions and the characteristics of each point. Understanding not just the good numbers, but also why variation can occur, is the first step toward evaluating a hygiene program accurately as a whole.

This article is based on inspection data from an actual installation. The figures shown are real measurements; facility-identifying details have been omitted.