by Mr. Xiao

Senior Product & Applications Specialist · Feltcombo Material Suzhou Co., Ltd.
10 Years in PET Acoustic Materials · China & Thailand Dual-Factory Operations

Nine millimetres. It doesn't sound like much — barely thicker than a stack of eight credit cards. But in the world of PET acoustic panels, 9 mm is the specification that moves the most volume, wins the most projects, and generates the most questions from buyers who are serious about getting it right.

In ten years of working with these materials — across production lines in Jiangsu and Guangdong, and now our Thailand facility — I've answered the same three concerns from distributors, project procurement teams, and wholesale buyers more times than I can count:

• Is 9 mm actually dense enough, or am I compromising on acoustic performance?

• Can a 9 mm PET panel genuinely pass ASTM E84 Class A — and how do I verify it?

• If I'm sourcing from a Thailand factory rather than China, is the quality the same?

This article addresses all three, without the marketing gloss. If you're evaluating 9 mm PET acoustic panels for a real project or a distribution arrangement, the information here should give you what you need to make a decision you can defend.

Why 9mm Is the Industry Standard Thickness

The dominance of 9 mm in the PET acoustic panel market isn't a coincidence. It's the outcome of a decade-long market sorting process where contractors, designers, and distributors converged on a thickness that balances four things simultaneously: adequate acoustic performance, manageable weight per panel, clean CNC processability, and a per-unit cost that makes commercial rollouts viable.

Let me put some numbers behind that claim. A standard 9 mm panel at 1,220 × 2,440 mm weighs roughly 4.4–5.4 kg depending on density. That's light enough for a single installer to handle without mechanical assistance, and thin enough to sit within most wall finish build-up tolerances without requiring substrate modification. In a 10,000 m² office fitout — the kind of project that drives real volume — that weight difference per panel accumulates into significant installation labour savings.

From a specification standpoint, 9 mm sits in the sweet spot of the acoustic performance curve for mid-to-high frequency absorption — which covers speech intelligibility frequencies from 500 Hz to 4,000 Hz. This is the range that matters most in the environments where PET panels see the highest specification rates: open-plan offices, hotel lobbies and corridors, restaurant dining areas, and educational spaces. The very low frequencies — below 250 Hz — where 9 mm panels begin to lose absorption efficiency are rarely the primary acoustic concern in those applications anyway.

The practical consequence: 9 mm is the right answer for the majority of commercial acoustic projects. 12 mm steps things up for higher-performance requirements. 24 mm is for specialist applications. But 9 mm is where the market lives, and it's the reason we carry it in regular stock across 39 colours rather than treating it as a make-to-order item.

1500gsm vs. 1800gsm: Which Density Should You Choose?

This is the question that separates buyers who've done their homework from those who haven't. Thickness and density are two different variables, and you need to understand both to make a sound specification decision.

Density in PET acoustic panels is measured in grams per square metre (gsm) — essentially the mass of fibre compressed into each square metre of panel area. A higher gsm means more fibre per unit area, which translates to a denser panel. That density affects three things: acoustic performance, structural behaviour, and surface processability.

Acoustic Performance

The relationship between density and NRC (Noise Reduction Coefficient) in 9 mm PET panels is real but not linear. Here's what the test data shows for direct wall-mounted installation:

The Decision Rule

If you're specifying for a commercial project that requires ASTM E84 Class A or EN13501 Class B fire certification — and almost any meaningful commercial project in the US, EU, or UK does — then 1,800 gsm is your starting point, not 1,500 gsm. The higher density is what enables the fire-retardant chemistry to perform at Class A levels consistently across production batches.

Where does 1,500 gsm make sense? Two scenarios: Australian projects referencing AS ISO 9705 Group 1 (where we carry 1,500 gsm 9 mm certification specifically for this market), and projects where acoustic performance targets are modest and budget is the primary driver. In those situations, 1,500 gsm delivers real acoustic benefit at a lower cost point than 1,800 gsm.

What I'd caution against is treating the two as interchangeable. I've seen projects where a buyer specified "9 mm PET panels" without defining density, received 1,500 gsm material, and then couldn't meet the fire inspector's documentation requirement for Class A. The density spec is not a secondary detail — it's part of the specification.

Fire Certification Breakdown for 9mm Panels (EN13501 Class B, ASTM E84 Class A, AS ISO 9705 Group 1)

Let me be direct about something that causes confusion in the market: fire certifications are product-specific, not manufacturer-specific. A factory can hold an ASTM E84 Class A certificate for one product configuration and have no valid certification for a nominally similar product with different density or colour. This matters enormously when you're putting a specification on a project with real building inspector scrutiny.

Here is a precise breakdown of what each certification means and which Feltcombo 9 mm products carry which ratings.

ASTM E84 Class A — United States & Canada

ASTM E84, the Steiner Tunnel Test, evaluates the surface burning characteristics of interior finish materials by measuring two indices: Flame Spread Index (FSI) and Smoke Developed Index (SDI). Class A requires FSI ≤ 25 and SDI ≤ 450 — the highest performance tier under the standard. The International Building Code (IBC) references ASTM E84 for interior wall and ceiling finishes, which means it's the default compliance document for virtually every US commercial construction project.

For 9 mm PET panels, achieving Class A requires the fire-retardant treatment to be applied and integrated in a way that performs uniformly across the full surface — not just the test sample face. The test itself uses a 24" × 24' sample placed in the Steiner Tunnel for 10 minutes under controlled draught conditions. It's not easy to game; a poorly treated panel will fail, and the failure will be clearly documented in the test record.

Our 9 mm / 1,800 gsm panels carry ASTM E84 Class A certification. The original test certificate — including the accredited laboratory name, report number, and full test data — is available to any buyer as part of the standard documentation package. We don't summarise it on a data sheet and call it done; you get the primary document.

EN 13501-1 Class B — European Union & EU-aligned Markets

The European Euroclass system under EN 13501-1 is more comprehensive than ASTM E84 — it evaluates not just flame spread and smoke, but also flaming droplet behaviour (relevant for ceiling applications). The classification grades are A1, A2, B, C, D, E, F. For organic fibre-based materials like PET, Class B is the practical maximum achievable through fire-retardant treatment — and it's sufficient for the vast majority of European commercial interior applications including offices, hotels, retail, and education facilities.

Class B under EN 13501-1 does not mean inferior to Class A under ASTM E84. They're different test methodologies measuring overlapping but distinct fire behaviour characteristics. Our 9 mm / 1,800 gsm panels hold EN 13501-1 Class B certification. Holding both ASTM E84 Class A and EN 13501-1 Class B means the product is formally qualified for both US and European commercial project specifications — which matters significantly if you're a distributor operating across multiple markets.

AS ISO 9705 Group 1 — Australia & New Zealand

The AS ISO 9705 room corner test is among the most demanding fire test methodologies applied to interior finish materials globally. It's a full-scale burn conducted in an actual room-sized test enclosure, not a tunnel sample test — which is why Group 1 classification under this standard carries particular weight with Australian building certifiers. Our 9 mm / 1,500 gsm panels carry AS ISO 9705 Group 1 certification, making them compliant with the National Construction Code (NCC) requirements for specified occupancy classes in Australia and New Zealand.

One practical point worth making: ASTM E84 and EN 13501-1 are not interchangeable standards. A result under one system does not satisfy compliance requirements under the other. If you're distributing into both US and EU markets, you need both certificates — and the product that carries both needs to be the same SKU you're shipping. Confirm this explicitly before committing to an order.

Standard Size (1220×2440mm) — Why It Matters for Your Project

The 1,220 × 2,440 mm format — 4 feet × 8 feet in imperial — is not an arbitrary number. It's the dimensional standard that emerged from the global sheet goods industry and has been adopted as the construction industry baseline for panels, boards, and sheet materials across virtually every market. When a product ships in this size, it means everything downstream has been designed to work with it: the cutting waste calculations, the installation hardware, the freight stacking configurations, the warehouse racking systems.

For buyers, the practical implications are significant:

Coverage Efficiency

Each panel covers approximately 2.97 m². For a 500 m² wall project — a medium-sized open-plan office floor plate — that's roughly 169 panels. The waste factor at 1,220 × 2,440 mm is typically lower than at non-standard sizes because the dimensions align naturally with standard ceiling heights (2,400–2,700 mm in commercial construction). You cut less, you order less excess, and your cost-per-installed-metre is more predictable.

Freight Economics

Standard-sized panels palletise efficiently and stack consistently in 20-foot and 40-foot containers. Non-standard dimensions create awkward pallet configurations that either waste container space or require custom crating — both of which add cost. For distributors managing container economics, the 1,220 × 2,440 mm format is the one that pencils out correctly.

Installation Compatibility

The 1,220 mm width matches the standard stud spacing in North American and European framing systems (600 mm module × 2 = 1,200 mm face-to-face), which means the panel edges naturally align with vertical supports when direct-fix installation is used. This is not coincidence — it's why the format became a standard.

Color & Customization Options (39 Stock Colors + Custom Development)

One of the questions I get from new buyers is whether carrying 39 stock colours is genuinely useful, or whether it's just a catalogue number that looks impressive. I'll answer that honestly: 39 standard colours in regular inventory is a serious operational commitment, not a marketing claim. It means we're holding production runs across nearly 40 colour variants, managing fibre stock for each, and turning over inventory regularly enough that the panels you receive haven't been sitting in a warehouse for two years.

The colour range in the 9 mm line covers the spectrum that commercial and hospitality specifiers actually work with:

Neutral & Achromatic Range

White, off-white, light grey, mid-grey, charcoal, and black. These are the workhorses — the colours that move volume in corporate offices, retail fit-outs, and educational environments where the client wants acoustic performance without making a visual statement.

Warm Tones (2026 trending)

Terracotta, sand, warm beige, burnt orange, dusty rose. These have become increasingly active in hospitality and wellness-oriented commercial specifications. The wellness design and biophilic design trends that have been building since 2021 are now fully mainstream in commercial specifications, and warm earth tones are central to both aesthetics.

Cool & Nature-Derived Tones

Sage green, forest green, slate blue, dusty teal, stone. These align with the biophilic palette that interior designers are currently pulling toward — the idea that a workspace or hospitality environment should feel grounded and natural, not clinical and reflective.

Deep Accent Colours

Navy, deep burgundy, forest, near-black tones. Often used for feature wall applications, wayfinding panels, or as contrast elements in otherwise neutral environments.

Custom Colour Development

We follow colour trend forecasting actively — not because it's fashionable to say that, but because our supply chain partnerships mean we need to anticipate demand rather than react to it. If you have a project with a specific brand colour or a designer palette that falls outside our 39 stock options, custom colour development is feasible. The process involves matching against a provided reference (Pantone, NCS, RAL, or physical sample), a development period of 3–6 weeks for colour confirmation, and a minimum batch requirement for production. The exact minimum depends on the colour's position in our production schedule.

The practical advice: if you know you'll need a custom colour, contact us at the inquiry stage — not after the project programme has been locked down. Colour development lead time is the variable most likely to cause a delay, and it's entirely avoidable with early engagement.

China Factory vs. Thailand Factory — Same Quality Standards?

This is the question I've been asked most frequently since our Thailand facility began production in 2023, and I understand why buyers ask it. The concern is legitimate: manufacturing operations in a second country often means a second supply chain, different raw material sources, different production equipment, and potentially different quality outputs. In some industries and with some manufacturers, that concern is entirely justified.

Let me explain how we've approached this, because the answer isn't simply "yes, same quality" without some context for why that's true.

Identical Raw Material Specification

The PET fibre used in our Thailand production comes from the same supply chain and meets the same specification as our China factories — same polymer grade, same recycled content standard (GRS certified, ≥50% post-consumer), same fibre denier profile. The fire-retardant chemistry is applied using the same formulation and the same integration method. The starting material is not a different-quality, locally sourced substitute — it's the same raw material, shipped from the same supply chain.

Production Process Alignment

Our China production lines include four units specifically designed in Germany — the engineering specifications for those lines, in terms of pressing temperature profiles, density calibration, and surface finishing tolerances, are documented and repeatable. Our Thailand facility uses the same process parameters. This isn't something that happens automatically when you open a second factory; it requires deliberate process transfer, staff training, and validation runs. We did that before the Thailand facility shipped its first commercial order.

Quality Control Protocol

QC is where the quality consistency claim is either validated or falls apart. Our QC protocol in Thailand mirrors what we run in China — dimensional tolerance checks (±0.5 mm on thickness, ±2 mm on length/width), density verification per batch, fire-retardant treatment spot-checks, and colour consistency assessment against master standard panels. The same pass/fail criteria apply in both locations. Failed panels don't leave either facility.

Certifications: Same Product, Same Certificates

The ASTM E84 Class A and EN 13501-1 Class B certifications held for our 9 mm / 1,800 gsm panels apply to the product specification — not to a specific production facility. When we validated the Thailand production output against these certifications, we did it by running samples from the Thailand lines through the same testing methodology. The certification documentation available for Thailand-origin product is the same as for China-origin product.

Why We Have Thailand Production at All

The honest business reason for dual-country production is supply chain resilience — not because our China factories have a problem, but because five years of global disruption demonstrated that concentration of production in a single geography creates exposure for customers. A port disruption in southern China, a policy change affecting one province, a force majeure event — any of these can affect delivery timelines for customers who rely on a single-source supply chain.

The Thailand facility adds redundancy. If our China production has a scheduling constraint, Thailand can pick up the load. For North American buyers specifically, Thailand origin also provides options in the current tariff environment that a China-only supply chain cannot offer — which has become a meaningful factor in procurement decisions over the past two years.

Lead Times, MOQ & Ordering Guide

Procurement decisions don't live in isolation from project schedules, and project schedules are what actually drive order timing for most of our customers. Let me give you the practical supply information that determines whether a 9 mm PET acoustic panel order fits your timeline.

Stock Products — 9mm in 39 Colours

For standard 9 mm / 1,800 gsm panels in our 39 stock colours (1,220 × 2,440 mm, flame-retardant), inventory is maintained in our Jiangsu facility and replenished on a scheduled basis. For orders within our standard quantity ranges, dispatch typically happens within 5–10 business days of order confirmation and payment. Ocean freight to major European ports (Hamburg, Rotterdam, Felixstowe) runs 25–35 days; to US East Coast ports, approximately 28–38 days; to Australian ports, 18–28 days. These are approximate port-to-port times — your freight forwarder should be consulted for current vessel schedules and port congestion updates.

Custom Colours — Development Timeline

Custom colour development requires:

• Week 1–2: Reference receipt, lab colour matching, development sample production

• Week 3–4: Sample shipping to customer for approval

• Week 4–6: Colour approval and production scheduling confirmation

• Week 6–10: Production and QC

• Week 10–12: Dispatch

Plan for a total of 10–14 weeks from first contact to ex-factory for custom colour development orders. That's not unusually long for the category, but it does require planning. If your project programme doesn't allow for that lead time, the answer is to work from the closest stock colour, not to rush a colour development that then produces inconsistent results at production scale.

MOQ Guidance

Our MOQ structure is designed to accommodate both project procurement (where quantity is driven by coverage requirements) and distribution arrangements (where forward stocking is the purchasing model). Rather than publishing a single MOQ figure that doesn't account for the range of buying scenarios, I'd encourage buyers to contact us with their specific volume and product mix — we'll give a straightforward answer on whether it works and what the options are.

For distributors building an initial stock position, we can discuss forward-buy arrangements that allow you to establish inventory across a colour range without hitting the per-SKU minimums on every line item.

Application Gallery: Commercial Offices, Hotels, Schools

The most useful thing I can do here is describe how 9 mm panels are actually specified and installed in real project types — not with generic language, but with the detail that makes a procurement or specification decision more concrete.

Commercial Offices — Open-Plan & Mixed-Use

The typical commercial office application involves wall-mounted panels on one or more perimeter walls, often combined with ceiling baffles or ceiling clouds in the central open-plan zone. For a standard open-plan floor plate of 800–1,200 m², acoustic consultants typically target a reverberation time (RT60) of 0.4–0.6 seconds in the 500 Hz–2,000 Hz range — achievable with 25–35% acoustic surface coverage using 9 mm / 1,800 gsm panels.

In practice, this means treating major wall faces and specifying ceiling-level panels above desk clusters. The colourway choice in commercial offices has shifted noticeably in 2025–2026 toward warmer, more residential tones — charcoal grey, sage, off-white — reflecting the broader "hospitality-ification" of workplace design. The idea that a commercial office should feel cold and functional is largely gone from forward-thinking specifications.

Specification profile: 9 mm / 1,800 gsm / ASTM E84 Class A (North America) or EN 13501-1 Class B (Europe) / Standard 1,220 × 2,440 mm / Neutral or warm colourway from stock.

Hotels — Corridors, Public Areas & Guest Rooms

Hotel specifications are demanding in a specific way: the panel needs to look premium, survive cleaning cycles, pass fire inspection, and ship in quantities that accommodate multi-floor rollouts without colour batch drift. For hotel corridors — one of the higher acoustic treatment priority zones given the noise transmission from guest rooms and lift lobbies — 9 mm panels in a curated neutral palette are the standard specification.

Public areas (lobbies, restaurant dining rooms, bar areas) are where the design intent drives the specification more actively. These are the spaces where hospitality interior designers make active colour and finish choices, and where the 100+ colour range (across all panel thicknesses) becomes a real competitive advantage rather than just a catalogue claim.

Specification profile: 9 mm / 1,800 gsm / dual-certified (ASTM E84 Class A + EN 13501-1 Class B) / design-colourway from stock or custom development for signature spaces.

Schools & Educational Facilities

Educational facility specifications are driven by three requirements that often conflict: acoustic performance, safety profile, and budget. PET panels address the first two more comprehensively than any competing material — no irritant fibres, no VOCs, inherently mould-resistant, available in engaging colours that work in learning environments. The budget variable is where specifying from stock matters most: standard colourways at standard sizes avoid the cost premium of custom work.

In Australian educational projects, the AS ISO 9705 Group 1 certification on our 9 mm / 1,500 gsm product is specifically relevant — it's the certification that building certifiers in that market are most likely to require for educational occupancy classes.

Specification profile: 9 mm / choice of 1,500 gsm (AU) or 1,800 gsm (US/EU) / appropriate market certification / vibrant colourways from stock for primary; more restrained palette for secondary and tertiary.

Frequently Asked Questions