I've been on both sides of the plastic sheet business. Before joining Westlake, I bought plastic material from a distributor who could not tell me what was actually in the roll—standard, off-spec, or a different polymer altogether. Since then I've spent five years at Westlake, working in quality and brand compliance and reviewing several hundred shipments a year before they go out the door. These are the questions that arrive in my inbox repeatedly, answered the way I'd answer over the phone.
- How do I verify genuine Westlake material and the Westlake logo?
- Can Westlake rigid PVC sheet be used in mold remediation?
- What is PET (polyethylene terephthalate)?
- What is rigid PVC sheet?
- What is PP plastic?
- Why is the color of my second order different from the first?
The last question is the one most buyers do not think to ask until after they've opened the second delivery. It is worth reading before you place any large order that includes printed branding.
How do I verify genuine Westlake material and the Westlake logo?
I would start with the three things our technical team checks when a customer sends photos. First, the label and interleaf. Most genuine Westlake sheet arrives with the Westlake logo printed on the product label; roll goods also carry the logo on the interleaf or edge tape. A logo on only the outer stretch wrap is not enough, because outer wrap can be replaced during distribution.
Second, ask for a certificate of analysis for the batch. The certificate should show measured thickness, density, tolerance results, and a batch code that traces back to the production line. Anyone can print a logo. A verifiable batch code is harder to invent.
Third, send us the batch code and a clear photo of the label. We keep production records, and our team can confirm whether the material was produced in our facility. If a supplier cannot locate batch information, that tells you something: in our experience, material sold without batch traceability is usually intentionally untraceable.
Can Westlake rigid PVC sheet be used in mold remediation?
Short answer: yes, for containment. Rigid PVC sheet is frequently used in mold remediation to build temporary walls, doorways and airlock chambers around the work area. Unlike porous panel products, rigid PVC has a non-porous surface that gives mold no nutrients and can be wiped clean with disinfectants.
I should add a limitation. A PVC panel does not kill mold, treat mold, or remove it. Contractors use it for the structure around the remediation task, not as the remediation itself. If you need a licensed company to remove mold from a building, that is a service we do not provide. The plastic sheet is just one material that a good remediation contractor may choose for containment.
What is PET (polyethylene terephthalate)?
PET is a polyester thermoplastic made from ethylene glycol and terephthalic acid. In sheet form, PET is best known for clarity, gloss and consistent thermoforming behavior. Common applications include clear clamshells, blister packs, display trays, printed packaging and graphic overlays where the product needs to be seen.
PET is also one of the more straightforward materials to recycle. Clean post-consumer PET can be reprocessed into rPET resin, and Westlake offers PET sheet with meaningful recycled content. That matters for brands trying to reduce virgin plastic use without sacrificing the way the material forms on a thermoforming line.
One quality point that buyers miss: PET is hygroscopic. It absorbs moisture from the air. If PET sheet is not properly dried before thermoforming, formed parts may show cloudy areas or a rough surface. When a customer tells me PET doesn't work, drying is the first thing I ask about.
What is rigid PVC sheet?
Rigid PVC sheet is unplasticized polyvinyl chloride—uPVC. Unplasticized means the compound has no plasticizer added to soften it. Flexible PVC films and sheets contain plasticizers; rigid PVC does not, so it remains stiff and dimensionally stable.
It is used in thermoformed trays, industrial components, printed graphics, point-of-sale displays and fabrication work. It also offers good chemical resistance and is naturally more flame-resistant than many hydrocarbon-only plastics.
The confusion I see most often at the quality stage is between rigid PVC sheet and PVC foam board. Foam board has an expanded cellular core: lighter, softer and popular for signs and displays. Solid rigid PVC sheet is denser, with a harder surface and cleaner cut edges. If you are fastening parts, thermoforming deeply, or need a smooth structural surface, solid sheet is usually the right call.
Also worth knowing: PVC on a spec sheet does not tell you everything. Compounds can include impact modifiers, lubricants, fillers or recycled content, and those change processing behavior. Ask for the specific gravity and compare the full datasheet, not just the product name.
What is PP plastic?
PP plastic is polypropylene, a lightweight thermoplastic polymer made from propylene monomers. It is known for chemical resistance, low moisture absorption and excellent fatigue resistance. That fatigue resistance is why flip-top closures and folding containers use living hinges—parts that can bend repeatedly without cracking.
Polypropylene has a different profile from PET and PVC. In sheet form, it is commonly found in chemical tanks, reusable totes and applications where weight savings matter. Polypropylene is naturally translucent, so if clarity is the goal, PET usually leads. It also has low surface energy, meaning inks and adhesives bond poorly unless the surface is treated.
From a quality standpoint, I would never choose a polymer by name alone. I ask what the part will touch, what temperature it will see, what visual standard it must meet, and how it will be printed or joined. PP is the best answer for some of those questions, and the wrong answer for others.
Why is the color of my second order different from the first?
This is the question I wish every customer asked before ordering, not after receiving. Plastic color varies from lot to lot because resin, heat history, recycled content and pigment dispersion all influence the final tint. Even the same recipe can produce a small shift when the extruder runs at a different speed or the factory temperature changes.
That is why color needs numbers. The Pantone Color Matching System guidelines define Delta E below 2 as acceptable for brand-critical colors; Delta E of 2 to 4 is noticeable to trained observers; above 4 is visible to most people. As of January 2025, our QC release criteria for brand-critical colors is a measured Delta E of 2 or below against the approved physical master sample. We check every order with a spectrophotometer, not only visually.
When we introduced recycled PET options in 2024, I spent weeks second-guessing the decision. The upside was giving customers recycled content; the risk was a slight warm cast in clear sheet. In the end, the instrumentation settled it: we adjusted the pigment formula and made sure every run passed the same Delta E gate. It is now routine, but it did not become routine by hope.
A practical tip: when you order, ask for color to be matched to the approved physical master sample, not to a PDF. And if your logo is part of the print job, supply a vector file or a high-resolution raster at 300 DPI at final print size. Low-resolution artwork is a color problem no material supplier can fix.