Checklist: Technical Specs to Request from Nonwoven Suppliers

What to include in a supplier inquiry

A standard product code or catalog description is rarely enough. When you send a supplier inquiry, you need to ask for data that proves the fabric behaves as expected in your specific application. The goal is to move from a conversation about general capabilities to a discussion about measurable performance.

Start by asking for the exact machine configuration used for the fabric. A supplier may list a product as “spunbond nonwoven” without specifying if it is produced on a single needle, double needle, or multi-needle line. These differences affect fiber orientation, puncture strength, and cost. If you are buying for filtration, ask about the meltblown content and the bond type used.

For instance, a single-needle line creates a fabric where fibers are randomly oriented across the width of the roll. A multi-needle line creates distinct lanes of fiber deposition. If your application requires uniform tension across the web, the lane structure of a multi-needle machine becomes a critical variable. You must specify the number of needles per row and the spacing between them. This level of detail helps you predict how the fabric will behave when it is fed into your cutting or lamination equipment.

Also, specify the intended end-use in your initial email. Do not just say “for industrial use.” Explain the mechanical stresses the fabric will face. If the fabric is for a protective suit, mention the expected abrasion cycles. If it is for a filter bag, mention the differential pressure it must withstand. Suppliers respond better to specific technical constraints than to vague category labels.

Core physical properties to verify

You need baseline measurements for every batch or lot you plan to purchase. These numbers define the fabric identity.

1. Gram Weight (GSM): Request the average and the acceptable tolerance. A fabric labeled 30 GSM should typically fall within a narrow range. If the supplier cannot confirm the tolerance, ask why. Tolerance is a measure of process stability. A tight tolerance indicates a well-calibrated machine. A loose tolerance suggests the line is running near its limits or that the fiber feed is inconsistent. For high-precision applications, such as medical packaging, a tolerance of plus or minus one GSM may be standard. For general industrial use, a wider range is often acceptable.
2. Thickness: Measure the fabric in millimeters. This is critical for packaging and cushioning applications. Thickness is influenced by GSM and the fiber diameter. Two fabrics with the same GSM can have different thicknesses if one uses a finer polymer fiber and the other uses a coarser one. Always ask for the measurement method. Is it taken with a calibrated micrometer on a hard surface or a soft indenter? The method changes the result.
3. Peltier Number: For meltblown and spunbond blends, ask for the meltblown percentage. This directly impacts filtration efficiency and breathability. The meltblown component consists of extremely fine fibers that create a dense web. A higher percentage increases particle capture but reduces air flow. You must balance these two factors based on your specific filtration requirement.
4. Burst Strength: Measured in kilopascals or pascals. This is the primary metric for filtration media. Burst strength indicates the maximum pressure the fabric can withstand before tearing. It is measured using a circular aperture and a pneumatic system. Ask for the aperture size used during testing. A smaller aperture yields a higher burst strength value for the same fabric. Standardizing the test setup is necessary for fair comparison between suppliers.
5. Air Permeability: Measured in cubic meters per hour. Higher values indicate more open structures, which are common in hygiene products but undesirable in high-efficiency filtration. Air permeability is often tested using a specific volume of air forced through a specific area of fabric. The result is expressed as cubic meters per hour at a defined pressure differential.
6. Melt Index or Melt Flow Index: This indicates the polymer melt flow. It helps predict how the fibers will behave during subsequent processing, such as lamination or welding. Melt index is a measure of the polymer’s viscosity. A lower melt index indicates a stiffer polymer that is harder to process. A higher melt index indicates a more fluid polymer that is easier to weld. If you plan to laminate the fabric, ask the supplier to confirm the melt index of the base fiber and the adhesive used.

Process parameters and production details

General specs tell you what the fabric is. Process parameters tell you how it was made. This distinction matters when you need to troubleshoot performance issues later.

Parameter	Why It Matters	Typical Red Flags
Needle Length	Determines fiber entanglement and thickness.	Vague answers or refusal to specify.
Bond Temperature	Affects bond strength and fiber damage.	No temperature range provided.
Line Speed	Influences fiber alignment and weight consistency.	Constantly changing values without explanation.
Fiber Type	PP, PE, PET, or blends change chemical resistance.	“Standard polymer” without naming the grade.
Coating	Hydrophobicity or barrier properties.	Missing data if the fabric is coated.

If a supplier provides a process parameter range that is too wide, the production process may be unstable. For example, a needle length varying by more than a few millimeters suggests poor machine maintenance. This variability can lead to inconsistent fabric quality from one roll to the next. Needle length is a physical dimension of the needle bar. If the needles wear down, the entanglement depth changes. This affects the fabric’s tear resistance and its ability to hold together under tension.

Bond temperature is equally sensitive. For thermally bonded fabrics, the temperature determines how the fibers fuse. If the temperature is too low, the bond is weak. If it is too high, the fibers melt and degrade. This causes the fabric to become brittle or sticky. Ask for the specific temperature range used for your product. A single number is less useful than a range, as it shows the control window the supplier maintains.

Line speed affects the final fabric weight. A faster line produces a lighter fabric because the fibers have less time to deposit. If the supplier changes the line speed without notifying you, the GSM will shift. This can break your packaging machines or alter your filtration performance.

Compliance and certification requirements

Your application dictates which certificates you need. A fabric for a medical device requires a different documentation trail than one for an agricultural cover.

• Medical Applications: Request ISO 13485 certification and material safety data sheets (MSDS/SDS). Ask if the fabric is biocompatible and if it passes specific bioburden tests. Bioburden refers to the amount of microbial contamination on the fabric. For sterile products, the fabric must be low bioburden to allow for effective sterilization. Ask for the specific bioburden test method and the results.
• Filtration: Ask for test reports from independent labs. Look for data on MERV ratings, particle capture efficiency, and pressure drop. MERV ratings are standardized measures of filter efficiency. However, MERV ratings are often determined at a specific dust type and air velocity. If your application uses a different dust type, such as fine chemical powder, the MERV rating may not be accurate. Ask for particle capture data at your specific air velocity.
• Food Contact: Request compliance with regulations like FDA or EU food contact material standards. These regulations limit the migration of chemicals from the packaging to the food. Ask for the specific migration test results. Do not just accept a statement of compliance. Request the actual test report.
• Automotive: Verify compliance with specific OEM requirements for headliner or sound deadening materials. Automotive OEMs have strict requirements for material flammability, VOC emissions, and acoustic properties. Ask for the specific OEM code or specification number you are targeting.

Do not accept a general “quality certificate.” Ask for the specific test method and the date of the last test. If the supplier cannot produce a test report that matches your specific request, that is a warning sign. Test reports expire. A report from two years ago may not reflect the current production process. Always request reports from the last three to six months.

Packaging and logistics data

The physical state of the fabric when it arrives matters. Ask for the following:

1. Roll Diameter and Core Size: This affects how the fabric fits your machinery. If the roll is too large, it may not fit into your unrolling unit. If the core is too thin, the roll may collapse during transport. Confirm the maximum roll diameter and the core material. Cardboard cores are standard, but some applications require steel or plastic cores for higher stiffness.
2. Inner and Outer Packaging: Confirm if the fabric is vacuum packed or banded. Vacuum packing prevents moisture ingress, which is critical for meltblown products that are hygroscopic. Meltblown fibers are extremely fine and absorb moisture easily. If the fabric gets wet, its strength drops and its filtration efficiency changes. Banded packaging is lighter but offers less protection against moisture.
3. Labeling: Ensure every roll has a label with the batch number, date, and weight. The batch number is your traceability key. If you have a quality issue, you need to identify exactly which rolls were used in your production. The label should be legible and affixed to the core.
4. Shipping Container Type: Confirm if the rolls are palletized or loose. Palletized shipments are easier to handle and reduce damage risk. Loose shipments are cheaper but require more manual handling. If you are receiving a large order, ask if the supplier offers palletization. Pallets also allow for better stacking in your warehouse.

Red flags to watch for

A supplier’s response to your technical inquiry reveals a lot about their internal processes.

• Vague Terminology: If they say “high quality” or “standard grade” without numbers, they may not track their own production data closely. Quality is a subjective term. Numbers are objective. If a supplier cannot provide numbers, they cannot prove quality.
• No Tolerance Ranges: A professional supplier knows their fabric varies slightly. They will provide a tolerance range (e.g., 30 GSM +/- 2). If they only give a single number, ask about the variability. A single number is a target, not a guarantee.
• Reluctance to Share Test Methods: If they refuse to tell you how they measured burst strength, you cannot trust the result. Test methods are standardized. If they use a non-standard method, the results are not comparable to other suppliers.
• Inconsistent Batch Data: If the specs for Batch A differ significantly from Batch B without a reason, their process control is poor. Process control is the ability to keep the machine running within a defined range. Inconsistency between batches indicates a lack of control.
• Missing Coating Data: If you requested a coated fabric but the spec sheet does not mention the coating, ask immediately. A missing coating can ruin your product. Coating is often an afterthought in spec sheets, but it is a critical functional layer.

How to structure your technical data sheet

When you receive the data, organize it into a single reference sheet. This sheet should be attached to your purchase order. If the supplier changes the process, you need to know.

Include the following fields in your master sheet:

• Product Name and Code
• Machine Model (if available)
• Fiber Type and Grade
• GSM and Tolerance
• Thickness and Tolerance
• Burst Strength
• Air Permeability
• Meltblown Content
• Coating Details
• Batch Number
• Date of Production
• Date of Last Test

Keep this sheet for at least two production cycles. If you have a quality issue, you can quickly compare the current batch against the approved sample. This makes it easier to identify whether the issue is with the fabric or your own processing. For example, if your final product is tearing, check if the burst strength of the new batch is lower than the approved sample. If it is, the fabric is the problem. If it is not, the issue is likely in your cutting or lamination process.

Also, include the supplier’s contact person on the sheet. This person should be the technical contact, not just the sales representative. Sales representatives focus on closing the deal. Technical contacts focus on solving problems. Having their direct contact information saves time when you need to clarify a spec.

Final verification steps

Before you commit to a bulk order, request a sample. Do not just look at it. Run it through your own equipment. Check the weight with a calibrated scale. Measure the thickness with a micrometer. If possible, run a small-scale performance test on your specific application.

If the sample passes, ask the supplier to confirm that the production run will use the same machine settings and fiber batch. Ask for a pre-shipment inspection report. This report should include the test results for the specific rolls that will ship to you. This final step ensures that the fabric you receive matches the specs you requested.

The sample is only a snapshot of the production process. The production run may have different fiber batches or machine settings. The pre-shipment inspection report bridges this gap. It verifies that the actual product being shipped meets the agreed specifications. Do not skip this step. It is the last chance to catch a problem before the fabric arrives at your facility.