What do typical properties on a TDS mean, and what do they not?
Summary
Typical properties on a TDS are average test values from past production that describe a product but do not guarantee any single batch. They are for comparing products. What the supplier commits to sits in its sales specification, and what one batch measured sits in its certificate of analysis (CoA), so build purchase specifications from those documents.
One film supplier describes data sheet values as usually average values based on the run history of the product (Tekra, accessed 2026).
One maker states its data sheet values are for product selection and are not necessarily the minimum values during normal testing (Chase Corporation, accessed 2026).
IEC TR 60893-4 says its typical values "should not be considered as specification requirements" (IEC, 2014).
ICH Q7 states that a CoA should list each test performed, the acceptance limits and the numerical results obtained (ICH, 2000).
How are typical properties on a TDS measured and reported?
Typical properties on a technical data sheet (TDS) are measured by the maker's own laboratory with named test methods, then reported as one representative number per property, usually an average of past production. One film supplier explains that these values are usually averages based on the run history of the product and change little during the life of the product (Tekra, accessed 2026). The same supplier notes that data sheet properties do not normally carry a range or tolerance (Tekra, accessed 2026).
Read three things next to each typical value before you use it. First, the test method, such as an ASTM or ISO number, because two makers can report the same property by different methods and the numbers will not compare. Second, the test conditions, such as temperature, cure schedule or specimen thickness. Third, the unit and basis, such as weight percent against volume percent.
A typical value without a method or condition tells you the order of magnitude and little more. Whether it comes from many lots or a few is rarely stated on the TDS, so ask the supplier when the number matters to your decision.
How do typical properties differ from specification limits and certificate of analysis results?
Typical properties differ from specification limits and certificate of analysis results in what they bind: a typical value describes the product, a specification limit is what each lot must meet, and a CoA result is what one lot measured. ICH Q7, the GMP guide for active pharmaceutical ingredients, defines a specification as a list of tests, procedures and acceptance criteria to which a material should conform to be considered acceptable (ICH, 2000).
The table below shows which TDS value labels bind the supplier and what to ask for instead.
TDS value label | What it means | Can it go into a purchase spec? | What to ask for instead |
|---|---|---|---|
Typical | Average from past production; no lot is promised to match (Tekra, accessed 2026) | No | The supplier's sales specification |
Nominal | Target or design value, often without a tolerance | No, unless a tolerance is agreed | The tolerance in writing |
Minimum or maximum | One-sided limit, if the document says it is a specification | Yes, if the supplier confirms it binds | Confirmation that it is a sales spec limit |
Specification limit | Range each lot must meet, from a controlled document | Yes | The current revision of that document |
CoA result | Measured value for one batch against stated limits (ICH, 2000) | No; it is evidence of conformance | A CoA with every lot |
The key row is the first: a typical value does not go into a purchase specification as a limit. The rows differ in who stands behind the number. A typical value is a description the maker publishes for selection. A specification limit is a commitment the maker controls by revision. A CoA result is evidence for one lot, and it only means something when it is read against the specification revision that was in force when that lot was made, so request both documents for every product you buy against limits.
What goes wrong when a customer writes typical TDS values into a purchase specification?
When a customer writes typical TDS values into a purchase specification, normal lots can fail incoming inspection, because an average sits inside the spread of production rather than at its edge. One film supplier reports receiving specifications plainly written from its data sheet values and says those values have little meaning as a guide to manufacturing the product (Tekra, accessed 2026).
Three problems follow. First, rejections: if the typical value is an average, some normal lots will measure on the wrong side of it (reasoning from the definition, not a measured rate). Second, method mismatch: your laboratory may test by a different method or condition than the maker, so even conforming lots read differently. Third, rounding disputes: ASTM E29-22 describes two ways to compare a result with a limit and says a reference to the practice is valid only when either the absolute method or the rounding method has been indicated (ASTM, 2022).
Some makers say this on the TDS. A silicone sealant data sheet reported by a specifications newsletter carries the note that its typical values "are not intended for use in preparing specifications" (4specs, 2023).
When should you ask for a sales specification or a certificate of analysis instead of typical properties?
Ask for a sales specification instead of typical properties when you are writing a purchase specification, an incoming inspection plan or a customer commitment, and ask for a certificate of analysis with every lot that you accept against those limits. One film supplier calls the manufacturer's specification a controlled document with a range or tolerance for each property, distributed only on request (Tekra, accessed 2026).
Use typical properties only to shortlist and compare products. Once a product is chosen, request the sales specification, check that it covers each property that matters to your use, and negotiate limits for any missing property. The same supplier advises that a product specification should contain only the properties that are important to the application (Tekra, accessed 2026).
Keep the documents for one product together and dated, because a CoA is checked against the specification revision that applied to that lot. A practical filing scheme for many suppliers is covered in how a distributor should organize TDS, SDS and CoA files. In Lubinpla, the Dataroom tags TDS and CoA files as separate document types, so filtering by document type and product type lists both documents for a product line together.
Typical properties vs nominal and guaranteed values on a TDS: how do you tell them apart?
You tell typical, nominal and guaranteed values on a TDS apart by the column heading, the footnote and any warranty statement, and when they disagree you ask the supplier which one binds. Labels on a TDS are not standardized, so the same sheet can mix them.
One solvent distributor's TDS lists maximum and minimum limits in a column headed "Specification", then states below the table that "These specifications are typical and represent the quality of our product in general" (A.G. Layne, 2023). The same sheet says the company warrants that its products will meet its written specifications (A.G. Layne, 2023). A reader cannot tell from the page alone whether those limits are the written specification.
When a TDS is ambiguous in this way, ask for the written sales specification by name and revision. Treat any value as typical until a controlled document or a signed agreement says it is a limit. Standards use the same distinction: IEC TR 60893-4 publishes typical values for laminated sheets to give general guidance, separate from the specification requirements in the product standards (IEC, 2014).