Sieve analysis: how to read a rubber grade
A sieve analysis shows a sample's weight distribution across particle sizes. It does not prove chemical safety, cleanliness or that the whole shipment matches. Agree the method, sampling and permitted distribution.
Explore the questionsRead the whole distribution
Range
A name such as 1–3 mm is not a complete particle-size specification.
Distribution
Retained and passing percentages show where the sample's weight sits.
Agreement
The method, sampling and acceptance limits must refer to the same requirement.
Reading the results
Choose a question to read more.
Retained and passing mean different things
Retained is held on a sieve; passing is the total below its opening
A weighed sample is separated using specified sieves and a defined test procedure. The collected fractions are weighed to calculate percentages.
Read the column heading first
Individual retained means the percentage held on one sieve. Cumulative retained includes that sieve and all coarser sieves. Percent passing is the portion passing that opening. It equals 100 minus cumulative retained, using the same calculation basis.
RETSCH’s methods guide explains the measurement. For recycled vulcanised rubber, ASTM D5644-23 covers mechanical vibratory sieve testing for particles of 90 micrometres and larger. The buyer and laboratory should confirm the applicable method.
A small example you can read at a glance
Illustrative numbers only: 98% passing 3 mm and 4% passing 1 mm leave 94% between them
Teaching example only, not Bedrock material data or an acceptance limit.
| Sieve opening | Cumulative passing |
|---|---|
| 3 mm | 98% |
| 2 mm | 42% |
| 1 mm | 4% |
In this example, 2% is retained at the upper boundary, 4% passes the lower boundary and 94% passes 3 mm but is retained at 1 mm. The 2 mm result tells you more about the distribution inside the range.
None of those figures is automatically acceptable. The end-use specification determines the permitted percentages.
Six checks before you compare offers
Check identification, sampling, method, boundaries, reporting basis and other quality requirements
- Identify the material. Is the report for a reference sample, a production run or a named lot? Check the date and grade.
- Check sampling. Ask how the test portion represents the material being offered. One convenient scoop is not automatically representative.
- Match the method. Confirm the standard, sieve openings and test conditions used for both the result and your specification.
- Include both boundaries. Look for the oversize and fines fractions, not only the sizes in the middle.
- Read the reporting basis. Distinguish retained from passing and clarify rounding, missing fractions or unexplained mass differences.
- Keep other requirements separate. Size analysis does not measure residual wire, textile, moisture or chemical compliance.
Sampling matters even when laboratory work is correct. RETSCH’s sampling guidance explains why the test portion must represent the bulk material.
Use our nominal granule ranges to shortlist a grade, then provide the sieve limits required by your process.
Turn your sieve limits into an enquiry
Send Bedrock the required sieve openings, permitted passing or retained percentages, test method, end use, quantity and destination. We will discuss the proposed grade and establish which measurements or documents are available. A buyer sample and any independent testing need an agreed scope.
Send your sieve requirementsCommon questions
Does 1–3 mm mean every particle measures between 1 and 3 mm?
Do not assume that from a grade name alone. Ask for the permitted distribution at the boundary and intermediate sieves, measured by the agreed method.
Does a sieve report establish that a product is safe?
No. It measures particle-size distribution. Application performance, chemical requirements and other quality limits need their own evidence.
Is a report supplied with every Bedrock lot?
That is not a standard commitment stated here. Required measurements, documents, sampling and testing must be confirmed for the proposed order.