20 mesh vs 30 mesh rubber powder: sizes in mm
ASTM No.20 means a 0.85 mm sieve opening; No.30 means 0.60 mm. Higher mesh is finer. These dimensions are not proof that every particle in a commercial grade passes that sieve.
Explore the questionsHigher mesh number, smaller opening
20 mesh reference
ASTM No.20: 850 micrometres, or 0.85 mm, nominal sieve opening.
30 mesh reference
ASTM No.30: 600 micrometres, or 0.60 mm, nominal sieve opening.
Name the specification
Agree the sieve standard, permitted oversize and finer fractions. A mesh name is not a full distribution.
Understanding mesh
Choose a question to read more.
Read mesh and millimetres together
Millimetres measure the opening; the sieve designation identifies it within a standard series.
Buyers often use “20 mesh” and “30 mesh” as shorthand. Written orders should identify the standard and the actual opening so supplier and buyer are discussing the same measurement.
| ASTM E11 designation | Nominal opening | In millimetres |
|---|---|---|
| No.20 | 850 µm | 0.85 mm |
| No.30 | 600 µm | 0.60 mm |
These dimensions are shown in test-sieve manufacturer Gilson’s No.20 and No.30 specifications. They describe the screen, not the average particle size in a bag.
Bedrock offers 20 mesh and 30 mesh black rubber powder. The available material must still be discussed against your required size distribution.
Does 30 mesh mean everything passes?
Not automatically. A commercial designation can allow material retained on the named sieve.
A mesh label is not a guarantee of 100% passing. The public summary of ASTM D5644, a test method for recycled particulate rubber, describes product mesh designations with permitted retained material. The applicable limit depends on the defined classification and method.
For an order, write the permitted percentage passing or retained on each relevant sieve. Include an oversize limit and any restriction on very fine material. Two powders can share a trade name while containing different proportions of particle sizes.
Read our sieve-analysis guide before comparing a supplier’s result with your acceptance table. Do not mix cumulative passing and individual retained percentages as though they mean the same thing.
Choose powder for the process
Finer is not automatically better. Start with the formulation you need to run.
When a specification already exists
Send the complete particle-size requirement, not only the preferred mesh name. Include the intended use, test method and other acceptance checks your technical team requires. A material can meet one size limit and still fail a different requirement.
When you are developing a formulation
Agree the candidate grade with your formulator or process specialist, then evaluate it in the actual system. A sieve-opening comparison cannot establish dosage, processing conditions or finished-product performance.
For rubber-modified asphalt, the chosen process has its own material requirements; “30 mesh” is not a complete asphalt-modifier specification. For moulded or compounded products, assess the powder in your formulation rather than assuming one mesh grade can replace another unchanged.
Specify the powder you need to run
Send Bedrock your target mesh or sieve table, intended process, quantity and destination. We can discuss the available powder against your formulation's acceptance limits, sample evaluation and the information needed for that order.
Discuss your powder specificationCommon questions
Is 30 mesh finer than 20 mesh?
Yes, the ASTM No.30 reference sieve has a smaller opening than No.20. The full particle distribution still needs to be agreed for the powder being supplied.
Does Bedrock publish a measured curve for these grades?
The published mesh names are nominal commercial grades, not a measured sieve curve. Ask which grade-specific information can be confirmed for your proposed order.