Durometer is a measure of hardness — how much a material resists being pressed into. On a roll cover, it's one of the most consequential specs you'll choose. Too soft and the cover deforms, wears fast, or can't carry the load. Too hard and it loses grip, marks the product, or transmits every imperfection in the nip. The right number is the one matched to what the roll actually has to do.
Roll cover hardness is measured on the Shore (durometer) scale, and two ranges matter for industrial rolls:
Shore A covers everything from soft, flexible covers to firm ones. A gummy pencil eraser is around 40 Shore A; a shopping-cart wheel is around 90 Shore A. Most rubber roll covers live somewhere on this scale.
Shore D picks up where Shore A tops out, measuring hard materials — rigid polyurethanes and hard covers. The two scales overlap at the top: roughly 90 Shore A is near 40 Shore D. When a cover needs to be genuinely hard, it's specified in Shore D.
Softer covers (roughly 20–50 Shore A) conform to the surface they touch. They create a wider nip footprint, handle delicate materials gently, absorb irregularities, and grip well. The trade-off is that they deflect more under load and can wear faster in abrasive service.
Firmer covers (roughly 60–90 Shore A) resist deformation, carry higher loads, hold tighter tolerances, and last longer against abrasion. The trade-off is less conformability and less forgiveness — a hard cover telegraphs any flaw in the nip and can mark softer product.
Hard covers (into Shore D) are for high-load, high-precision, or heavy-wear jobs where the surface must not deform at all.
Use this as a starting point, not a final spec — the correct hardness always depends on your specific loads, speeds, and material. But this is the general lay of the land:
| Hardness range | Feel | Typical use |
|---|---|---|
| 20–40 Shore A | Soft | Delicate handling, maximum conformability, gentle nip on sensitive materials |
| 40–60 Shore A | Medium | General-purpose nip rolls, balanced grip and durability |
| 60–80 Shore A | Firm | Higher loads, traction and pull rolls, tighter tolerances |
| 80–95 Shore A | Hard | Heavy loads, minimal deflection, abrasive service |
| Shore D range | Rigid | High-load, high-precision, or severe-wear applications; hard polyurethane covers |
A number alone isn't a spec. Two covers at the same durometer can behave completely differently depending on the compound. Hardness sets how the cover carries load and grips — but the chemistry decides how it survives heat, chemicals, and wear. You need both right.
Start with three questions: What load does the nip carry? Higher loads generally push you firmer. How sensitive is the product? Delicate or easily-marked material pushes you softer. How abrasive is the service? Heavy wear pushes you firmer and toward tougher chemistries.
Then look at your current cover. If it's deforming, glazing, or wearing unevenly, the durometer may be wrong for the load. If it's marking product or losing grip, it may be too hard. The failure mode on the old roll is usually the best clue you have.
Picking durometer from a chart gets you in the neighborhood. Getting it exactly right — for your load, your line speed, your material, and your chemistry — is what separates a cover that lasts from one that doesn't. That's the part we do with you, and we test it before it ships. When the Arthur name goes on a roll, we stand behind it.
Tell us the application, the load, and how your current cover is behaving. Our chemist will recommend the right durometer and the right compound to go with it. No cost, one business day.
Get Your Free Roll Analysis Call (901) 775-0513Tell us about your application: the line, the compound that's failing, the failure mode, and what you're running through it. Our chemist will analyze and respond with a specific recommendation — not a generic pitch.