.562 in (9/16 in) Buna-N O-Ring Cord Stock - Durable Seal

In this review the reviewer tested the.562 in (9/16 in) Buna-N O-Ring Cord Stock to see whether it delivers reliable sealing and easy handling for general industrial and DIY repair tasks. The bottom line: this cord stock is for users who need a mid-hardness, oil-resistant round cord that bonds and shapes into custom o-rings or seals. Its single biggest selling point is consistent material performance - a 70A Buna-N formulation that handles common petroleum and hydraulic fluids while remaining tough against abrasion and compression set.

Key Features

• Buna-N construction: Provides solid resistance to petroleum, HFA, HFB and HFC fluids so it is suitable where oil exposure is expected.
• 70A durometer: A balanced hardness that holds shape under compression while remaining flexible enough to form custom o-rings and seals.
• Wide temperature range: Rated for typical service from around -40 degrees F to 212 degrees F, covering most workshop and equipment environments.
• Made in the U.S.A.: Manufactured domestically for consistent quality control and material traceability.
• Round cross section: The cord's round profile simplifies cutting, gluing, and rolling into replacement o-rings or tire-type repairs.

Who It's For

The Buna-N cord stock is best for maintenance technicians, hobbyists, and fabricators who need a reliable replacement material for seals exposed to petroleum-based fluids or vegetable oils. It is practical for rebuilding custom o-rings, small pneumatic seals, and even rubber tire replacements mentioned by customers.

Those who require resistance to solvents such as acetone or prolonged outdoor UV exposure should look elsewhere, because Buna-N is vulnerable to acetone, ethers, esters, ozone and sunlight and is not recommended for ozone-producing environments or constant UV exposure.

Pros & Cons

Pros

• Good compatibility with petroleum and hydraulic fluids, making it useful in many industrial fluids applications.
• Durable 70A hardness that resists abrasion and compression set for longer seal life.
• Easy to glue and form, with customers noting good fit and adhesive ease when making custom o-rings.

Cons

• Not suitable for use with acetone, ethers, esters, ozone or prolonged sunlight exposure, limiting outdoor and certain chemical uses.

Specifications

Our Verdict

The.562 in Buna-N cord stock is a solid, cost-effective choice for anyone needing oil-resistant round cord for making or repairing o-rings and seals. Its 70A hardness and domestic manufacture deliver dependable durability and ease of use, though it should be avoided in solvent-rich or high-UV environments. For general shop and hydraulic seal work it represents good value and practical performance.

Frequently Asked Questions

Can this cord be used with petroleum-based hydraulic oil?
Yes. Buna-N is compatible with petroleum and many hydraulic fluids listed, making it suitable for those applications.

Is the cord resistant to sunlight and ozone?
No. Buna-N is vulnerable to ozone and prolonged UV exposure, so it is not recommended for outdoor or ozone-generating environments.

What is the hardness and how does it affect use?
The cord is 70A durometer, which balances flexibility and firmness for making reliable custom o-rings and seals.