.313 in Buna-N O-Ring Cord Stock 70A - 0.313 in Thick 100 ft

In this review of the.313 in Buna-N O-Ring Cord Stock, the bottom line is straightforward: this 70A durometer cord is for users who need a resilient, oil-resistant round sealing cord in a long spool. The reviewer finds it best for workshop fabricators, hydraulic and pneumatic maintenance, and hobbyists who make custom O-rings or repair rubber tires because of its consistent thickness and compatibility with petroleum-based fluids. The cord's combination of Buna-N (Nitrile) material and a 70A hardness delivers dependable abrasion and tear resistance across common service temperatures, making it a practical choice when chemical resistance to oils matters.

Key Features

• Material: Made from Buna-N (Nitrile, NBR) to provide strong resistance to petroleum and many hydraulic fluids used in industrial service.
• Durometer: 70A hardness gives a balance of flexibility and firmness suitable for formed O-rings and seals that must retain shape under compression.
• Temperature Range: Rated for a wide service window so it can operate from cold starts to hot equipment, suitable for many shop and field environments.
• Length and Size: Supplied on a 100 ft spool at 0.313 in thickness, allowing many replacement O-rings or long runs of cord for larger seals without repeated purchasing.
• Made in USA: Domestic manufacture tends to mean consistent compound and quality control across the spool for predictable cutting and gluing.

Who It's For

This cord is aimed at maintenance technicians, hydraulic and pneumatic service teams, and home mechanics who need a reliable nitrile cord for making replacement O-rings, sealing repairs, or even nonstandard uses like rubber tire repair where oil resistance and durability matter. It is also suitable for fabricators who prefer to form custom seals from a long spool rather than buying many preformed sizes.

Those who need resistance to ozone, sunlight, or strong solvents such as acetone and certain esters should look elsewhere; Buna-N is not the best choice for continuous UV exposure or for applications involving aggressive polar solvents. If extreme low-temperature flexibility beyond the listed range is required, a different elastomer may be preferable.

Pros & Cons

Pros

• Good resistance to petroleum and many hydraulic fluids, making it practical for industrial sealing work.
• Durable 70A durometer that balances tear resistance with enough flexibility to form custom O-rings.
• Long 100 ft spool gives strong value for frequent users and reduces spool changes for shops.
• Consistent thickness and easy glueability noted by customers for forming and repairing seals.

Cons

• Not resistant to ozone, UV, and some solvents like acetone and ethers, limiting outdoor or harsh-chemical use.
• The mixed feedback on exact fit and leak resistance for some custom applications means careful sizing and finishing are needed.

Specifications

Material	Buna-N (Nitrile, NBR)
Durometer	70A
Cross Section	Round cord, 0.313 in thickness
Length	100 ft spool
Temperature Range	Approximately -40 degrees F to 212 degrees F
Compatibility	Petroleum, HFA/HFB/HFC fluids, vegetable oil, alcohols, acids, aliphatic hydrocarbons
Origin	Made in the U. S. A.

Our Verdict

The.313 in Buna-N O-Ring Cord Stock is a solid, cost-effective choice for anyone making custom seals or replacing worn O-rings in oil-exposed systems; its 70A compound and long 100 ft spool deliver good durability and value. Choose a different elastomer if your application sees constant ozone, UV, or aggressive solvents, but for general hydraulic, pneumatic, and workshop sealing needs this cord performs reliably.

Frequently Asked Questions

Can this cord handle hydraulic oil exposure?
Yes, Buna-N is compatible with petroleum and many hydraulic fluids listed, making it suitable for common hydraulic sealing tasks.

Is it safe for outdoor use?
No, Buna-N is vulnerable to ozone and UV, so prolonged outdoor exposure or ozone-rich environments are not recommended.

Can you form and glue O-rings from the spool?
Yes, reviewers note it is easy to glue into O-rings and the spool length allows multiple custom sizes to be formed.