.295 in Buna-N O-Ring Cord Stock 70A - 25 ft Length

In this review of the.295 in Buna-N O-Ring Cord Stock, the bottom line is clear: this 70A durometer nitrile cord is best for DIY seal repairs and light industrial sealing where petroleum compatibility and abrasion resistance matter. The reviewer found it reliable for making replacement o-rings and custom seals, with the main reason to buy being its consistent hardness and broad compatibility with oils and hydrocarbons. It is a plain, functional product made in the U S A that performs predictably across typical workshop temperatures.

Key Features

• Material: Buna-N (Nitrile) composition gives good resistance to petroleum oils and many hydraulic fluids used in workshop and industrial settings.
• Hardness: 70A durometer provides a balance of elasticity and firmness that seals well without feeling too stiff for hand-cut o-rings.
• Temperature range: Rated for use across broad temperatures, making it suitable for applications from cold storage to warm engine bays within the specified limits.
• Length and size: Supplied as a 25 ft piece in a 0.295 in round cross section, which is convenient for cutting multiple custom o-rings and short runs of cord seals.
• Durability: Buna-N offers good tensile and abrasion resistance so cut rings and strips hold up well under repeated use when not exposed to ozone or strong solvents.
• Origin: Made in the U S A, which aids consistency and traceability for workshop purchases.

Who It's For

This cord stock is aimed at hobbyists, maintenance technicians, and small shops that need to fabricate replacement o-rings, seals, or bumpers that will see exposure to petroleum-based fluids, vegetable oil, or common hydraulic fluids. It works well for projects like small pneumatic fittings, fuel system seals, and even custom rubber tire repairs mentioned by other users.

Those who should look elsewhere include users who require long-term outdoor exposure to sunlight or ozone resistance, or applications that will encounter strong solvents such as acetone, ethers, or esters. For extreme low-temperature elastomers or specialty chemistries, select a purpose-made compound instead.

Pros & Cons

Pros

• Good compatibility with petroleum, HFA/HFB/HFC fluids, vegetable oil, and many alcohols.
• 70A hardness balances flexibility and compression resistance for reliable sealing.
• Durable against abrasion and tear in typical workshop uses, with easy adhesion when gluing rings.
• Available as a long 25 ft piece in a consistent 0.295 in diameter for multiple cuts.

Cons

• Not suitable for exposure to ozone, sunlight, or UV - will degrade in outdoor or ozone-rich environments.
• Vulnerable to certain solvents such as acetone and esters, so not ideal for all chemical applications.

Specifications

Material	Buna-N (Nitrile, NBR)
Cross section	Round cord, 0.295 in thickness
Durometer	70A
Length	25 ft piece
Temperature range	Approx -40 F to 212 F (-40 C to 100 C)
Compatibility	Petroleum, HFA/HFB/HFC fluids, vegetable oil, alcohols
Origin	Made in the U S A

Our Verdict

The.295 in Buna-N O-Ring Cord Stock is a pragmatic choice for users needing an affordable, durable nitrile cord for oil- and hydrocarbon-exposed seals. Its 70A hardness and 25 ft length make it good value for fabricating multiple replacement rings and repairs, but avoid it for prolonged UV or ozone exposure and for applications requiring solvent resistance beyond standard oils.

Frequently Asked Questions

Can this cord be used with petroleum-based fuels?
Yes; Buna-N is compatible with petroleum and many hydrocarbon fluids, making it suitable for fuel system seals in appropriate temperature ranges.

Is the cord suitable for outdoor use?
No; Buna-N is vulnerable to ozone, sunlight, and UV, so it is not recommended for long-term outdoor exposure.

What is the best use for the 70A hardness?
70A is a versatile hardness for hand-cut o-rings and seals that need a balance of flexibility and compression resistance in general workshop and hydraulic applications.