.275in Buna-N O-Ring Cord Stock 70A Durometer - 500 ft spool

In this review of the.275in Buna-N O-Ring Cord Stock, the bottom line is simple: this is a workhorse sealing material for projects that need reliable oil and hydrocarbon resistance. The reviewer found the 70A durometer and round cross-section well suited to cutting replacement o-rings, tyre repairs on small wheels, and custom seals for hydraulic and pneumatic fittings. Made in the U. S. A., the 500 ft spool offers long runs for frequent users, and its compatibility with common petroleum and vegetable oils is the single biggest reason to choose it for industrial and hobby sealing tasks.

Key Features

• Material: Buna-N (Nitrile) provides good resistance to petroleum, HFA/HFB/HFC fluids and aliphatic hydrocarbons for confident use around oils and fuels.
• Hardness: The 70A durometer balances flexibility and firmness, making the cord easy to glue and form into replacement o-rings while holding shape under compression.
• Temperature range: Rated for a wide range of service temperatures so it performs in cold conditions down to around -40 degrees F and up to about 212 degrees F for many applications.
• Length and format: The 500 ft spool supplies enough cord for many cuts and projects, reducing waste and repeated purchases for shops and maintenance teams.
• Durability: Buna-N offers abrasion and tear resistance with useful compression set characteristics for repeated sealing cycles.
• Made in the U. S. A.: Domestic manufacture ensures consistent quality control and predictable material properties for professional use.

Who It's For

This cord stock is ideal for maintenance engineers, hobbyists, and small fabricators who need a reliable o-ring cord for making custom seals, repairing rubber tires on small equipment, or producing gasketing for fluid-handling parts. The spool format suits users who will cut many rings or need continuous lengths.

It is less suitable for applications exposed to strong ozone, UV sunlight, or solvents like acetone and certain ethers and esters; users requiring long-term outdoor weathering resistance or compatibility with aggressive ketones should consider alternate elastomers.

Pros & Cons

Pros

• Good compatibility with petroleum and many hydraulic fluids, making it practical for oil-handling systems.
• 70A durometer offers a useful balance of resilience and ease of assembly when forming rings or bonding with adhesive.
• Large 500 ft spool delivers strong value for shops and repeat consumers who cut many seals.
• Customers report strong fit, adhesive ease, and long-term durability in routine use.

Cons

• Not recommended for prolonged exposure to ozone, UV light, or certain solvents such as acetone and some esters.
• Temperature limits mean extreme high-heat applications above the rated range may require a different compound.

Specifications

Our Verdict

The.275in Buna-N O-Ring Cord Stock is a practical, cost-effective choice for making replacement o-rings and custom seals when resistance to oils and common hydraulic fluids is required. For shops and hobbyists who cut many rings, the 500 ft spool and 70A firmness offer reliable performance and good adhesive compatibility, making it a strong value for general industrial sealing needs.

Frequently Asked Questions

Is this cord compatible with hydraulic oil?
Yes, Buna-N is compatible with many petroleum-based hydraulic fluids and HFA/HFB/HFC types listed for typical nitrile use.

Can I use this outdoors?
It can be used outdoors for short periods, but prolonged exposure to UV and ozone will degrade the material, so a UV-stable compound is better for long-term outdoor service.

Will it bond well with adhesives?
Customers report that the 70A durometer bonds easily with common rubber adhesives, making it straightforward to form glued o-rings and repairs.