.750 in Buna-N O-Ring Cord Stock, 70A Durometer - 25 ft

In this review the focus is on a practical, general-purpose O-ring cord stock for repair and prototyping work. The.750 in Buna-N O-Ring Cord Stock with a 70A durometer and a 25 ft length is best for users who need a resilient, oil-resistant rubber cord that is easy to cut, glue, and form into replacement O-rings or custom seals. The reviewer found the material's balance of flexibility and firmness - along with compatibility with common petroleum and hydraulic fluids - to be the single biggest reason to buy for maintenance shops, hobbyists, and small fabricators.

Key Features

• Buna-N material: Offers good resistance to petroleum, HFA, HFB, HFC fluids and vegetable oils, making it suitable for many hydraulic and fuel-related sealing tasks.
• 70A durometer: Provides a firm but flexible sealing surface that holds shape well and resists compression set in many static and low-dynamic seals.
• Wide temperature range: Usable across typical service temperatures so it works in many shop and equipment environments.
• 25 ft length: Supplies enough cord for multiple rings or longer runs without frequent reordering, convenient for small shops and DIYers.
• Round cross-section: Simple round profile makes it straightforward to form and glue into O-rings or to use as a round gasket element.

Who It's For

This cord stock is aimed at maintenance technicians, hydraulic and pneumatic repair shops, and home mechanics who need a dependable, oil-tolerant elastomer for making replacement O-rings or custom seals. It is especially useful when a resin or rigid material would not conform to mating parts.

It is less appropriate for applications exposed to strong solvents like acetone, for use near ozone-producing equipment, or for long-term UV outdoor exposure; users with those conditions should select a different elastomer formulated for solvent or ozone resistance.

Pros & Cons

Pros

• Good chemical compatibility with petroleum and many hydraulic fluids, useful for seals in fluid systems.
• Durable feel with resistance to abrasion and tear reported by users, supporting longer in-service life.
• Easy to glue and form into rings, which customers noted makes replacement O-ring construction straightforward.

Cons

• Not resistant to acetone, ethers, esters, ozone, or prolonged UV exposure, limiting use in some environments.

Specifications

Material	Buna-N (Nitrile, NBR)
Cross Section	Round (.750 in diameter)
Durometer	70A
Temperature Range	-40 degrees F to 212 degrees F (usable listed to -30 F to 250 F in description)
Length	25 ft piece
Made in	U. S. A.

Our Verdict

The.750 in Buna-N cord stock is a practical, cost-effective choice for those making replacement O-rings or custom seals where oil and hydraulic fluid resistance matter. It delivers a good balance of firmness, durability, and ease of use, making it solid value for maintenance shops and DIYers, provided the environment does not expose the rubber to strong solvents or ozone.

Frequently Asked Questions

Can this cord handle hydraulic oil?
Yes, Buna-N is compatible with many petroleum and hydraulic fluids such as HFA, HFB, and HFC types noted in the product details.

Will it withstand outdoor UV exposure?
No, Buna-N is vulnerable to ozone and UV weathering, so it should not be used for prolonged outdoor exposure.

Is it easy to glue into O-rings?
Customers report the material bonds and forms easily, making it straightforward to cut and glue into replacement O-rings.