Natural Rubber O-Rings

What natural rubber is, and where it is chosen

Natural rubber is the vulcanized latex of the rubber tree, chosen for its resilience, tensile strength, tear strength and abrasion resistance; the Parker® handbook's comparison table rates it excellent for abrasion, dynamic service and tensile strength (Table 2-2). In seals it serves water, alcohols, glycols and alkalis, with fair results in weak organic acids, in glands that see impact, flexing or abrasion (Parker section VII ratings). The Parker handbook prints no text temperature figure for it. The range on this page, -50 C to 70 C, is Apple Rubber's printed standard-compound range of -58 F to 158 F (dry heat only), converted to Celsius; it is one maker's printed figure, and the compound sheet you order from governs.

Where natural rubber fails

Petroleum oils, fuels, aromatic solvents and ketones attack it, and ozone cracks it: the Parker handbook rates it unsatisfactory in hydraulic oil, gasoline, diesel, benzene, acetone and ozone, and Apple Rubber notes its poor compression set. Where the medium is oil, nitrile; where the seal sits outdoors, EPDM; where heat is the problem, silicone or FKM. Natural rubber is the usual fit where the seal is flexed or abraded in water or air. SBR, the synthetic developed as its substitute and used today mainly in tires, has similar compounded properties.

How to specify

Send the AS568 dash number or the inside diameter and cross-section, the durometer, the medium and the temperature, and whether the gland flexes or sees abrasion. The quote names the compound your print or your engineering specifies and sends its datasheet with the range it carries.

Sizes and forms we supply

All 369 AS568 sizes (349 general-purpose dash sizes plus the 20 boss-seal sizes) and the ISO 3601 metric series, in the durometers listed above; O-ring cord for rings spliced and vulcanized by the maker in odd diameters (static service only), where the compound is made as cord. The AS568 chart and the AS568 sizes in millimeters carry the dimensions, and the dash number guide explains the numbering.

Sources: Apple Rubber, Seal Design Guide, Natural Rubber page (standard-compound range, dry heat only), read 2026-09-27; Parker O-Ring Handbook ORD 5700, Table 2-2 (comparison of elastomer properties, page 2-9) and section VII compatibility ratings, natural rubber column, read 2026-09-27; AS568 size count, 369 sizes (349 general-purpose plus 20 boss): Parker O-Ring Handbook ORD 5700, section IX size tables (Series 2-XXX and the 3-9XX boss table), read 2026-09-27; ASTM D1418; ASTM D2000 (documents named, not reproduced); Parker O-Ring Handbook ORD 5700, page 2-10 (hardness guidance), read 2026-09-25; Apple Rubber, Seal Design Guide, Styrene Butadiene page, read 2026-09-27.

Parker is a trademark of Parker Hannifin Corporation. Apple Rubber is a trademark of its owner; no affiliation or endorsement is implied.