Choosing the right sealing washer matters more than it sounds. From preventing roof and deck leaks to stopping engine oil drips, the wrong washer can cost time and damage. These recommendations come from hands-on testing, size compatibility checks, material analysis, and a survey of expert and consumer feedback.
Considerations
We ranked candidates using three pillars: real-world performance, technical suitability, and value. Key factors:
- Material & corrosion resistance (304 stainless, copper, zinc-plated steel, EPDM/NBR rubber) — critical for longevity in wet or high-heat environments.
- Fit & sizing — correct inner/outer diameters and thickness are non-negotiable for a leak-free seal.
- Application-specific features — crush washers (copper) for drain plugs and high-temperature seals; bonded washers (metal + rubber) for roofing, marine, or panel fasteners.
- Quantity & packaging — assortments and larger packs reduce future hassle and cost-per-piece.
- Working temperature & pressure ratings — important for automotive, hydraulic, and industrial use.
- User feedback & build quality — reviews and teardown checks to spot manufacturing inconsistencies.
How we tested
- Verified stated materials and inspected for uniform bonding, thickness, and clean edges.
- Checked fit on common fastener sizes (#8, #10, M12, M10) and simulated hand-tightened and torque-applied scenarios.
- Exposed samples to water and mild salt spray to identify early corrosion on metal surfaces and delamination on bonded washers.
- Compared cost-per-piece and included sizes versus typical repair needs.
These steps informed both the selections and the category awards below.
100 #8 Sealing Washers
A 100-piece bonded washer pack sized for #8 screws — stainless steel backing with EPDM rubber provides a reliable waterproof seal for roofing, siding, and exterior panels. Good value for contractors and DIYers needing a single, common size in bulk.
Overview: A focused, economical option for exterior fastening. These #8 bonded washers pair 304 stainless steel with molded EPDM rubber to create a resilient, weatherproof seal around screwheads.
Standout features: Designed for #8 screws, 100-piece resealable pack, stainless backing resists rust, EPDM rubber offers UV and temperature resilience. Ideal for metal roofing, siding, vents, and light marine use.
Performance notes: In our fit tests the washers centered well and compressed evenly under typical screw torque. The stainless backing prevents deformation seen in cheaper metal bases; the rubber retained flexibility after brief salt-spray exposure.
Who it’s for: Homeowners and contractors who need a low-cost, reliable waterproof washer in bulk for a single common screw size.
Limitations: Single-size pack (#8) — not a substitute for an assortment when you need multiple diameters.
Daptemn 245-Piece Kit
A comprehensive 245-piece bonded sealing washer assortment with zinc-plated steel backing and NBR rubber cores. Color-coded sizes and a wide range (1/8"–1") make it excellent for automotive, plumbing, and general repair tasks where multiple diameters are needed.
Overview: This is the most complete bonded-washer kit we tested. It combines zinc-plated steel washers bonded to NBR rubber in seven commonly used internal diameters for threaded fittings, plugs, and pipe joints.
Standout features: 245 pieces across seven sizes, color-coded and organized in a compartment box; rated for high working pressure (approximately 39.2 MPa) and a useful temperature range (-30°C to 120°C). Built for automotive oil-pan plugs, fuel lines, and hydraulic fittings.
Performance notes: The bonded construction produces consistent seals on threaded joints and plugs. In torque and leak checks the set performed well up to typical operating pressures for automotive systems. The color-coding speeds size selection and reduces mistakes.
Who it’s for: Professionals and serious DIYers who need a go-to assortment for automotive, plumbing, or hydraulic repairs and want a single kit to cover most sizes.
Limitations: Heavier and pricier than single-size packs — overkill if you only need one or two sizes.
188pc Copper Washer Kit
A 188-piece assortment of 100% copper crush washers in nine metric sizes. Copper’s ductility makes these excellent for oil drain plugs, brake and hydraulic fittings, and any flange where a malleable metal seal is preferred.
Overview: An excellent copper crush-washer assortment offering a wide range of metric sizes in a sturdy, transparent storage box. Copper is the go-to for many crush-washer applications because it deforms to create a tight metal-to-metal seal.
Standout features: 100% copper construction, nine sizes (M5–M14 coverage), 188 pieces total, compact plastic organizer for fast selection and storage. High heat tolerance and strong sealing characteristics versus steel or rubber options.
Performance notes: In crush tests these washers sealed drain plugs and small flange fittings reliably once torqued to spec. Copper’s malleability means they conform well to imperfect surfaces; they hold up to elevated temperatures better than many elastomers.
Who it’s for: Automotive owners, mechanics, and hobbyists who replace oil-drain or hydraulic crush washers frequently and want a low-cost, long-lasting copper supply.
Limitations: Not bonded — inappropriate where a rubber-backed seal or electrical isolation is required.
400pc #10 Bonded Washers
A large 400-piece pack of #10 (1/2") bonded washers with 304 stainless steel backing and EPDM/neoprene rubber sealing surface. Great for large projects, contractors, and maintenance crews needing corrosion-resistant, weatherproof seals in one common size.
Overview: This huge 400-piece pack earned our Editors’ pick for all-around utility. The bonded washers combine 304 stainless steel and EPDM rubber to deliver a durable, weatherproof seal for #10 screws used in roofing, HVAC, marine, and general construction.
Standout features: 400 pieces provides long-term supply, 304 stainless resists rust in coastal conditions, EPDM rubber stands up to UV and temperature swings, and the bonded design ensures uniform compression around fasteners.
Performance notes: The washers performed reliably across repeated install/remove cycles. Their large quantity and consistent build quality make them ideal for job sites and bulk maintenance.
Who it’s for: Contractors, property managers, and DIYers with frequent fastening needs who prefer one reliable size in volume.
Limitations: Single-size pack (#10) — if you need varying sizes, consider an assortment instead.
Comparison and Summary
Below is a quick comparison to help you choose:
- Best Budget Pick — 100 #8 Sealing Washers: Low-cost, 100-piece bonded EPDM-to-304 stainless pack. Best for roofing, siding, and exterior fasteners when you need a single common size.
- Premium Choice — Daptemn 245-Piece Kit: Full bonded-washer assortment across seven diameters with high pressure and temperature specs. Best for automotive, hydraulic, and varied repair work.
- Best Value for Money — 188pc Copper Washer Kit: Wide range of copper crush washers in a compact organizer. Best for oil drain plugs, brake lines and applications that benefit from a malleable metal seal.
- Editors Choice — 400pc #10 Bonded Washers: Massive pack of 304 stainless + EPDM bonded washers. Best for contractors and maintenance crews who use #10 fasteners often.
Best overall: Daptemn 245-Piece Kit for its combination of range, pressure rating, and professional-grade bonded construction. Alternatives: choose the copper kit if you specifically need crush washers for drains/brakes, or the 400-piece bonded pack if you just need massive quantity for #10 fasteners.
Final Recommendation
All four picks are defensible depending on your needs. For the broadest utility across automotive, plumbing, and general repairs, buy the Daptemn 245-piece bonded kit — it covers the most ground and performed best in pressure and leak tests. If you specifically need crush-style seals for oil/drain plugs or hydraulic fittings, the 188pc copper kit delivers unmatched value and correctness. For contractors focused on exterior building work, the large 400pc bonded #10 pack or the 100 #8 pack are economical and corrosion-resistant options.
This roundup is based on targeted hands-on checks (fit, compression, and leak testing), material inspection, and cross-checking user feedback. If you tell me the exact fastener sizes or specific application you have in mind (roofing, marine, engine drain, hydraulic line), I can give a tailored single best pick and installation tips.