What Are Copper Cup Washers?
Copper cup washers (also known as copper finishing washers or copper countersunk washers) are precision-formed washers with a cup or countersunk profile, manufactured from pure copper or copper alloy. Unlike brass cup washers, copper finishing washers are chosen for their distinctive warm reddish-gold appearance, superior electrical conductivity, and excellent corrosion resistance in atmospheric and marine environments. Jamnagar Brass Components produces copper cup washers in ETP copper and OF copper for US architectural, marine, roofing, and electrical applications.
Types of Copper Cup Washers We Manufacture
ETP Copper Countersunk Cup Washers
Manufactured from Electrolytic Tough Pitch (ETP) copper (UNS C11000 / IS 191 Grade E), these are our standard copper finishing washers with 82° countersink for US flat-head screws (#4 to #14). Popular with US roofing contractors, timber frame builders, and architectural metalworkers.
Oxygen-Free Copper (OFC) Cup Washers
Made from UNS C10200 oxygen-free copper, these premium washers are used in applications requiring the highest purity copper — solar energy grounding, high-voltage electrical assemblies, and sensitive electronic enclosures.
Copper Oval Head Finishing Washers
Designed for raised oval-head (slotted or Phillips) screws, providing an elegantly domed appearance. Favored in Arts & Crafts furniture restoration, timber cladding, and period architectural projects in the USA.
Heavy-Duty Copper Cup Washers
Thicker gauge (0.062″ – 0.093″) cup washers for applications requiring greater load-bearing capacity, such as structural timber connections, post bases, and heavy outdoor furniture.
Roofing Copper Cup Washers
Extra-large OD copper finishing washers designed for use with roofing screws and roofing nails on copper sheet metal roofing, copper gutters, and copper flashing systems. OD up to 1″ (25mm) to maximize load distribution and weather sealing.
Material Grades and International Equivalents
| Copper Grade | India (IS) | USA (ASTM/UNS) | UK (BS) | Germany (DIN) | Key Property |
|---|---|---|---|---|---|
| ETP Copper | IS 191 Grade E | UNS C11000 / ASTM B152 | BS 2875 C101 | DIN CuETP | 100% IACS conductivity, standard grade |
| Oxygen-Free Copper | IS 191 Grade OF | UNS C10200 / ASTM B152 | BS C103 | DIN CuOF | 99.99% Cu, weld/braze quality |
| DHP Copper | IS 191 Grade DHP | UNS C12200 / ASTM B152 | BS C106 | DIN CuDHP | Deoxidized, plumbing/HVAC |
| Silicon Bronze | — | UNS C65500 / ASTM B99 | BS CS101 | DIN CuSi3Mn1 | Marine, high corrosion resistance |
Specifications and Sizes
- Screw Sizes: #4, #6, #8, #10, #12, #14 (US Imperial) and M3–M10 (Metric)
- Countersink Angle: 82° US standard; 90° metric standard
- OD Range: 0.375″ to 1.25″ (9.5mm to 32mm)
- Thickness: 0.028″ to 0.093″ (0.7mm to 2.4mm)
- Temper: Annealed (soft) for stamping; 1/4 hard for structural applications
- Finish: Natural copper, patinated (verde), lacquered, wax coated
Applications of Copper Cup Washers
- Copper Roofing & Cladding – Securing copper sheet, flashing, and guttering
- Timber Frame & Log Home Construction – Decorative screw finishing in exposed timber joinery
- Marine & Boat Building – Deck fittings, teak decking, hull fittings
- Architectural Metalwork – Decorative facades, canopies, signage
- Electrical Grounding – Connection points on copper grounding conductors
- Arts & Crafts / Period Restoration – Antique reproductions, period hardware
Why Choose Jamnagar Brass Components for Copper Cup Washers?
- Pure Copper Material – Material test certificates confirming copper purity and grade with every consignment.
- Consistent Stamping Quality – Burr-free edges, uniform countersink depth, and consistent thickness across production batches.
- Architectural Quality Finishes – Natural copper, lacquered, and patinated finishes for premium architectural and marine applications.
- US Market Screw Size Program – Full range of imperial screw sizes (82° countersink) stocked for US customers.
- Competitive Export Pricing – Factory-direct pricing significantly below US-sourced copper hardware.
- Flexible Quantities – Small trial orders and full container loads both welcome.
Frequently Asked Questions (FAQ)
Q: Will copper cup washers tarnish over time?
A: Yes, copper naturally develops a patina (oxidized layer) over time that ranges from dark brown to green (verdigris). This is aesthetically prized in architectural applications. For applications where a bright copper finish must be maintained, specify our lacquered copper cup washers.
Q: Are copper cup washers compatible with stainless steel screws?
A: Yes, copper and stainless steel can be used together in most environments with minimal galvanic corrosion risk. In highly saline or marine environments, consult our technical team for the appropriate combination.
Q: Can you produce copper cup washers to match a specific historic hardware profile?
A: Yes. Provide us with a sample or detailed drawing and we can produce matching tooling for period-accurate restoration hardware. Minimum quantities apply for custom tooling.
Q: What is the minimum order for copper cup washers?
A: For standard stock sizes, MOQ is 1,000 pieces. For custom sizes or special finishes, MOQ is 5,000 pieces. Mixed-size orders are welcome.
Request Copper Cup Washer Samples or Quotation
For pricing and samples on copper cup washers, contact Jamnagar Brass Components — your trusted copper hardware manufacturer from Jamnagar, India.
📧 Email: sales@jambrass.com
🌐 Website: www.jambrass.com