What is Black Iron Wire?
Black iron wire — also called soft annealed wire or locally known as "itim na alambre" — is an uncoated steel wire that has been annealed (heat-treated) to make it soft, pliable, and easy to work with by hand. Unlike GI wire, which has a zinc coating applied for corrosion resistance, black iron wire is bare steel. This gives it a slightly darker, matte appearance and a naturally lower price point.
The annealing process is what makes black iron wire so practical for construction work. The heat treatment removes the internal stress from the wire, leaving it soft enough to bend, twist, and wrap tightly around rebar and other materials with minimal effort — no tools required. A worker can loop it around a rebar intersection and twist it securely using just their fingers or a simple wire-twisting tool in seconds.
It is worth comparing black iron wire to its galvanized counterpart. GI wire has a zinc coating that provides significant protection against rust and is better suited to applications where the wire will be exposed to moisture, humidity, or outdoor conditions over time. Black iron wire, by contrast, is best used in applications where corrosion resistance is not the primary concern — most commonly in concrete construction, where the wire is permanently encased in the pour and shielded from the elements once the structure is complete.
Black Iron Wire Specifications
We supply soft annealed black iron wire in standard construction gauges. Roll weights may vary by gauge; contact us to confirm current stock and pricing.
| Gauge | Wire Diameter (mm) | Tensile Strength | Roll Weight | Best For |
|---|---|---|---|---|
| #8 | 4.06 mm | ~380–450 MPa | ~35 kg | Heavy binding, securing large structural members, baling |
| #10 | 3.25 mm | ~380–450 MPa | ~35 kg | Rebar tying in heavy concrete work, bundling pipe and lumber |
| #12 | 2.64 mm | ~380–450 MPa | ~35 kg | Standard rebar tying in slabs and columns — most common gauge |
| #14 | 2.03 mm | ~380–430 MPa | ~35 kg | Light construction binding, chicken wire attachment, general use |
| #16 | 1.63 mm | ~380–430 MPa | ~35 kg | Fine tying, scaffolding wire ties, light packaging |
| #18 | 1.22 mm | ~350–420 MPa | ~30 kg | Delicate binding, crafts, trellises, light-duty fastening |
Other gauges available on request. Contact us with your gauge, quantity, and delivery requirements for a custom quote.
Common Uses in the Philippines
Black iron wire is a staple on Philippine construction sites for its combination of softness, low cost, and ease of use. Here are the most common applications:
- Concrete rebar tying. The primary use of black iron wire in the Philippines. Workers bind intersecting rebar with short lengths of #12 or #14 wire at every grid intersection before the concrete is poured. Because the wire will be permanently embedded in the slab or column, rust resistance is a secondary concern — softness and workability are what matter.
- Baling and bundling. Black iron wire is widely used to bundle rebar, pipes, timber, and other long materials for transport and on-site storage. The soft annealed quality means it wraps tightly and holds securely without springing back.
- General construction binding. From tying temporary form boards to securing tarps and safety nets on scaffolding, B.I. wire is the all-purpose fastener of the Philippine construction site. A roll on the tool belt is as essential as a hammer.
- DIY and fabrication work. Welders, metal fabricators, and home builders use black iron wire to hold parts in position during fitting and tacking, to bundle cut material, and for general workshop binding where a quick, strong, reusable fastener is needed.
- Tie wire for scaffolding. Scaffolding components — cross-braces, ledgers, putlogs — are often lashed together or secured with black iron wire on traditional bamboo and tube scaffolding setups common in Philippine construction.
Black Iron Wire vs. GI Wire — Which Should You Choose?
Both products serve as tie wire and binding wire, but each has a distinct advantage depending on your application. Use this comparison to choose the right one:
| Feature | Black Iron Wire | GI Wire |
|---|---|---|
| Price | Lower — uncoated wire costs less to produce | Slightly higher — zinc coating adds material and process cost |
| Rust Resistance | Low — bare steel will oxidize when exposed to moisture | High — zinc coating provides a barrier against rust and corrosion |
| Flexibility | Excellent — annealing makes it very soft and easy to work by hand | Good — galvanized wire is also soft but can be slightly stiffer |
| Best Environment | Indoors or in concrete — where exposure to moisture is minimal | Outdoors or exposed — wherever long-term weather resistance is needed |
| Common Application | Rebar tying in slabs, columns, and beams before concrete pour | Agricultural trellises, packaging, exposed fencing, outdoor binding |
Not sure which wire is right for your project? Call us at (02) 8260-0181 and we'll advise based on your specific requirements.
Why Buy Black Iron Wire from Una Wire?
- Manufacturer-direct pricing. We manufacture wire products at our Quezon City plant — there is no middleman markup. You pay factory prices whether you are buying a single roll or a full truckload.
- Consistent gauge accuracy. Every roll we produce is drawn to tight dimensional tolerances. The gauge you order is the gauge you receive — critical when your project specs call for a specific wire diameter for structural tying work.
- Available in bulk and retail quantities. Whether you need a single roll for a small project or a hundred rolls for a major construction contract, we accommodate both. Large orders can be discussed with our sales team for volume pricing and scheduled delivery.
How to Order
Ordering black iron wire from Una Wire is simple. Here are the three steps:
- Call us or submit the quote form. Reach us at (02) 8260-0181 or use the contact form on this page. Let us know the gauge(s) you need and the quantity.
- Confirm gauge and roll weight. We will confirm pricing, available stock, and lead time based on your requirements. Large or custom orders can be discussed for scheduling.
- Arrange delivery or Quezon City pickup. We deliver to Metro Manila and nearby provinces, or you can pick up directly from our factory in Balingasa, Quezon City at a time that suits your project schedule.
Or call us directly: (02) 8260-0181 · +63 922 857 7288