Barbed Wire: Materials, Characteristics, and Selection for Play
Barbed wire manufacturing standards are defining in ASTM standards.
ASTM standards for American Society for Testing and Materials and “is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and services”ˢᵒᵘʳᶜᵉ
These standards define agreed upon industry characteristics for the manufacture of barbed wire. Barbed wire manufacturers are not obligated to manufacture their product according to theses standards but if you purchase products that claim to be complaint with these standards you know relatively speaking what to expect.
The primary ASTM standard we are concerned with is: A121-13 Standard Specification for Metallic-Coated Carbon Steel Barbed Wire.
Other standards potentially of interest are:
A641/A641M Specification for Zinc-Coated (Galvanized) Carbon Steel Wire
A856/A856M Specification for Zinc-5% Aluminum-Mischmetal Alloy-Coated Carbon Steel Wire
Coating Types and Classes
Coating Type: Refers to the material that the un-coated wire is coated with
Coating Class: Refers to the “weight”, amount, or thickness of the coating on the wire.
Coating Type A - Aluminum coated. This is very rarely used anymore.
Coating Type Z - Zinc-coated. Known as Galvanized. This is the most common. Coating Thickness: Class 3 > Class 1
Coating Type ZA - Relatively new. Zinc-5% Aluminum-Mischmetal. This is also known as Galfan wire. Coating Thickness: Class 3 > Class 60 > Class 1
Coating types available in the retail market that are not defined in the ASTM standards.
Synthetic Coated - Usually Galvanized or Galfan wire with an additional coating added of a synthetic substance typically vinyl, PVC, polyethylene (PE), or others.
Considerations for Galvanization
Barb Configurations
The ASTM standard sets the following standards for barb configuration:
Number of Barb Points: 2 or 4
Spacing of Barbs: 3” (76mm), 4” (102mm), or 5” (127mm)
Shape of Barbs: Half-round, Round, or Flat
The standard also specifies a barb must be at least 3/8” (9.5mm) in length, but sets no maximum length for a barb.
Top: Single-stranded wire
Bottom: Double-stranded wire
Pictured left: 2-point barb | Pictured right: 4-point barb
Wire Configurations
There are a few different characteristics of the wire specifically to consider.
Number of Strands: Single or Double
Twist Type (for Double Strand): Conventional (Traditional) or Reverse)
Materials: Carbon Steel or other
The ASTM standards don’t address number of strands, but the language is written in such a way that it assumes double stranded wire. The standards also don’t explicitly specify and twist type, only the direction the twists should be in and consistency thereof.
The ASTM standards are specifically written for carbon steel wire. Un-coated stainless steel barbed wire is available. It is a very niche, boutique product and as such is very expensive. It doesn’t have any practice commercial purposes and as such isn’t included in commercial or industrial standards.
#1 No Twist: Single strand
#2 Conventional (Traditional) Twist: Barbs are twisting onto a single strand and then the two strands are twisted together. The barb is effectively trapped by the twist of the wire.
#3 Reverse Twist: Barbs are twisted onto the strands
BEST PRACTICE
If you use Reverse Twist wire (with the barbs twisted outside of the line wires) the barbs can come loose. This can be a concern if you are crafting implements with barbs at the end of a length of wire. In this scenario, a barb could come off of your implement inadvertently.
To avoid this, leave a short length of the strands past the barb, untwist the strands and bend the individual strands back over the barb to prevent the barb from dislodging from the strands.
Wire Diameter and Length
The diameter (or thickness) of barbed wire is measured with the standard wire gauge.
Included is a chart of common barbed wire gauges.
Note: Barbed wire can be manufactured in half gauges (e.g. 12½, 14½, etc.)
Barbed wire is typically sold wound on metal or wooden spools.
The typical length of wire on a spool is 80-rod (1,320 feet)(1/4 of a mile)(~400 meters).
This is a lot of wire for our purposes.
A full spool of barbed wire, depending on wire characteristics, can weigh between 60 lbs (27 kg) and 80 lbs (26 kg).
Consider this when ordering it online, or if you plan to travel with it to events or parties.