Understanding scrap metal grades can mean the difference between maximizing your recycling profits and leaving money on the table. Whether you’re a seasoned professional or just starting in metal recycling, the grading system determines everything from pricing to processing requirements. During my early days running quality control at a regional processing facility, I quickly learned that misidentifying a single grade could cost thousands in a shipment—a lesson that shaped my meticulous approach to metal classification.
The complexity of modern alloys and manufacturing processes has only increased the importance of accurate grading. Each grade tells a story about purity, contamination levels, and processing requirements that directly impact its market value and industrial applications.
What grades of scrap metal are there?
Scrap metal grades fall into two primary classifications: ferrous metals (containing iron) and non-ferrous metals (without iron), with each category subdivided into specific grades based on purity, contamination levels, and processing requirements. The Institute of Scrap Recycling Industries (ISRI) maintains the global standard specifications that provide a common language for buyers and sellers worldwide.
Primary classification system
The foundation of all scrap metal grading starts with the basic ferrous versus non-ferrous distinction. Ferrous metals represent the most commonly recycled materials, with the United States processing enough ferrous metal daily to build 25 Eiffel Towers every single day of the year. These iron-containing materials include everything from automotive bodies to structural steel, each requiring different processing approaches based on their specific grade.
Non-ferrous metals, while representing smaller volumes, typically command higher prices due to their specialized properties and processing requirements. Aluminum ranks as one of the most commonly recycled non-ferrous metals, found in everything from beverage cans to aircraft components.
Ferrous metal grades
Steel and iron scrap follow detailed ISRI specifications that consider thickness, size, and contamination levels. Heavy Melting Steel (HMS) represents the backbone of ferrous recycling, with HMS1 requiring pieces under 60 inches by 24 inches and at least 1/4 inch thick, while HMS2 allows thinner materials down to 1/8 inch thickness.
#1 Prepared steel must be over 1/4 inch thick and no longer than 5 feet by 3 feet wide, though some yards require 4 feet by 2 feet maximum dimensions. The preparation requirements exist because unprepared materials require additional processing time, equipment usage, and labor costs that reduce their value.
Shredded steel scrap (ISRI 210-211) consists of homogeneous iron and steel fragments magnetically separated from automobiles and other sources, with minimum density requirements of 70 pounds per cubic foot. Light iron, also called shred, includes appliances, desks, computer cases, and automobiles, all processed through shredding or baling before shipment to mills.
Cast iron receives separate classification due to its different properties and processing requirements. Cast iron breaks into two main categories in the United States, though other regions may use up to ten different classifications.
Copper grades and specifications
Copper grading represents one of the most nuanced aspects of scrap metal classification, with prices varying dramatically between grades. Bare bright copper commands the highest prices, reserved exclusively for bare, uncoated, unalloyed wire or cable with bright, shiny appearance. This premium grade excludes copper piping and requires complete removal of all insulation, solder, and coatings.
#1 copper wire consists of bare, uncoated, unalloyed copper wire scrap nodules, chopped or shredded, completely free of tin, lead, zinc, aluminum, iron, and any insulation or foreign contamination. #2 copper solids and tubing maintain 96% minimum copper content but allow some contamination like minimal solder, paint, or oil that doesn’t meet #1 grade requirements.
Light copper accommodates miscellaneous unalloyed copper scrap with 92% nominal copper content (88% minimum), including sheet copper, gutters, downspouts, and similar materials. This grade represents the third most valuable copper category, characterized by its somewhat dirty or blemished appearance from solder, paint, or coating residue.
Aluminum classification system
Aluminum grades reflect both alloy composition and contamination levels. Clean aluminum wire or cable must contain 99% aluminum content and remain free of hair wire, ACSR, wire screen, iron, insulation, and other non-metallic items. Recent ISRI updates include “tank aluminum chops and straws” requiring 99% aluminum content and “tease aluminum wire and cable” demanding 99.45% aluminum content.
Clean aluminum typically applies to aluminum cans or sheets free of contaminants, while painted aluminum includes materials with painted or coated surfaces. Dirty aluminum contains significant contamination from dirt, oil, or other metals, substantially reducing its value and processing options.
Aluminum wheels must be free of tires, dirt, and attachments like lead wheel weights. Aluminum extrusion dealer grade consists of old extruded aluminum of single alloys, typically 6063, 6061, or 7075, free of iron, thermal breaks, saw chips, zinc corners, dirt, paper, and cardboard.
Brass and bronze categories
Brass grading depends heavily on copper content and alloy composition. Yellow brass contains approximately 60-70% copper with 30-40% zinc, appearing more yellowish due to higher zinc content, while red brass contains higher copper percentages. Composition or red brass consists of red brass scrap, valves, machinery bearings, and castings made of copper, tin, zinc, and lead, but excludes semi-red brass castings and high-lead alloys.
Machinery or hard brass borings require minimum 75% copper content, 6% tin minimum, 6-11% lead content, and total impurities under 0.75% excluding zinc, antimony, and nickel. Lead-free bismuth brass solids consist of castings alloyed with copper, tin, bismuth, and zinc, containing less than 0.2% alloyed lead.
Specialty metal grades
Stainless steel grades focus on chromium and nickel content variations. Grade 201 stainless steel features low nickel content and higher nitrogen for increased yield strength, while Grade 301 represents austenitic chromium-nickel stainless steel that becomes magnetic when cold worked.
Nickel scrap requires minimum 98% nickel content with maximum 0.50% copper, remaining free of castings, soldered, brazed, or painted materials. Lead categories include soft lead free of contaminants, mixed hard/soft lead combinations, and lead wheel weights used for automotive wheel balancing.
Quality factors affecting grades
Several factors determine final grading: metal type serves as the primary influence, while purity levels, contamination presence, size and shape, and processing requirements all impact grade designation and resulting value. Contamination types include paint, oil, other metals, insulation, and foreign attachments that require removal or downgrade the material.
Size and shape limitations exist because smaller or oddly shaped pieces create processing challenges that increase costs and reduce efficiency. Processing requirements vary significantly between grades, with higher grades demanding minimal processing while lower grades require extensive cleaning, sorting, or preparation.
Geographic and market variations
While ISRI specifications provide global standards, regional variations exist in interpretation and pricing. Scrap metal prices vary dramatically by location, with Maine averaging $100-140 per ton for #1 prepared steel while New York and Pennsylvania approach $200-250 per ton for light iron. China’s strict new standards require 99.9% copper content for bare bright copper wire imports and varying aluminum content minimums from 91% to 100% depending on the specific grade.
Processing facilities often develop their own interpretations within ISRI guidelines, making advance communication essential for successful transactions. Understanding these regional differences prevents costly misunderstandings and ensures appropriate pricing expectations.
Grade certification and verification
ISRI maintains arbitration services for resolving grading disputes between buyers and sellers, emphasizing the importance of written agreements for any specification deviations. Professional verification becomes crucial for high-value loads where accurate grading directly impacts profitability.
Many facilities now employ advanced sorting technologies including spectral analysis and automated separation systems to ensure accurate grading. These tools reduce human error and provide consistent classification that meets strict buyer requirements.
Conclusion
Understanding scrap metal grades transforms recycling from guesswork into profitable precision. The last time I sorted a mixed copper load, applying these grading principles increased the overall value by 40% simply through proper separation and cleaning. Years of hands-on experience have taught me that grade knowledge represents the difference between surviving and thriving in metal recycling. Each properly identified grade means maximized returns, satisfied customers, and sustainable processing operations that benefit everyone in the recycling chain.