What 'clean' actually means at the yard, metal by metal

Every yard sorts scrap on two questions: what metal is it, and how much work does it need before it can go in a furnace? “Clean” is the yard’s answer to the second question. It has nothing to do with washing or polishing: a clean item is one metal, with nothing attached that the furnace doesn’t want. Where that line sits changes from metal to metal, and it decides the grade on your receipt.

Copper

Clean copper is unalloyed, uncoated and unattached. Solder is the classic contaminant: a single sweated joint moves a length of pipe from #1 Copper to #2 Copper. Brass valves, steel clips, paint and tinned (silver-coloured) wire do the same job. Anything still wrapped in plastic is Insulated Copper Wire, and Bare Bright Copper only applies to stripped, unoxidised wire and bar.

Home tests: copper is non-magnetic, so a magnet grabbing part of a piece means a steel fitting is still on it. A dull grey band at a fitting is solder. A silvery skin on wire is tinning, not bare bright.

Worth removing: brass fittings (cut them off and sell them as brass), steel screws and clips, and insulation on thick cable. If a soldered joint sits mid-pipe, cut a few centimetres either side of it so the rest grades as #1.

Not worth it: scrubbing tarnish, or trying to heat solder off short offcuts.

Aluminium

The top grade, Aluminium Extrusion, means bare, uncoated profile with nothing attached. Window and door frames arrive with steel screws, hinges, rollers, rubber seals, glass and plastic thermal breaks, all of which are contaminants, and paint or powder coat knocks frames out of the clean grade. Cast Aluminium brings steel studs, bearings, cylinder liners and oil. Aluminium Sheet loses grade to rivets and steel framing; Aluminium Cans (UBC) sit lowest because of their coatings.

Home tests: aluminium is non-magnetic and light. Run a magnet along the whole length of a frame to find steel rollers and screws you can’t see. If an item feels heavy for its size, it’s probably not aluminium.

Worth removing: steel screws, hinges and rollers (a cordless driver and a few minutes), glass, and rubber seals. Drain oil from castings.

Not worth it: stripping paint or powder coat, or grinding steel liners out of a block. Accept the lower grade.

Brass

Clean Yellow Brass or Red Brass is solid alloy with nothing else on it. Taps and bathroom fittings are the trap: chrome plating, steel spindles and springs, ceramic cartridges, rubber washers and plastic handles are standard. Soldered or brazed fittings and tap bodies with steel screws go to Plumbing Brass, and chrome-plated brass is graded down because the plating has to be dealt with in the melt.

Home tests: brass is non-magnetic, so a magnet pulling at a tap stem means a steel spindle or spring is inside. File a hidden spot on a plated item: yellow underneath means brass, grey means zinc die-cast or steel. Brass is also noticeably heavier than die-cast “brass-look” hardware.

Worth removing: steel screws and spindles, ceramic cartridges, plastic and rubber. Keep red brass separate from yellow if you can tell them apart.

Not worth it: trying to strip chrome plating.

Steel

Clean steel is a low bar, because shears and shredders can deal with a lot. What yards object to is non-ferrous metal, concrete, timber, rubber, sealed containers and oil. Galvanised steel is counted as steel, not zinc; the coating is too thin to matter. The other thing that matters is thickness: Heavy Melting Steel (HMS) needs to be 6mm or more, and anything thinner is Light Steel. A mixed pile is graded as the lighter, so keep beams and plate apart from appliance cabinets.

Home tests: the magnet is definitive, and it sticks firmly. Check a hot water cylinder before it goes on the steel pile; some older ones are copper and worth far more. Yards use a grinder spark test to separate carbon steel from stainless, but it throws hot sparks and grit and is not a sensible home test; the magnet does most of the same work.

Worth removing: copper motor windings, brass and copper fittings from cylinders and appliances, aluminium and lead. All pay more sold separately, and all drag a steel load down.

Not worth it: paint, rust, galvanising, or small plastic knobs and grommets.

Stainless steel

Clean 304 Stainless or 316 Stainless is one grade of stainless with no carbon steel, brass, aluminium or plastic attached. Sinks come with steel brackets and clips, brass or chrome-plated wastes and rubber gaskets. Cookware often hides an aluminium or copper disc in the base, which makes it mixed.

Home tests: the magnet is the key test, and it works backwards here. Good 304 and 316 are mostly non-magnetic, so a magnet should slide off or barely grab. If it sticks firmly, the item is usually plain steel or a lower-value magnetic stainless, and will be paid as such. One caveat: heavily worked 304, such as the pressed corners of a sink, can pull a magnet weakly at the edges without being a lesser grade. No home test tells 304 from 316; unless the item came with documentation or from marine or chemical service, assume 304.

Worth removing: brackets, clips, taps and waste fittings.

Not worth it: polishing, or trying to separate a sandwich-base saucepan.

Lead

Soft Lead means pipe, sheet, flashing and weights with nothing on them. Common contaminants are steel clips on wheel weights, brass fittings on old pipe, mortar or bitumen on roof flashing, and the steel bolts on battery terminal clamps. Lead-Acid Batteries are a separate grade, priced whole, and should stay whole and upright. Many newer wheel weights are steel or zinc, not lead.

Home tests: weight and softness. A fist-sized piece of lead is surprisingly heavy, bends easily, and scratches with a fingernail, leaving a grey streak on paper. Steel weights stick to a magnet; zinc ones are lighter and harder.

Worth removing: steel clips and bolts, brass fittings, and any non-lead weights mixed in.

Not worth it: cutting or grinding lead of any kind. Wash your hands after handling it.

Zinc

Clean Zinc is die-cast hardware, sheet zinc or boat anodes with no steel, plating or plastic. Die-cast is nearly always plated or painted and turns up with steel screws, springs and inserts; anodes carry a steel core. Galvanised sheet and pipe are steel, not zinc, no matter how much coating is on them.

Home tests: zinc is non-magnetic, sits between aluminium and brass for weight, scratches easily to a bright grey, and die-cast snaps rather than bends.

Worth removing: steel screws, springs, rubber and plastic.

Not worth it: plating or paint.

Nickel

Clean Nickel means pure nickel anodes or sheet, and it is rare in household scrap. Nickel-plated taps and hardware are not nickel; the plating is microns thick, and the item is graded on the base metal. Cutlery marked “nickel silver” or EPNS is a copper alloy, not nickel scrap.

Home tests: nickel is one of the few metals besides steel that a magnet sticks to, so the magnet cannot separate it from steel or magnetic stainless. Most yards confirm nickel with a handheld analyser, and a nickel price should not be expected on a claim alone.

Worth removing: any steel fixings, if you are confident the base metal is nickel.

Not worth it: trying to recover plating.

Mixed loads, and why one dirty item costs you

A yard grades a bag by what has to be done to it, not by its best piece. If a bag of Bare Bright Copper has a few soldered offcuts in the bottom, either the whole bag is graded as #2 or the yard sorts it and recovers the time from your price. One aluminium frame full of steel rollers does the same to a pile of clean extrusion. Contaminants also add weight the yard will not pay for, so the deduction comes off the scale as well as the grade.

The practical rules follow from that. One metal per container. Keep grades apart within a metal. Put anything you are unsure about in its own bag and ask at the counter rather than burying it in a good load. Then run the sorted weights through the calculator to see what the clean grades should be worth before you go.