The easiest way for a factory to cut cost is to change the material: a cheaper grade, a look-alike metal, a thinner sheet. Pick your material to see the usual swaps, how to catch each one, and the exact words to put in your specification so it doesn’t happen.
bottles, cookware, cutlery, sinks, fittings
Stainless steel
The swap
Grade 201 (about 3.5–5.5% nickel and 5.5–7.5% manganese) or ferritic 430 (no nickel) sold as 304 (18% chromium, 8% nickel).
Why it happens
Nickel is expensive, so less of it cuts the cost. 201 resists corrosion less well than 304, especially against salt and acidic contents.
How to catch it
A magnet catches 430, which is strongly magnetic, but not 201: both 201 and 304 are austenitic, and 304 itself can turn slightly magnetic after bending or pressing. A magnet can’t prove 304.
A handheld XRF analyser reads the chromium, nickel and manganese in seconds. Ask your inspection company to bring one.
Ask for the mill certificate (EN 10204 type 3.1) for the steel batch, and a lab analysis if there’s a dispute.
Put this in your specification
All [parts] in stainless steel grade 304 (EN 1.4301 / UNS S30400). Mill certificate EN 10204 3.1 for each batch of material. The buyer may verify the grade by XRF analysis at inspection.
Die-cast zinc alloy (Zamak) plated to look like brass.
Why it happens
Zinc alloy is cheaper and easier to cast. It is weaker, and once the plating wears it corrodes differently.
How to catch it
Weigh it. Zamak 3 is about 6.6 g/cm³ and yellow brass about 8.5 g/cm³, so the same part in zinc alloy weighs roughly a fifth less than in brass. Compare with the golden sample.
On a hidden spot, a file or scratch shows grey metal under the plating; brass stays yellow all the way through.
An XRF analyser separates copper-based brass from zinc alloy instantly.
Put this in your specification
Body and [parts] in solid brass (state the alloy, e.g. CW617N), no zinc die-cast parts. Plating: [finish and thickness]. Unit weight [x] g ± [y] g.
power cords, extension leads, data cables, windings
Copper wire and cable
The swap
Copper-clad aluminium (CCA): an aluminium core with a thin copper coating, sold as copper.
Why it happens
Aluminium is far cheaper than copper. CCA is weaker, carries less current for its size and oxidises at connections. Standards for Cat 5e, 6 and 6a data cable require copper conductors.
How to catch it
Cut or scrape the end of a conductor: CCA shows a silver-grey aluminium core under the copper colour.
Weigh a measured length against a copper reference: aluminium is much lighter.
For mains cable, look for independent approval, such as BASEC in the UK, and ask the lab to check conductor resistance.
Put this in your specification
Conductors of plain annealed copper throughout; no copper-clad aluminium, steel or recycled-copper alloys. Cable to [standard], with a test report for conductor resistance.
Cheap alloys or plating containing lead, cadmium or nickel.
Why it happens
They’re cheap and easy to cast or plate, but UK law limits them because of the health risks.
How to catch it
UK limits: lead under 0.05% by weight in any part of jewellery; cadmium no more than 0.01% of the metal; nickel release no more than 0.5 µg per cm² a week for items in prolonged skin contact, and under 0.2 for piercing posts.
You can’t see these. Ask for a test report from an accredited laboratory for each batch; the supplier and you, as importer, are expected to have tested.
Put this in your specification
Complies with UK REACH Annex XVII limits for lead, cadmium and nickel release. Test report from an accredited laboratory for each production batch.
Polyester or a blend sold as 100% cotton, or less cotton than stated. Lighter fabric than agreed.
Why it happens
Synthetic fibre is cheaper, and a lighter fabric uses less of it. The fibre label is a legal requirement, and a wrong label is your problem as the seller.
How to catch it
A burn test at home is unreliable. A textile laboratory measures the fibre composition.
Weigh a cut square of fabric to check the weight per square metre (GSM) against the spec.
Put this in your specification
Fabric: 100% cotton [or exact blend], [x] g/m² ± 5%. Fibre composition test report from an accredited laboratory for each batch. Fibre label to UK textile labelling rules.
A cheaper plastic than agreed, recycled content where virgin material was specified, or a material not made for food contact.
Why it happens
Plastic is often the biggest material cost in a moulded product. For anything that touches food, the material has to meet food contact rules.
How to catch it
A testing laboratory can identify the type of plastic.
For food contact, get the declaration of compliance for the exact material and a migration test report.
Put this in your specification
Body in [material, e.g. polypropylene], food-contact grade, virgin material only unless agreed in writing. Declaration of compliance and migration test report for the final product.
Name the grade, not the material. “Stainless steel” lets a factory choose; “304 (EN 1.4301)” doesn’t.
Keep a golden sample and weigh against it. Weight is the cheapest test there is, and most swaps change it.
Test before the balance. Ask the inspection company for an XRF check, a weight check or a lab test, and make the balance payment depend on the result.
General guidance from a materials engineer, not a substitute for testing your product. For regulated products, use a UKAS-accredited laboratory: search the UKAS directory. If a price looks too good, run the price check too.
What are the most common material substitutions in Chinese manufacturing?
Cheaper grades of the same material (201 stainless steel for 304), cheaper materials made to look like better ones (plated zinc alloy for brass, copper-clad aluminium for copper), less material (thinner sheet, lighter fabric) and recycled or non-food-grade plastics. Each can be caught with a simple check if the specification is precise.
Can a magnet tell 304 stainless steel from 201?
No. Both are austenitic and non-magnetic when annealed, and 304 can become slightly magnetic after bending or pressing. A magnet does catch 430, which is ferritic. To confirm the grade, use an XRF analyser or a lab analysis.
How do I stop a factory changing the material?
Name the exact grade in the specification, ask for material certificates, keep a golden sample, and have the inspector weigh units and test the material before you pay the balance.
Want the material checked on your order?
I’m a materials engineer. I write the material into your specification, ask for the right certificates, and book an inspection that tests for the swaps before you pay the balance.
