What is the M2 Test Solution for Stainless Steel Insulated Cups? – Composition and Principles

Every cup has a story, and life has its warmth. Hello everyone, and welcome to "Dong Dong's Cup Talk" In previous discussions, I’ve mentioned simple methods to test whether your stainless steel cup is made of 304 stainless steel, including the use of testing solutions. However, I haven’t yet provided a detailed explanation. https://www.zhanyict.com/en/ProductsDetail-VB-10525.htmlRecently, I’ve received messages from followers asking about the reagent testing process. Today, I’ll dive deeper into this topic. Given the amount of information, I’ll break it down into several parts for clarity.

I. Composition and Principles of the M2 Test Solution

1. Chemical Composition of M2

The M2 stainless steel testing solution primarily contains copper sulfate + acidic corrosive agents (such as dilute nitric acid). https://www.zhanyict.com/en/ProductsDetail-VB-10525.htmlIt identifies the nickel (Ni) content in metals through an electrochemical reaction. Due to its high nickel content (8–10%), 304 stainless steel produces a specific color reaction when tested.

2. Why a Battery Is Used for the Test

- The battery provides a stable electric current, accelerating the electrolytic reaction.

- A galvanic cell effect is formed on the stainless steel surface: https://www.zhanyict.com/en/ProductsDetail-VB-10525.htmlthe testing solution acts as the electrolyte, and the metal serves as the electrode.

- Without a battery, the reaction proceeds slowly, and the color change is less noticeable.

3. Cause of the Red-Brown Color

When 304 stainless steel comes into contact with the M2 solution:

High nickel content → Nickel ions are released →https://www.zhanyict.com/en/ProductsDetail-VB-10525.htmlReact with the solution to form nickel oxide → Red-brown precipitate