Five Stubborn Stains in Laundry Shops and Step-by-Step Treatment Solutions

In laundry shops, rust stains, mildew stains, corrosion marks, scorch marks, and unclear stains have been troublesome challenges for the industry for a long time. As a professional brand in the industrial and commercial laundry equipment, Kingstar has long focused on research into commercial laundry processes. Kingstar uses the technological advantages of intelligent washing machines to provide full-process solutions: stain identification, scientific treatment, and equipment adaptability. It helps commercial laundry improve quality and efficiency.

Five Stubborn Stains
Causes and professional treatment methods are as follows.

● Rust Stains

They are mostly caused by iron oxidation. They are brownish patches attached to fabrics and are common in hotel linen. Oxalic acid, widely used in the industry, only achieves temporary reduction. It converts ferric ions (Fe³⁺) into light-colored ferrous ions (Fe²⁺). However, the reaction is reversible. When exposed to air, rust stains reappear.

- Professional Treatment

Special rust removers (EDTA-2Na and hydrofluoric acid) can completely chelate iron ions through acidic complexation. It can remove rust stains forever. When treating cotton and linen fabrics, people should wet the stains with water first to avoid fiber corrosion and yellowing caused by direct contact with strong acids.

● Mildew Stains

Mildew stains form from fungal growth in damp and poorly ventilated environments. They are irregular gray, black, or yellow patches with unpleasant odors. They degrade fibers and may even cause fabric damage in severe cases. Regular scrubbing can hardly remove them completely, and residual mold easily recurs.

- Professional Treatment

Using sodium hypochlorite bleaching for chlorine-resistant fabrics (cotton) can kill bacteria and remove odors. Chlorine bleaching is prohibited for protein fibers. (silk, wool, nylon...) Instead, people can use a mixture of ammonia water and alcohol for gentle brushing. Hydrogen peroxide or sodium hydrosulfite can be used to lighten stains on white fabrics.

● Corrosion Stains

They are mostly caused by splashing strong acids, such as battery fluid. The acid concentrates as water evaporates and corrodes fibers latently. There are no obvious visible abnormalities, but the fabric will tear once rubbed.

- Professional Treatment

Laundries should inform customers of the risks in advance, neutralize the acid with dilute ammonia water repeatedly, then wash with a neutral detergent to reduce the possibility of damage as much as possible.

● Scorch Stains

They form when fabrics contact high temperatures. In severe cases, fiber strength drops sharply, and holes easily appear.

- Professional Treatment

People gently brush mild scorch marks with a diluted solution of hydrogen peroxide and ammonia water before rinsing. For large-area scorch marks, people should soak and bleach with an aqueous sodium perborate solution to reduce damage.

● Unclear Stains

The stains bind deeply with fibers after light, oxidation, and microbial activity. They have high treatment risks.

- Professional Treatment

People should follow the principle of acid before alkali, water before solvent, and do step-by-step testing to prevent discoloration or damage to fabrics.

Kingstar Washer
Targeting the pain points of stubborn stains in commercial laundry, Kingstar washing machines are an ideal equipment carrier for professional treatment with precision craftsmanship, intelligent control, and material protection.

● 304 Stainless Steel

All water-contact parts are made of 304 stainless steel. The surface is smooth and corrosion-resistant. It does not rust or release impurities even after long-term use. This avoids new rust stains and yellowing during washing to ensure clean and safe linen.

● Intelligent Temperature Control and Customizable Programs

The Kingstar washer has a 7–12-inch HD touch control system with customization of over 70 washing programs. It precisely controls water temperature, rotation speed, duration, and chemical dosing. 

- Rust stain removal

Low-temperature, gentle washing

- Mildew stain removal

High-temperature disinfection parameters
Paired with an automatic dosing system for accurate chemical dispensing, it greatly improves treatment efficiency.

● Inner Drum and Variable Frequency Power

The inner drum is tilted back 3.5° to achieve multi-dimensional fabric flipping and agitation. With a variable-frequency motor that has an adjustable speed from 15 to 400G, it ensures water flow and mechanical force penetrate fibers to break down stubborn stains. Also, it avoids damage from strong friction. The diamond-patterned perforated inner drum increases the friction area and washing rate, and reduces snags and tears.

● Triple Shock Absorption and Stable Structure

The triple shock absorption system (double-layer springs + rubber damping + dynamic damping) has a 98% shock absorption rate. It can run stably without a special foundation. During extended soaking and reaction periods for stubborn stain treatment, the machine operates smoothly with low noise.

Q&A

Q1: Rust stains on clothes often recur. Is oxalic acid enough for stain removal?

A1: No. Oxalic acid only reduces iron ions without complete removal, so the stains recur. We recommend using chelating agents such as EDTA-2Na together with the low-temperature, gentle washing program of Kingstar washing machines for thorough rust removal. It also avoids secondary pollution from water quality.

Q2: Can regular bleach be used for mildew spots on silk and wool bathrobes?

A2: Chlorine bleach and other strong oxidizers should be avoided because they make fiber brittle and discolored. A mixture of ammonia water and alcohol should be used for gentle local brushing. Then, they should be washed at a low temperature in a Kingstar wet cleaning machine with the special wool program to ensure fabric safety.

Q3: How to avoid fabric damage when dealing with unclear stains?

A3: Laundries should follow the principle of local testing first, and then step-by-step treatment. They should start with water-based reagents before solvents, and use weak acids/alkalis before strong agents.