Evaluating Stain Removal Performance in Home Laundering – ASTM D4265
By: Katherine Hatherley, Lab Technician, email
What Products: Liquid laundry detergent, powder laundry detergent, laundry soda, laundry soap, washing powder, stain remover, pre-wash treatment.
What Test: ASTM D4265 Standard Guide for Evaluating Stain Removal Performance in Home Laundering.
Why This Test: This test is used to determine a product’s cleaning efficiency by its ability to remove standard stains.
Results: The results may be used for claims substantiation and cleaning efficiency compared to other products
tested with the same standard under the same test conditions.
You may have seen a laundry detergent commercial where two identical shirts are splashed with mud, wine, or rubbed with grass stain. This is usually followed by a comparison of what each shirt looks like after a certain product’s cleaning versus its competitor, right? But what really goes on in laboratory testing of stain removal products? Are lab technicians throwing mud at shirts?
One of the standard methods recognized worldwide to measure the stain removal efficiency of a home laundering product is ASTM D4265 – Evaluating Stain Removal Performance in Home Laundering. It is a full-scale evaluation of performance with household washers and dryers, closely correlating to the consumer experience. The method prescribes the types of washing machines and drying equipment that may be used. Fabric stains are artificially applied to specified fabric types and allowed to set for the prescribed amount of time. After this period, these stain swatches are washed with the products being compared and the relative degree of removal of the stains is evaluated.
What types of stains are used? This is not an exhaustive list, but some typical stains include:
- Animal fat/red dye
- Motor oil
- Red wine
- Dessert (chocolate)
- Tomato sauce
- Baby food
How is the degree of stain removal evaluated? Averaged reflectance measurements of the fabric are taken using a colorimeter before the cloth is stained, after it is stained, and again after being treated with the product and washed. The performance of the product is evaluated instrumentally by a Stain Removal Index (SRI). The SRI is a scale from 0-100, with 0 meaning no stain removal, and 100 meaning complete stain removal. The SRI is calculated as:
SRI = 100 x ΔE*(US-UF) – ΔE*(WS-UF)
UF = Unwashed (unstained) fabric area
ΔE*(US-UF) = Delta-E color difference between the unwashed stain and the unwashed fabric
Δ E*(WS-UF) = Delta-E color difference between the washed stain and the unwashed fabric.
The value ΔE (absolute color difference) is calculated as:
ΔE* = √ΔL*2+ Δa*2+ Δb*2
a = redness/greenness
b = yellowness/blueness
ASTM D4265 is an excellent test for comparing products’ stain removal ability under the same conditions, useful for “formulation studies, quality control, and ingredient raw material qualification”. However, the method notes that “there is no single combination of stain and fabric that will predict the overall performance of a product or treatment method”. Different conditions in the consumer home will deliver different results.
If you have a laundry product you would like tested, or specific questions about this method, please contact us at Dell Tech.
Joe McCarthy, Senior Regulatory Affairs Specialist