Designation: D3050 − 07 (Reapproved 2015)

Standard Guide for

Measuring Soil Removal from Artificially Soiled Fabrics (Not
Suitable for Detergent Ranking)1
This standard is issued under the fixed designation D3050; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

1. Scope 4. Significance and Use

1.1 This is a guide for measuring the ability of detergents to 4.1 The guide, as now constituted, is not suitable for ranking
remove artificially applied soils from fabrics. It is intended as of detergent products since no basis is available at this time for
a laboratory screening test to aid in the formulation of correlation of the detergency performance of any particular
detergent products, for quality control and as a basis between soiled cloth or clothes with detergency of naturally soiled
the purchaser and seller in standardizing specific products’ articles.
performance. 4.2 A suggested procedure for comparing the performance
1.2 The relative ranking of detergent products will vary of any two laundry detergents on naturally soiled family items
greatly depending on the type of soiled fabrics used in the test. in home laundry equipment under controlled conditions on a
Therefore, selection of the standard soiled fabric to be used in paired comparison basis is described in Method D2960.
a test shall be made by agreement between the interested
parties on the basis of experience. 5. Apparatus
1.3 This standard does not purport to address all of the 5.1 Laboratory Washer—A laboratory scale agitator-type
safety concerns, if any, associated with its use. It is the washing machine.4
responsibility of the user of this standard to establish appro- 5.2 Reflectometer, calibrated by means of standard vitreous
priate safety and health practices and determine the applica- enamel plaques having reflectances in the range of the fabric or
bility of regulatory limitations prior to use. swatch samples being measured.

2. Referenced Documents 6. Reagents and Materials

2.1 ASTM Standards: 2 6.1 Purity of Reagents—Reagent grade chemicals shall be
D1193 Specification for Reagent Water used in all tests. Unless otherwise indicated, it is intended that
D2960 Guide for Controlled Laundering Test Using Natu- all reagents shall conform to the specifications of the Commit-
rally Soiled Fabrics and Household Appliances (With- tee on Analytical Reagents of the American Chemical Society,
drawn 2013)3 where such specifications are available.5 Other grades may be
used, provided it is first ascertained that the reagent is of
3. Summary of Guide sufficiently high purity to permit its use without lessening the
accuracy of the determination.
3.1 Soiled fabric swatches are washed in a laboratory
washer using the products being tested and the change in 6.2 Purity of Water—Unless otherwise indicated, references
reflectance is measured. to water shall be understood to mean Type IV reagent water
conforming to Specification D1193.
6.3 Hard Water Stock Solution—Prepare a hard water stock
1
This guide is under the jurisdiction of ASTM Committee D12 on Soaps and
solution by dissolving 2.940 6 0.002 g of calcium chloride
Other Detergents and is the responsibility of Subcommittee D12.15 on Physical dihydrate (CaCl2·2H2O) and 2.033 6 0.002 g of magnesium
Testing.
Current edition approved May 1, 2015. Published July 2015. Originally approved
4
in 1972. Last previous edition approved in 2007 as D3050 – 07. DOI: 10.1520/ The Terg-o-tometer, obtainable from the United States Testing Co., 1415 Park
D3050-07R15. Ave., Hoboken, NJ, or its equivalent, has been found satisfactory for this purpose.
2 5
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Reagent Chemicals, American Chemical Society Specifications , American
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Standards volume information, refer to the standard’s Document Summary page on listed by the American Chemical Society, see Analar Standards for Laboratory
the ASTM website. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
3
The last approved version of this historical standard is referenced on and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
www.astm.org. MD.

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1
 D3050 − 07 (2015)
chloride hexahydrate (MgCl2·6H2O) in about 300 mL of water. 8. Instrumental Evaluations and Calculations
Dilute to a volume of 1 L with additional water. This solution
8.1 Measure the reflectance, L, and both parameters “a” and
contains 3000 ppm hardness (expressed as calcium carbonate)
“b” of the residual soils relative to the unsoiled fabric with a
with a Ca:Mg molar ratio of 2:1. Other ratios may be used.
photoelectric colorimeter.
6.4 Reference Detergent—A comparison detergent suitable 8.1.1 Carefully present each swatch to the instrument with
to the fabric and conditions shall be included in each run. the same orientation, for example, long direction perpendicular
6.5 Standard Soiled Fabrics. to operator. Back each swatch with the other replicate speci-
NOTE 1—Most commercially available soiled swatches are based on mens (usually five) representing the same treatment variable.
particulate component such as clay, iron oxide, carbon black, vacuum 8.1.2 Read swatches with no ultraviolet light. Standard filter
cleaner dust, air-conditioner filter dust or other particulate, inorganic or for eliminating ultraviolet from light source should be used.
organic matter, with or without one or more oily components such as
synthetic sebum, oil, or grease. 8.2 Measure the reflectance of the unsoiled washed refer-
ence as described in 8.1.
7. Procedure
7.1 Operate the washer at a suitable fixed speed (90 cycles/ 8.3 Calculate the soil removal index (SRI) for each test
min is suggested). Maintain the water bath at a temperature specimen using the following formula:
suitable to the fabric, detergent, and conditions of the test. SRI 5 100 2 @ ~ L c 2 L w ! 2 1 ~ a c 2 a w ! 2 1 ~ b c 2 b w ! 2 # 1/2 (1)
Prepare duplicate solutions of the test product and the reference
where:
detergent in 1000 mL of water at the desired concentration,
temperature, and water hardness. It is recommended that L = reflectance (white/black),
concentrations of 0.1, 0.15, 0.2 and 0.25 %, temperature of 60, a = redness/greenness,
b = yellowness/blueness,
90, and 120°F (16, 35, and 49°C) and water hardnesses of 35,
c = unsoiled fabric, washed in the treatment conditions,
150, and 300 ppm be included. Transfer the solutions to the
and
buckets of the washer. Add to each bucket in rapid succession w = soiled fabric.
the selected soiled swatches and wash for 10 min. Then remove
the swatches, squeeze them by hand and transfer to a bucket 8.4 Improvement in Reflectance—Calculate the improve-
containing 1000 mL of water of the same hardness at the same ment in reflectance as follows:
temperature and rinse 3 min. Then damp dry the swatches % improvement in reflectance 5 @ ~ A 2 B ! / ~ C 0 2 B ! # 3 100 (2)
between clean toweling and air or tumble dry. Determine the
reflectances of the washed and dried swatches. Replicate the where:
above tests a sufficient number of times for statistical signifi- A = average reflectance of the soiled swatches after
cance. washing,
B = average reflectance of the soiled swatches before
NOTE 2—If only one test is to be made, water hardness of 150 ppm is
suggested since approximately 80 % of the families in the United States washing, and
have this level of hardness or below. It should also be noted that while C0 = average reflectance of the unsoiled swatches before
natural soils add hardness to the wash bath, artificial soils may not; washing.
therefore a hardness of 75 ppm may be more realistic for the lower NOTE 4—If unsoiled swatches of the type used to make the soiled
hardness level. fabrics are not available, calculate the improvement in reflectance as
NOTE 3—To avoid discoloration or change, or both, in the structure of follows:
the swatch surfaces do not use a photographic print dryer, hand iron, or
mangle to dry the swatches. Improvement in reflectance ~ ∆Rd! 5 A 2 B (3)

ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned
in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk
of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and
if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards
and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should
make your views known to the ASTM Committee on Standards, at the address shown below.

This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above
address or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website
(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222
Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/