TSG Chapter V. Analysis and Testing Methods for Textiles - Section B. Spot Tests for Colorfastness

From Wiki

Textiles.gif Textile Specialty Group Conservation Wiki
Back to Chapter V. Analysis and Testing Materials for Textiles
Back to Textiles Chapter List

Contributors: Originally drafted by Susan Heald. Contributions from: Dorothy Stites Alig, Deborah Bede, Maryann Butterfield, Lucy Commoner, Linda Eaton, Martha Winslow Grimm, La Tasha Harris, Jane Hutchins, Mary Kaldany, Jane Merritt, Susan Mathisen, Meredith Montague, Denise K. Migdail, Zoe Annis Perkins, LoErna Simpson, Gwen Spicer, Deborah Trupin.
Editors: M. Cynthia Hughes, Sara J. Wolf. Final Revision, April 2, 1998.
Your name could be here! Please contribute.

Copyright: 2018. The Textile Wiki pages are a publication of the Textile Specialty Group of the American Institute for Conservation of Historic and Artistic Works.
The Textile Wiki pages are published for the members of the Textile Specialty Group. Publication does not endorse or recommend any treatments, methods, or techniques described herein.


Spot Tests for Colorfastness

Introduction and Purpose

Colorfastness: the resistance of a material to change in any of its color characteristics, to transfer of its colorant(s) to adjacent materials, or both, as a result of the exposure of the material to any environment that might be encountered during handling, storage, treatment or display of the material.

  • Textile artifacts are tested before cleaning in aqueous or organic solvent solutions to determine if any colorant will bleed into the solution or transfer to adjacent fibers or materials; all colored components, including backing and repair fabrics and yarns are tested to determine their potential for color loss or transfer.
  • Backing and repair fabrics are tested to determine the potential for dye transfer by contact and abrasion (see Crockmeter, below).

Factors to consider

All colored materials in an artifact should be tested individually.

  • warp and weft yarns (separately if different colors)
  • thread in seams or appliqué
  • old repairs
  • colored stains
  • facings, interfacings, linings and/or support materials
  • trim and/or surface embellishment (embroidery yarns, applied fabrics and other materials, paints, inks)


Finishes may impact on the test results or may be changed by spot testing techniques.

  • Finishes may mask dye bleeding temporarily
  • spot testing may destroy finish or cause spotting or darkening of finish medium.


Testing may require destroying or irreversibly changing a small amount of material.

  • Removing a small yarn sample from a discrete or damaged area.
  • Testing in situ in a unobtrusive area, such as an edge, or inside a seam allowance. If color is fugitive, testing directly on the fabric may leave a small area of color loss.
  • Test solution, even water alone, may cause staining or disruption of surface characteristics.


Transfer of dirt and soiling during testing with a solution may mask color transfer or cause spotting on clean areas.
Fabric type may be a consideration in the selection of testing materials, or may alter the standard order of testing.

[N.B. For silks and glazed fabrics, the standard order of testing - water, water and detergent, warm water and detergent - may be altered in certain instances depending on the particular fabric.]


If test results are negative, you have proven only that the area tested does not run in the amount of time of the test. Tests do not simulate the effects of immersion.

Dye bleeding may still unexpectedly occur during washing, soaking, rinsing, or during the drying period.


Materials and Equipment

Liquids to be used for testing

  • deionized or distilled water
  • surfactant solution to be used in wash bath at intended temperature
  • 2% acetic acid
  • 2% ammonia
  • organic solvents

Materials and tools to be used for testing

  • pipette, eye dropper, brush, swabs
  • unbuffered blotters, filter paper, diapers, 100% cotton fabric
  • weights (such as glass plates)
  • polyester (Mylar®) or polyethylene film
  • Crockmeter
  • bleached, desized cotton test cloth

Test Methods

Basic Test Method

  • Test first with the weakest solution. This is usually water at room temperature. A strong indication of unstable dyes at this stage may make further testing unnecessary. If, however, the results are negative, testing with progressively stronger or warmer solutions may be continued.
  • Wet out a small thread sample taken from the textile or wet a discrete area on the textile with one of the liquids to be used in the treatment.
  • Place the area between two pieces of blotter or filter paper (or cotton fabric). Cover with polyester or polyethylene film and place under weights. [N.B.: if paper or fabric is allowed to extend beyond the edges of the weights, the drying period is shortened due to capillary action.]
  • Allow moisture to evaporate completely, and then examine blotters or filter paper for evidence of dye transfer.

Variations on the Basic Test Method

  • water temperature can be warmer than that which will be used for cleaning
  • use stronger detergent solution than that which will be used for cleaning
  • repeat test 2 or 3 times with the same thread or in the same location
  • run test for the same amount of time as the anticipated cleaning process
  • run test on a different section of the textile

Alternate test method #1 (for wet cleaning) - using a thread sample removed from the textile artifact:

1.Divide a small thread sample into four pieces. Place each on a piece of filter paper, undyed fabric or cotton balls, in a plastic tray, and dampen the samples with the following solutions:
  • distilled or deionized water (depending on what will be used in the wash bath)
  • surfactant solution
  • 2% acetic acid
  • 2% ammonia [N.B. the acid (acetic acid) and base (ammonia) solutions may show if the dye is acid or basic, and provide information on the pH sensitivity of the dye.]
2. Cover the samples with polyethylene sheeting.
3. Check for color transfer immediately, after 1/2 hour, 1 hour, 2 hours, etc., until samples have dried.

Alternate test method #2:

1.Follow method described in Step 1. above.
2. Cover samples with a second piece of filter paper or blotter. Sandwich the blotters between pieces of Mylar® and place under a weight.
3. Check for color transfer after 10–15 minutes. Re-assemble the weighted package.
4. Check again for color transfer at 1/2 hour, 1 hour, 2 hours, etc., until the samples are dry.

Alternate test method #3 (for wet cleaning) - testing in situ:

1. Using the solutions described in Step 1. above, place filter paper above and below test area and sandwich the filter paper between glass weights (or between pieces of Mylar® and then weight).
2. Observe for color transfer as above.

Testing in situ - special considerations.

  • After testing with surfactants, acids and bases, area should be flushed by applying water, or blotting with absorbent material to keep from leaving residue or an area with extreme pH.
  • Printed textiles. Place blotter beneath spot to be tested and wet textile with a swab until water (water + detergent) penetrates. Press dampened area with a second piece of blotter and check for color transfer. Replace blotter, cover with Mylar® and weight Check for color transfer as above.
  • Woven fabrics with floats on the back. Isolate float threads on the back by inserting a piece of Mylar® between the float threads and the textiles. Test as for alternate test method #3, above. [N.B.: not appropriate for woven silk with dense floats of unspun threads on the back which could be pulled during insertion or removal of the Mylar®]
  • Pile Rugs and Carpets. Check the base of the knots for color changes or for dye transfer which may indicate unstable dyes and previous wetting. Check also for areas and knots that may have been painted instead of reknotted.
  • Painted textiles. Test for sensitive paint by gently rolling a swab dampened with water (or solvent, or detergent solution) over the surface of the paint. Check the swab for transfer of pigment, and examine surface of paint for color or surface change.

Crockmeter test method

The Crockmeter test method for backing and repair fabrics (based upon American Association of Textile Chemists and Colorists (AATCC) Test Method 8, Colorfastness to Crocking. This test uses the AATCC Crockmeter to control the weight and pressure of the contact (rubbing finger) and the amount of time (cycles) the fabrics are in contact rubbing each other. [N.B. Any improvising to adapt this Crockmeter method with simpler equipment should consistently control the variables of weight and pressure of contact/rubbing time and the length of contact time (number of cycles).]

1. Cut two specimens of the backing/repair fabric to be tested for colorfastness, each 2" x 5", cut on the bias so that both warp and filling yarns contribute equally to the color transfer testing.
2. Mount one specimen on the bottom platform, placing the specimen holder over the fabric.
3. Mount a 2" x 2" square piece of white, desized and bleached, combed cotton test cloth on the crockmeter peg/finger, using the special clip to hold it in place.
4. Lower the covered finger onto the test specimen. Crank the meter handle 10 complete turns, at the rate of one turn per second, to slide the covered finger back and forth 20 times.
5. Lift the finger, remove the white test cloth and evaluate the degree of color transferred from the backing fabric onto the white surface.
6. Wet out a second 2" x 2" square of the cotton test cloth, blotting on absorbent paper to remove excess water. Replace the backing fabric specimen on the platform with the second cut specimen.
7. Proceed with the test in the same manner as Steps 4 - 6, above, using the wetted out cotton test cloth, making sure the finger does not rest on the backing fabric any longer than needed to complete the 10 complete cycles. Usually, fabrics will show more color transference under wet conditions than when dry.


References

American Association of Textile Chemists and Colorists.1988. "AATCC Test Method 8–1988, Colorfastness to Crocking: AATCC Crockmeter Method." AATCC Technical Manual. Research Triangle Park, NC: AATCC .

Further Reading

Dalby, Gill. 1985.Natural Dyes, Fast or Fugitive. Somerset, England: Mayhill Publications.10–11.
Flury-Lemberg, Mechthild. 1988.Textile Conservation and Research. Bern: Abegg-Stiftung. 24.
Landi, Sheila. 1992. The Textile Conservator's Manual. 2nd edition, London: Butterworths. 50–51.
Trotman, E.R. 1984. "Testing Dyed Materials" in Dyeing and Chemical Technology of Textile Fibers. 6th ed. High Wycombe: Charles Griffin and Co., Ltd.517–520.



Specialized Equipment/Materials Suppliers

  • AATCC Crockmeter (manual or motorized) - Atlas Electric Devices Co., 4114 North Ravenswood Ave., Chicago, IL 60613.
  • White, desized and bleached, combed cotton test cloth - Testfabrics Inc., PO Box 420, Middlesex, NJ 08846.



Back to Chapter V. Analysis and Testing Materials for Textiles
Back to Textiles Chapter List