Redeposition occurs in drycleaning when soils in the solvent resettle or redeposit on clothing instead of being carried off to the filters. Soil redeposition will be minimized if the filtered solvent flow rate is high enough to flush the soil rapidly from the washer and into the filter.
Redeposition can also result from improper classification of garments. Dark colored garments should not be cleaned with light colored garments for several reasons. Dark-colored garments may bleed in the load, allowing the dye to be absorbed by the lighter-colored garments. In addition, darker-colored garments are usually worn for a longer period of time since they do not readily show soils. The soils that are released in the cleaning cycle may be absorbed by the lighter colored garments.
Garments that are pre-spotted should be allowed to dry completely before re-cleaning to prevent localized redeposition. Cellulose fabrics are more prone to this type of staining, although it can occur on other types of fabrics.
Even though there are several other factors that can contribute to redeposition in the drycleaning machine, proper flow rates and the thorough drying of fabrics after stain removal are a few of the ways to prevent it.
DLI's Encyclopedia of Drycleaning Online features thousands of garments about all things drycleaning and is included as part of Standard, Gold, Premier or International memberships. Here are some bulletins to help further your understanding of this issue:
- Shirt Laundry Procedures (SLP) No. 132: How White are Your Shirts?
- Technical Operating Information (TOI) No. 667: Greying of Fabrics in Drycleaning
- Technical Operating Information (TOI) No. 744: Importance of Adequate Solvent Levels in the Drycleaning Machine