Polymers have become a widespread part of laundry detergent formulations because of their benefits which are usually delivered via surface modification of fibers. Therefore, there is a growing interest in understanding their deposition on fabrics. In this work, we have used streaming potential to assess changes in surface charge of polyester and knitted cotton after modification via soil release polymers (SRPs). Results identify a relationship between the measured zeta potential for the modified fabrics and the charge of the polymer. The effects of parameters, such as agitation speed and bulk concentration during deposition, have been investigated. Streaming potential data were then correlated to adsorption isotherms from UV absorbance data, and a Langmuir-Freundlich model was proposed to describe the isotherms for polyester. The stain removal index for some common hydrophobic stains was determined via image analysis. A link between SRP deposition efficiency and their effectiveness on greasy soil removal was observed.