Can I answer the question?
>>>Could it be another difference between regular home-style detergents (Sears Ultra Plus powder in my case) and commercial systems? Like, home-style detergents contain anti-redeposition agents that commercial systems don't have or need?>>>
See, I’ve been here for only a week or so, yet learned so much from Professor Sudsman. Let me take a stab at answering this question:
Here is an excerpt from a commercial detergent label: “Contains anti-redepositing agents, optical brighteners, builders, emulsifiers and wetting agents. Blended to provide optimum balance of alkalinity and detergency.”
Most detergents (store-bought and commercial) contain some common ingredients, including anti-redepositing agents. The commercial detergents (depending on the application for which they’re formulated) can also contain high amounts of alkaline builders, which expand the textile fibers, allowing soil to be more easily removed in the wash process. Commercial dry bleach can have between 9% and 18% available bleach content, while regular Clorox is around 5%. These, along with other factors, make the time necessary to “clean” the load much less than what you would need using supermarket brands. Overexposure to bleach can cause damage and greying. Thus, short wash/bleach bath cycles. Multiple rinses with commercial additives like anti-chlor and sour are necessary to neutralize the alkalinity and chlorine presence and bring the final pH back to normal, prolonging the life of the textile, not to mention, making it easier to handle during the finishing process.
But, being the student in training, I yield to the sudsman for correction and/or clarification.