Step 1: Understanding the Question:
The question asks for the appropriate chemical treatment to fix white cotton garments that have taken on a blue tint because too much bluing agent was added during the wash.
Step 2: Detailed Explanation:
"Bluing" is a laundering practice where a trace amount of blue dye (like Prussian blue or ultramarine) is added to white fabrics. Because blue and yellow are complementary colors, the blue dye neutralizes the natural yellowing of aging cotton, tricking the eye into seeing a stark, bright white.
However, if an excessive amount of bluing agent is used, or if it isn't mixed properly, it causes "over-bluing"—leaving distinct blue streaks or an overall bluish tint on the fabric.
Most commercial bluing agents are slightly alkaline or are sensitive to acidic environments. To safely strip this excess dye out of cotton fibers without employing harsh, damaging bleaches, the fabric is rinsed in a dilute acid solution. Mild household acids like white vinegar (dilute acetic acid) are highly effective at breaking down and neutralizing the blue pigment, restoring the fabric's white appearance.
Step 3: Final Answer:
A dilute acid solution is used to rectify over-bluing in white cotton fabrics.