Evaluate the benefits of using 'Vapor Degreasing' versus 'Aqueous Cleaning' for spiral retaining rings made of high-carbon steel before phosphate coating.

Vapor degreasing using chlorinated solvents (like Trichloroethylene, though regulated) is highly effective for removing heavy oils and lubricants from the tight coils of a spiral retaining ring due to its low surface tension and high solvency power. However, aqueous cleaning is becoming the industrial standard due to environmental regulations. For high-carbon steel (SAE 1070-1090), aqueous cleaning requires a robust drying stage and the addition of rust inhibitors to prevent 'flash rusting' before the phosphate coating (zinc or manganese) is applied. Phosphate coating provides a porous surface that improves oil retention for lubrication and adds a layer of corrosion protection, which is essential for rings used in automotive transmissions.