Disgusting-looking stuff that gets on people’s clothing falls into one of three categories: Insoluble soils, water-soluble soils and solvent-soluble soils. If a substance is soluble, it means it will break up and become part of the liquid; if it is insoluble, it won’t. Water-soluble soils come out in water-based processes, and solvent-soluble soils come out in dry (no-water) processes.
Insoluble soils include carbon and plain ol’ dirt. Water-soluble soils include anything that gets on a garment with water as its carrier, such as soda, coffee, tea, perspiration and many food stains. Solvent-soluble soils include oils and greases, and foods containing oils or greases. There are also “combination” stains that contain both water- and solvent-soluble soils.
Neither water nor solvents have much effect in removing insoluble soils. These soils must be removed mechanically—through shaking, vacuuming or other agitation. They can also be removed by applying a lubricant, agitating them with a bone scraper and flushing them with a wet or dry solvent.
Water-soluble stains must be removed with a spotting agent that contains water as its base. Some water- based stains will flush out with water alone, such as clear, sweet liquids. Other stains, however, require a stain-removal agent with additional ingredients. Solvent-soluble stains are rarely removed without solvent unless they are fresh, clear oils in small quantities.
Special Agents. The most useful ingredient in any spotting agent is a lubricating and penetrating agent, whether intended for water- or solvent-soluble soils. For insoluble soils such as carbon or topsoil, lubrication and agitation are necessary to help dislodge small chunks of staining matter. As the soil is dislodged, it can be absorbed into a clean towel until no more soil is removed.
Glycerin is a good lubricator. Household soaps that are pH-neutral can be good for lubrication, with a little water added. Water swells fibers, though; this can allow the stain to be embedded deeper, often making removal impossible. Natural fibers swell more readily than synthetics.
Water-soluble stain-removal agents contain neutral detergent for lubrication and penetration. For protein stains, neutral detergent may include an alkaline chemical to raise its pH and help remove protein materials. For stains that are acidic, the detergent may include a mild acid to help remove stains.
Solvent-soluble soils will not be removed readily by a water-based product. These must have a dry agent and a lubricant to help break them up, so they can be flushed with solvent.
Sources of Stains. If you understand what a stain is made of, removal will be simpler. Trial-and-error methods will be avoided, along with the garment damage.
Water-soluble stains can come from plain water, which can dissolve dyes and finishes. In addition, they may be of alkaline or acidic nature. Generally, any stain coming from a plant, tree or other vegetable form will be on the acid side of the pH scale and call for an acid agent.
Water-based, acidic pH stains such as coffee, tea and liquor can be removed by wetting the area and applying a tannin spotter. Tannin is acidic, and re-activates the dried part of the stain, suspending it in order for it to be flushed out.
If a water-based staining material comes from an animal or human, it will be on the alkaline side of the pH scale, and therefore it can be removed with an alkaline agent.
A water-based, alkaline stain such as meat juice, blood, urine or slobber can be removed by wetting the stained area and applying a protein spotter. Protein spotters are alkaline, so they re-activate dried alkaline stains, suspending them for flushing.