Cleaning with dish soap: what it removes and how much to use

Step by step

1. 1

   Use clear hand-dishwashing liquid

   Pick a clear or white liquid dish soap. Don't substitute automatic-dishwasher detergent or laundry detergent, especially on carpet.

   Why: Dishwasher detergents are alkaline and may contain bleach that destroys dyes, and laundry detergents can contain optical brighteners that dye carpet fibers.

2. 2

   On washable fabric, work a little into the stain

   Blot off excess grease, then put a few drops of dish soap directly on the stain and work it in gently with your fingers.

   Why: The surfactant needs contact with the oil to wet it and lift it off the fibers.

3. 3

   Leave it about 30 minutes

   Let the soap sit on the stain for about 30 minutes before rinsing or washing.

   Why: Surfactant molecules take time to work into the fibers and surround the oily soil.

4. 4

   Wash in the hottest water the label allows

   Wash the item as usual, at the hottest temperature its care label permits, and check the stain before drying.

   Why: Warm water softens oil, and the detergent in the wash carries away what the soap has loosened. Dryer heat can set what's left.

5. 5

   For carpet, mix 1/4 teaspoon per cup

   Stir 1/4 teaspoon of clear dish soap into 1 cup of lukewarm water. Never make it stronger.

   Why: This is the Carpet and Rug Institute's detergent solution. Stronger solutions leave residue that's hard to rinse out.

6. 6

   Blot it onto the spot, edges first

   Apply a little solution with a white cloth and blot, working from the outside of the spot toward the center. Don't saturate the carpet.

   Why: Working inward keeps the spot from spreading, and less liquid stays out of the backing and pad.

7. 7

   Rinse several times and blot dry

   Rinse the area with plain water and blot, and repeat several times until no soap remains. Blot until no more moisture transfers to the cloth.

   Why: Soap left in carpet attracts soil, so a cleaned spot quickly turns into a dark one.

What dish soap is and how it cleans

Liquid dish soap is a synthetic detergent, mostly anionic surfactants in water. University of Georgia Extension describes clear or white dishwashing liquid as mild and close to neutral, about pH 6.5 to 7.5. It's a different product from automatic-dishwasher detergent, which is alkaline and may contain bleach.

Each surfactant molecule has a water-loving head and an oil-loving tail. They lower the water's surface tension so it wets fibers better, then cluster around droplets of oily soil with their tails inward. Those clusters stay suspended in the water, so the oil rinses away instead of settling back. That's why dish soap is the go-to for oil-based stains.

What dish soap is good for, with the ratios

• Grease and food oils on washable fabric: the Kentucky extension guide recommends liquid dish soap as a pretreatment before washing in the hottest safe water. See grease on clothes.
• Carpet and upholstery spots: the Carpet and Rug Institute's detergent solution, 1/4 teaspoon per 1 cup of lukewarm water, is its first step for blood, coffee, wine, urine, vomit, mud, latex paint and most other spills. See how to clean carpet.
• Unknown stains: New Mexico State University's guide works a little liquid detergent, shampoo or dish liquid into the stain, leaves it about 30 minutes and rinses.
• A homemade wet spotter: University of Georgia Extension mixes 1 part glycerin, 1 part dish detergent and 8 parts water for many stains. See glycerin.

Where dish soap goes wrong

• Too much on carpet: soap residue makes a spot resoil quickly. The Carpet and Rug Institute says never to go stronger than 1/4 teaspoon per cup and to rinse several times.
• The wrong detergent: automatic-dishwasher detergent can contain bleaching agents that strip carpet dye, and laundry detergent can contain optical brighteners that dye the fibers.
• Chlorine bleach: wash and rinse first, then use bleach separately if you need it. The EPA warns against mixing bleach with ammonia-containing detergents, and some cleaners contain ammonia. See which cleaning chemicals never to mix.

By situation

Fresh grease on clothes

Blot or absorb the excess, work dish soap into the stain, leave it about 30 minutes and wash hot if the label allows. Air-dry and check before using the dryer.

Old or set-in grease

Repeat the dish soap pretreatment and wash. If a mark survives two rounds, a solvent may be needed for the oil that soap can't reach.

Carpet spills

Use the 1/4 teaspoon per cup solution, blot from the edges in, then rinse with plain water several times. If the spot looks darker a few days later, soap residue is the usual reason: rinse again.

Upholstery

Check the cleaning code first. On fabric that tolerates water, use the same dilute solution and as little liquid as possible, then rinse by blotting with a damp cloth.

Wool and silk

Use only a small amount of mild dish soap and rinse it out well. Both fibers are sensitive to alkaline residues.

What not to do

• Don't use more than 1/4 teaspoon per cup on carpet. Stronger solutions leave residue that attracts soil and is hard to rinse out.
• Don't substitute dishwasher or laundry detergent on carpet. Bleaching agents can destroy dyes and optical brighteners can dye the fibers.
• Don't skip the rinse. Soap left in fabric or carpet holds on to dirt and leaves a dull or sticky spot.
• Don't mix dish soap and bleach in one bottle. Some detergents contain ammonia, and bleach with ammonia releases toxic chloramine gas.

Other methods that work

Absorbent powder first

On fresh, heavy grease, cornstarch or talc can pull out loose oil before the soap goes on, so there's less to emulsify.

Caution: Give the powder a few hours, and don't skip the soap and wash afterward.

Dry-cleaning solvent

For oil on fabrics that can't be washed, or oil the soap won't move, a solvent dissolves it directly.

Caution: Ventilate, keep it away from flames, and test on a hidden area.

Enzyme cleaner

For protein stains such as blood, urine or vomit, enzymes break down what soap only loosens.

Caution: Check the label before using it on wool or silk.

Stain still there?

The carpet spot came back darker

Soap residue is attracting dirt. Rinse the area several times with plain water and blot thoroughly until no suds appear.

A grease mark is still there after washing

Don't dry it. Repeat the pretreatment, leave it 30 minutes, and wash again in the hottest safe water.

The fabric feels stiff or sticky where you treated it

There's soap left in it. Rinse the area well under running water and wash again.

Safety

• Keep dish soap out of your eyes and away from children.
• Use it separately from chlorine bleach, and rinse between products.

Never mix cleaning products; see chemicals you must never combine.

Questions

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• Cornstarch and other absorbents: how they lift grease stains
• Dry-cleaning solvent: what it removes and how to use it safely
• Enzyme cleaners: what they break down and how to use them
• Glycerin for stain removal: what it loosens and how to use it
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