Enzyme cleaners: what they break down and how to use them

Step by step

1. 1

   Check the fabric

   Read the care label. Don't use an enzyme presoak on silk or wool.

   Why: Silk and wool are protein fibers, and the protease that digests a protein stain can damage them too.

2. 2

   Rinse fresh protein stains in cold water first

   Flush fresh blood, egg, dairy or vomit from the back of the fabric with cold water before the enzyme step.

   Why: Cold water removes what's still soluble, and hot water would cook the protein onto the fibers before the enzymes reach it.

3. 3

   Mix the solution just before you use it

   Follow the product label, or use University of Georgia Extension's soak of 1 tablespoon of enzyme prewash per 1 quart of warm water. Make only what you need now.

   Why: Enzymes lose activity once they're dissolved and stored, so a solution mixed ahead may do nothing.

4. 4

   Soak long enough

   Submerge the stain for at least 30 minutes, and for several hours if it's old or dried.

   Why: Enzymes need contact time to break the stain down; scrubbing doesn't speed them up.

5. 5

   Wash without chlorine bleach

   Wash as the care label directs, with an enzyme detergent if you have one. Don't add chlorine bleach to the same wash.

   Why: Chlorine bleach inactivates enzymes, which cancels the treatment.

6. 6

   Air-dry and check

   Let the item air-dry and look at it in good light. Repeat the soak if any trace remains before using the dryer.

   Why: Dryer heat can set leftover protein so it won't come out later.

What enzyme cleaners are and how they work

Enzymes are biological catalysts: proteins that speed up one specific chemical reaction without being used up. Cleaning products use several kinds. Proteases break down proteins, amylases break down starches, lipases break down fats and oils, and some products add cellulases. In US stores they come as enzyme laundry detergents, enzyme presoak powders and enzymatic pet-stain and odor cleaners.

A protein stain sticks because its large molecules tangle with and cling to the fibers. Enzymes cut those molecules into smaller, water-soluble pieces that detergent and water can rinse away. That's why they work on dried blood, which water alone can't move. It's also why they need time, moderate temperatures and fresh solution: they lose activity once dissolved and stored.

What enzyme cleaners are good for, with soak times

• Protein stains: blood (including dried), egg, dairy, baby formula, ice cream, vomit, feces and other body fluids. See blood stains.
• Grass, tobacco, fruit and juice, and older beverage stains: the American Cleaning Institute lists an enzyme pretreatment or soak for these.
• Stubborn perspiration: an enzyme product, or oxygen bleach, in the hottest water the fabric allows.
• Pet urine and accidents on carpet, upholstery and washables: the ASPCA and Humane World for Animals recommend enzymatic cleaners made to break down pet-waste odors. See pet odor on carpet.

Soak times differ by source. The American Cleaning Institute says at least 30 minutes, and several hours for aged stains. The Kentucky extension guide gives 15 to 30 minutes. Starting at 30 minutes and extending it for old stains covers both.

Temperature differs too. Fresh protein stains get cold water first. The Kentucky guide says enzyme products work best in warm to hot water, so the soak itself can be warm. Follow the product label.

What enzyme cleaners damage, and what cancels them

• Silk and wool: both are protein fibers, and the Kentucky guide warns not to use enzyme presoaks on them. The same applies to wool carpet.
• Chlorine bleach: not a gas hazard in this case, but it inactivates the enzymes. Don't combine them in a soak or wash.
• Heat on urine before the enzymes have worked: hot water and steam cleaners set urine stain and odor, and Humane World for Animals advises against steam-cleaning urine spots.

If you also use bleach on the item later, rinse thoroughly in between and follow the rules on which cleaning chemicals never to mix.

By situation

Dried or old protein stains

Give them a long soak, several hours or overnight, and repeat with fresh solution if needed. Mix each batch just before use.

Pet urine on carpet or upholstery

Blot up as much as you can, test the cleaner on a hidden area for colorfastness, then apply an enzymatic pet-stain cleaner as its label directs and give it the full dwell time. Don't steam-clean the spot, and avoid ammonia-based cleaners, which can draw pets back.

Silk, wool and wool carpet

Don't use enzyme presoaks. Sponge with cold water and take valuable items to a cleaner, telling them what the stain is.

Stains that went through the dryer

Heat has partly set the protein. Repeat long enzyme soaks two or three times, then try oxygen bleach for any color left.

Juice and older beverage stains

These aren't protein stains, but the American Cleaning Institute still lists an enzyme pretreatment or soak for fruit, juice and older beverage stains, alongside grass and tobacco.

What not to do

• Don't use enzyme presoaks on silk or wool. These fibers are made of protein, and the enzymes that digest protein stains can damage them.
• Don't mix enzymes with chlorine bleach. Chlorine bleach inactivates the enzymes, so neither does its job well.
• Don't mix a solution ahead of time. Enzymes lose activity once dissolved and stored.
• Don't steam-clean or hot-wash urine before the enzymes have worked. Heat sets the urine stain and its odor.
• Don't rinse after a few seconds. Enzymes need dwell time, from 30 minutes to several hours.

Other methods that work

Oxygen bleach

For the color left after the protein is gone, such as the brown shadow from blood, or for stubborn perspiration, oxygen bleach oxidizes the pigment.

Caution: Check the label for silk and wool, and test colored fabrics first.

Cold water alone

Fresh protein stains often come out completely with an immediate cold-water rinse and a normal wash.

Caution: Once the stain has dried, water alone won't move it.

Dish soap solution on carpet

For carpet spills that aren't urine or other body fluids, a mild dish soap solution is the usual first step.

Caution: It cleans the stain but doesn't break down urine odor the way enzymes do.

Stain still there?

The enzyme soak did nothing

The solution may have been mixed too early, used too briefly, or mixed with bleach. Mix a fresh batch, soak for several hours, and keep bleach out of it.

The pet keeps going back to the same spot

Odor is still there, often deeper than the surface. Treat again with an enzymatic cleaner and give it the full dwell time, and avoid ammonia-based or scented cleaners that can attract pets.

A brown or yellow mark remains after the protein is gone

That's pigment, not protein. Follow with oxygen bleach after a spot test.

Safety

• Follow the label, and keep enzyme detergents away from children.
• Test carpet and upholstery for colorfastness before treating.

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

Questions

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