Digestion is a process that uses enzymes to convert insoluble stains to soluble substances. The advantages of using and understanding digestion is that the process removes stains safely by eliminating mechanical action, lubrication and chemical action that can affect the safety of many fabrics. I have been successful in using digestive action for 35 years in my role as a garment analyst, spotting instructor, and handling fabrics for the Metropolitan Museum of Art as well as other museums. The preservation center at the East Coast School of Drycleaning presently has several bath systems devoted to digestion. Many cleaners shy away from using this process claiming it does not work or it takes too long. The fact of the matter is that most cleaners do not fully understand the digestion process and those that do use it are not using it properly. Digestion can be used alone as a stain remover or in combination with other methods thus increasing the range of stain removal. Enzymes associated with stain removal in digestion are proteins that act as a catalyst in a biochemical reaction. A catalyst affects chemical change but they themselves are not used up and do not appear in the final product. This differs from using acid, alkali or bleach which undergo chemical changes themselves. In general enzymes accelerate reaction by lowering the free energy necessary to initiate the reaction, which may be compared to lubricating oil in an engine. An enzyme can be identified by its name typically ending in a suffix “-ase.” Today over 2,000 enzymes have been identified. Each enzyme will react with a different type of staining. The first portion of the name of the enzyme is the substance upon which the enzyme works. This is called the substrate.
| Enzyme | Staining |
| Diastase | Starch |
| Lactase | Lactose |
| Lipase | Fats |
| Protease | Protein |
| Urease | Urea |
The digesters which are manufactured for stain removal contain a mixture of enzymes so they can be used in a wide variety of stains. In general enzymes are used for stains originating from a living body. This includes albumin, milk, blood, urine, perspiration, animal glue, some fats, etc. Remember enzymes do not remove stains but converts it to a soluble substance that can be removed by simply flushing with water. The classic riddle that I use in my spotting classes that explains enzymes is as follows:
● Question: How do they get the liquid center inside the liquid filled chocolate covered cherry?
● Answer: The cherries are put in a solid mold which contain an enzyme. The cherries are then dipped in chocolate. They are then put in storage for controlled time and heat. The enzymes then convert the solid substance on the cherries to a liquid sugar.
USING ENZYMES
(1) Low Temperature Enzymes
These enzymes are found in a powdered form. Laidlaw manufactures a product called RSR and the enzymes have a specific use. They are very useful for spotting delicate wools, silks and rayons with color problems. These enzymes are also useful for staining on Indian and South American blankets that have old crusty stains. These enzymes require specific conditions to make it work:
(a) moisture: it needs water to activate the enzymes
(b) heat: 100-120℉. If the temperature goes above 120℉ the enzymes are destroyed. 100℉ only slows the enzyme process but it will still work.
(c) No chemicals: acid, alkali or bleach will destroy the enzymes.
(d) Time: over 20 minutes.
After making up these enzymes they can only be used for one day. I like making up the enzyme formula and putting it in a coffee thermos bottle. This will keep the enzymes at a proper temperature for several hours. I then transfer it to a spotting bottle for application. The formula for the spotting board is one pint of water, 1/2 teaspoon of enzymes and 1 teaspoon of glycerin. The glycerin is added so the area will stay wet longer. Remember you do not have to add large amounts of enzyme to make it work effectively. The quantity of enzyme compared to the staining is very small. It is claimed that the enzyme sucrase will digest 200,000 times its own weight. After applying the enzymes to the stain simply hang it up for ½ hour and then flush area. You do not have to roll it up to keep it warm nor hang it in a boiler room.
Bath method
Use a clean bucket free of chemicals. Add 1 teaspoon of enzymes to warm water and l teaspoon of salt as a dye setter (except on silk).
(2) High Temperature Enzymes
Streets makes a product “Devour” that works up until 158℉. The enzymes are very useful for stain removal but heating the enzymes up with the steam gun held too close to the fabric will destroy the enzymes. These enzymes also can not be used with other chemicals. These enzymes are not as safe as the low temperature enzymes and some color sensitive fabrics should be tested. On heavy white wools rinsing the enzymes might be difficult. These enzymes can also be used in a bath solution. The manufacturer recommends 1 tablespoon of “Devour” per gallon of water in a clean container.
(3) High Temperature Enzymes and Bleach
Some companies make enzymes that have a protective shell and are mixed with bleach. Metro Chem manufactures a product called “Recover” that contains enzymes mixed with an oxygen bleach. (sodium percarbonate). This has the advantage not only digesting the staining but oxidizing the remaining reside and whitening the fabric. These enzymes can be used for spot bleaching but will be destroyed if temperatures exceed 150℉. Use in a bath solution according to manufacturer’s directions.
