The Encyclopedia Britannica states that the action of heat (and/or time), in conjunction with sugar ingredients, imparts the typical (brownish) color to caramelized sugar stains. The process is termed caramelization. For example, a drop of apple juice will turn brown (caramelize) with heat and/or age.
Identifying Caramelized Sugar and Tannin Stains
Spillage of fruit juices, soft drinks, and alcoholic beverages form stains that are subject to caramelization. Tannin stains like tea, coffee, or tomatoes do not caramelize, but are removed with the same spotting agents.
The stain is usually invisible, before it is subjected to heat. After being exposed to the heat of drying and/or finishing, the reducing sugar in the juice or beverage will caramelize and turn yellow, tan, or brown. The appearance of this caramelized sugar stain is very similar to many tannin stains.
The darker the brownish color, the greater the degree of caramelization. The size of the stain could be a small dot or a very large irregular area caused by a spilled drink. Caramelized stains are absorbed in the fabric—not built up, and are visible and brown on the reverse side of the fabric. Once a reducing sugar has caramelized on wool or silk, the stain will be almost impossible to remove. The only possible solution is soaking overnight in a three percent hydrogen peroxide solution.
Alkalis on Brownish Stains
Ammonia 26° or protein formula does not set caramelized sugar stains as it does tannin stains (tea, coffee, etc.). Alkaline spotting agents are not used on any brownish stains because:
- Some fruit juices contain a small amount of tannin material.
- Ammonia or protein formulas will “set” any tannin in a brownish stain.
- An alkali (ammonia or protein formula) plus heat may cause caramelization of a “reducing sugar” on cotton, rayon, or acetate.
If you assume that all brownish spots are tannin stains, none of the above problems will occur.
Note: Use acids to remove tannin or reducing sugar stains.
Caramelized sugar stains should not be confused with tannin stains. Tannin stains are visible, when fresh and are caused by substances containing tannins. Organic material such as walnuts and grass, etc., cause tannin stains. These brownish stains become browner with age or heat.
Some oil stains may also turn yellowish or brown with time or when exposed to heat. These stains have a very different appearance from reducing sugar or tannin stains. Oil stains will usually wick along each individual yarn and form a cross pattern. Special spotting agents are required to remove these oxidized oil stains.
Reducing Sugars Found on Various Fibers
Natural sugars, such as glucose, fructose, or maltose, are mild reducing agents. Fruit juices, sweetened soft drinks, and alcoholic beverages like champagne, caramelize and react differently on various fibers. Reducing sugars on most manmade fibers turn brown with either heat or time. Wool, silk, and nylon need a temperature above 140° F to cause caramelization, plus browning usually does not occur from aging alone. Usually an alkali or citric acid plus heat must be present to cause caramelization on cotton, rayon, or acetate. However, reducing sugars on cellulose fibers will caramelize with time. Your drycleaning solvent should contain enough relative humidity and detergent to help remove most sweet spots during a regular cleaning run. Keep your tumbling temperatures at 140° F to help prevent caramelization of any remaining natural sugar.
Removing Reducing Sugars and Tannin Stains
Reducing sugar and tannin stains should be prespotted. Reducing sugar stains and tannin stains are both spotted in the same manner on the wetside. Prespotting is done with steam or water and neutral synthetic detergent, followed by a tannin formula or 28 percent acetic acid. You must remember to make sure the garment is allowed to dry completely before drycleaning. This procedure will ensure that there is no redeposition, or color loss, or localized shrinkage on natural fibers.
Reducing sugars that have been exposed to heat and/or age plus all tannin stains usually require the following spotting agents (use from mildest to the most aggressive) for complete removal:
- Steam or flush with water
- Synthetic detergent
- 28 percent acetic acid or tannin formula
- General formula
- Rust remover
- Flush thoroughly with steam or water
- Oxidizing bleach (test first for color change)
- Flush out with steam or water and dry
Drycleaning Claims
Caramelized sugar stains frequently cost the drycleaner claims, and sometimes customers. Try to educate your customers about the importance of immediately rinsing sugar stains, but never rubbing the spot while wet. The alternative is for the customer to take the garment for cleaning right away, point out the spot, and request that the cleaner prespot the stain. To help educate the customer about invisible stains, the IFI brochure entitled “Trouble Spots” discusses this type of stain.
