Oxidized tannin stain

Tannin stains are those wetside stains that are derived from vegetable or plant matter. It is the most common wetside stain and includes tea, coffee, all soft drinks, fruits, vegetables, hard drinks, wine, many medications and condiments such as ketchup, mustard and soy sauce. An oxidized tannin stain is a stain that changes chemically by picking up oxygen making it difficult and sometimes impossible to remove.

Oxidation also turns an invisible tannin stain into a visible stain and changes a soluble stain into an insoluble stain. An example of oxidization can easily be observed by cutting an apple in half and leaving it exposed to the air causing it to turn brown. Many people know the trick of writing something on paper using lemon juice and applying heat to the writing, causing it to mysteriously appear.

Tannin stains undergo constant chemical change. Fruits produce ethylene gas that converts starch to sugar. Ethylene produced by fruits is the reason why fruits ripen when kept in the same bag. The problem with tannin stains is that many cleaners handle it improperly causing further oxidation and preventing it from being removed. There are many factors that will oxidize a tannin stain making it more difficult to remove.

  • Heat – This is the fastest way to oxidize or set a tannin stain. This is the reason why tannin stains must be pre-spotted before drycleaning. The heat of drycleaning and drying at 140 ℉ sets tannin stains. The drycleaning process does not remove tannin stains.
    Cleaners who use the steam gun improperly also set tannin stains. Many cleaners think that holding the steam gun 3-5 inches away from the fabric is done only for the safety of the fabric. Many strong fabrics can withstand the pressure from the steam gun. Steam guns are held at a distance from the fabric to avoid setting the stain. The distance is determined by holding your hand under the steam gun and being able to withstand the heat. This is also the reason why a water gun is the safest way to flush a tannin stain before proceeding onto the next step.
  • Chemical – Alkali sets tannin stains. Alkali is found in ammonia and protein formula. When alkali is applied to the stain the color of the stain changes and becomes insoluble.
  • Fabric – Tannin stains are more difficult to remove on natural fabrics such as wool, linen, silk and cotton. This is due to the fact that the fiber characteristics absorb the tannin substance forming a bond with the fabric. This differs from nylon, polyester and acrylic which does not easily absorb the tannin substance. A tannin stain on these fabrics can be removed easily even if the stain was on the fabric for a period of time.

IDENTIFICATION

Most tannin stains will turn brown with a heavy outer ring. The darker the tannin stain the more it has oxidized and more difficult it is to remove. The tannin stain is usually absorbed in the fabric and has no feel. The identification of tannin stains may change due to the other characteristics of the tannin substance. For example, mustard and ketchup have feel and the color is characteristic to its composition. Red wine and medicines may also differ in appearance.

TANNIN STAIN REMOVAL

  1. Flush (Water gun)
  2. Neutral lubricant
  3. Mechanical action
  4. Flush
  5. Tannin formula
  6. Mechanical action
  7. Flush
  8. Test fabric for safety on an unexposed seam when using the following chemicals
  9. Oxalic acid
  10. Heat
  11. Flush
  12. Rust remover
  13. Heat
  14.  Flush
  15. Peroxide and ammonia
  16. Heat
  17. Flush
  18. Acetic acid
  19. Flush

SPECIALIZED HANDLING FOR OTHER TANNIN STAINS

  • Mustard – Scrape off the surface of the mustard with a dry brush before proceeding onto the tannin stain removal.
  • Iodine – Place a small amount of sodium thiosulfate in a cloth making a small sack. Then wet cloth by spraying with a water gun. Dab the stain with the wet cloth and then flush. Then proceed onto the regular tannin method.
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Dan Eisen

Dan Eisen, former chief garment analyst for the National Cleaners Association, offers lecture, consultation and garment analysis service. He is the author of The Art of Spotting. He can be reached at (772) 340-0909, by email at cleandan@comcast.net or through his website at www.garmentanalysis.com. Dan Eisen, 274 NW Toscane Trail, Port Saint Lucie, FL 34986.

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