In my encounters doing consultations I find that many set stains are caused by procedures used by drycleaners and spotters. The first thing that we have to do is define a set or oxidized stain. These are stains that require more than drycleaning fluid, water or lubrication to remove. Tannin, protein and oils oxidize and set by picking up oxygen from the air. An example of oxidation is cutting an apple in half and watching it turn brown from picking up oxygen from the air. This is the theory behind invisible stains that show up after a period of time. Vegetable and cooking oils also oxidize by picking up oxygen from the air. These oils differ from mineral oils such as Vaseline and motor oil which do not oxidize. Paints and glues also oxidize after a period of time. We all know that a fresh paint stain can be simply washed off or drycleaned to remove. There are several factors which produce oxidation and set stains, some of which are more important than others. At the laboratories of Independent Garment Analysis, I conducted several experiments concerning oxidation on various stains.
The longer a stain remains in the fabric, the more oxidized and set it becomes. The means that customers who bring in a garment with older stains will be more difficult to remove than fresh stains. The extent to which a stain oxidizes due to age is a factor but not necessarily a major one. We stained several garments with vegetable oils, tannin and protein allowing it to set in the fabric for two weeks. Although the stains oxidized it did not do it to an extent that it could not be removed.
This is a major factor to oxidization. We found that the heat of the spotting gun improperly used caused oxidized and set stains. We found that if mustard placed on a fabric and steamed with the steam gun at close range caused the mustard to oxidize so only bleach could remove it. When spotted properly without using excessive heat the mustard was removed easier. The same concept can be applied to vegetable oils. When vegetable oils splatter on a fabric from hot foods such as pizza and hot sauce the stain was much more difficult to remove than oils used in salads.
The drycleaning process often uses heat from 140℉ to 150℉ which can set stains.
The heat of pressing is one of the biggest factors causing stains to oxidize. This is the reason why many vegetable oils on laundered shirts are most difficult to remove, especially when pressed on a hothead.
Wetside stains on natural fabrics such as wool, cotton, silk and linen will oxidize to a greater extent than synthetic fibers such as polyester and nylon. Vegetable oils oxidize to the same extent on all fibers.
Certain chemicals can set stains making it impossible to remove. For example, when alcohol is put on a blood stain or other protein matter, the stain in many cases was impossible to remove. Tannin stains such as coffee, tea, medicine and mustard will oxidize from contact with alkali. Put an alkali on a coffee stain or mustard and watch the stain change in color.
AVOIDING OXIDIZED STAINS
(1) Pre-spotting – Light colored fabrics should be pre-spotted before drycleaning. Dark garments usually do not have to be pre-spotted.
SPOTTING PROCEDURE TO AVOID OXIDIZATION
(1) Flush area but keep steam gun 6 inches from fabric. If you can hold your hand under the steam gun it is the right distance.
(2) Apply lubrication.
(3) Use mechanical action.
(4) Flush (Safe Distance)
(5) Tannin formula
(6) Mechanical action
(7) Flush (Safe Distance)
Any stain not removed at that point is oxidized and heat can be applied.
(8) Oxalic Acid-test
(11) Rust remover (Test)
(14) Peroxide and ammonia (Test)
(1) Flush (Safe Distance from fabric)
(2) Neutral Lubricant
(3) Mechanical Action
(5) Protein formula or Digester
(6) Mechanical action
(8) Peroxide and Ammonia
(1) Oily type paint remover
(2) Mechanical action
(3) Oily type paint remover and amyl acetate
(4) Mechanical action