Problem solving using acid and akali

Many garments received by my analysis service (International Independent Garment Analysis Service by Daniel Eisen) require use of acids and alkalis for their correction. Some examples of problem solving may be:

1.   restoring color to acetate
2.   correcting shrunken leather
3.   restoring color change
4.   removing shine
5.   removing ground in soils
6.   prevention of bleeding during wetcleaning
7.   expanded stain removal
8.   aid to bleaching
9.   stretching wool

Most spotters use acids and alkalis in limited use. They may use tannin and protein formulas and rust remover but they limit their potential for problem solving. Acids and alkalis are different in their chemical makeup and they must be used on specific staining. Spotters must be aware of their potential to damage fabrics and color on fabrics. Acids and alkalis neutralize each other. This means if an alkali is put on the fabric followed by an acid the result of the chemical reaction would be water and salt. This is also true if an acid is put on the fabric followed by an alkali. Acids and alkalis are water soluble and not removed by drycleaning solvents.

ACIDS

Acid is defined as a chemical that releases hydrogen ions in the presence of water. We measure acids using the PH scale. 7 is neutral and less than 7 measures the strength of the acid. The lower number on the PH scale indicates a stronger acid. Acids are safer on bright colors than alkalis and it is for that reason we use acids to stabilize dyes in wetcleaning. Strong acids can affect dyes and the strength of many fabrics. Prepared tannin formulas are made up of a mild acid and lubricant. This is effective for removal of many tannin stains or vegetable based staining such as coffee, tea, soda, beer, wine, etc. The degree of stain removal can be expanded when the spotter uses other acids for stain removal.

ACETIC ACID

Acetic acid should be added to the spotter’s arsenal for stain removal. Acetic acid is similar to vinegar. Vinegar is produced by the action of bacteria on yeast fermented brews. Vinegar can be made out of just about any plant that can be fermented to generate alcohol which is subsequently generated into acetic acid. The hero of the fermentation process is acetobacter a small microorganism that has the chemical power to transform alcohol into acetic acid. Acetic acid gives vinegar its pungent odor. Acetic acid has properties and advantages not possessed by other acids.

Acetic acid should be purchased at 28%. Concentrations over 28% will discolor dyes on fabrics and even dissolve acetate fabrics. It can be purchased in concentrations of 56 or 99% but is not recommended since mixing and diluting with water may not be accurate. Use 28% and even dilute it with more water so it can be used in the 20% range.

USES OF ACETIC ACID

1.   Use acetic acid after using a tannin formula. Acetic acid will have a greater effect on many tannin stains especially wine.
2.   Delustering of acetate. Acetate fabric damage by heat and moisture can often be corrected by spraying with acetic acid, hanging to dry and then cleaning.
3.   Shine- Shine on gabardine can often be corrected by spraying with acetic acid.
4.   Neutralize alkali-All alkalis should be neutralized after use to prevent yellowing.
5.  Shrunken leather-caused by heat can often be corrected by spraying with acetic acid which will make it soft and pliable so it can be shaped. Additional leather sprays must be used afterwards.
6.   Add acetic acid to wetcleaning detergents for setting dyes on color sensitive fabrics during wetcleaning procedures.
7.   Use acetic acid to neutralize the following bleaches-peroxide and ammonia, sodium perborate and sodium percarbonate. Acetic acid is used to accelerate chlorine bleaches and all reducing bleaches.
8.   Stretching wools-Acetic acid can be added to a cationic detergent in soaking a shrunken wool that has to be made soft enough to stretch.
9.   Acetic acid can be used in combination with hydrogen peroxide (paracetic) for bleaching some fabrics.

OXALIC ACID

Oxalic acid comes in crystal or liquid state. Laidlaw makes a product called RustGo which is oxalic acid in a liquid form. In crystal form the oxalic acid should be mixed 15 parts water to l part oxalic acid. Oxalic acid can be used after acetic acid for tannin stain removal. It will remove rust staining without the damage potential of rust remover. Oxalic acid is applied to a stain and heated with the stream gun. It must be flushed after use. Remember heat accelerates all chemicals and oxalic acid should be tested for safety prior to its use on fabrics.

RUST REMOVER

Hydrofluoric acid is the makeup of rust remover. This is a very effective acid but requires skill and knowledge for its use. Rust remover can be very corrosive if left on a fabric and contact on a customer’s skin can cause severe burns. After using rust remover it must be flushed thoroughly with water and a protein formula or a mild alkali must be added to the area to neutralize any residue the acid left. Rust remover must be tested before use and can discolor cashmere, gabardine, glass trimming and metallic trimming. 

TANNIN PROCESS

1.   Flush
2.   Neutral Lubricant
3.   Mechanical Action
4.   Flush
5.   Tannin formula
6.   Mechanical Action
7.   Acetic acid plus neutral lubricant
8.   Mechanical Action
9.   Flush
10.  Oxalic acid (Test)
11.  Heat
12.  Flush
13.  Rust Remover (Test)
14.  Flush
15.  Peroxide plus ammonia (Test)
16.  Flush
17.  Acetic Acid
18.  Flush

ALKALI

Alkali releases hydroxyl ions in the presence of water. Alkali on the PH scale is above 7. The higher the number, the stronger the alkali. Alkali is found in protein formulas and ammonia. Alkali is effective on protein stains or stains originating from the body. This includes eggs, milk, urine, etc. The wool and silk are sensitive to alkali.

PROTEIN FORMULAS

Most commercial protein formulas are made up of a mild alkali and lubricant.

AMMONIA (26)

Ammonia is a very volatile alkali and is stronger than the alkali found in most protein formulas. Ammonia is effective for neutralizing the effects of discolorations caused by acids. This usually occurs on cottons, rayons and linens. Sometimes titanium sulphate will produce a discoloration that can be neutralized by using ammonia. For removing ground in soil nothing works better than using ammonia mixed with a wetside lubricant. Ammonia is very volatile and should be kept in a cool place since it can expand rapidly. Ammonia is used to increase the bleaching action of peroxide, perborate and percarbonate. Do not use ammonia on chlorine bleach since it will break down and will release chlorine gas. 

PROTEIN SPOTTING PROCEDURE

1.   Flush
2.   Protein formula
3.   Mechanical action
4.   Flush
5.   Ammonia plus neutral lubricant
6.   Mechanical action
7.  Flush
8.   Peroxide Plus Ammonia (Test)
9.   Heat
10.  Flush
11.  Acetic Acid
12.  Flush
13.  Digest