Acid and alkali in problem solving
any garments
received by my independent garment analysis service
require the use of acids and alkalis for their
correction.
Some examples of problem-solving may be:
• Restoring color to acetate.
• Correcting shrunken leather.
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• Removing shine.
• Removing ground in soils.
• Prevention of bleeding during
wetcleaning.
• Expanded stain removal.
• Aid to bleaching.
• Stretching wool.
Most spotters limit their use of acids and
alkalis. 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 the 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. 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
spotters 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 micro organism 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.
Although it can be purchased in
concentrations of 56% or 99%, this 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
Use acetic acid after using a tannin
formula. Acetic acid will have a greater effect on many tannin
stains, especially wine.
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Shine. Shine
on gabardine can often be corrected by spraying with acetic
acid.
Neutralize alkali. All alkalis should be neutralized after use to prevent
yellowing.
Shrunken leather. If caused by heat, this 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.
Wetcleaning. Add
acetic acid to wetcleaning detergents for setting dyes on color
sensitive fabrics during wetcleaning procedures.
Neutralize bleaches. 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.
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.
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 one 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
Flush.
Neutral lubricant.
Mechanical action.
Flush.
Tannin formula.
Mechanical Action.
Acetic acid plus neutral lubricant.
Mechanical action.
Flush.
Oxalic acid (test).
Heat.
Flush.
Rust remover (test).
Flush.
Peroxide plus ammonia (test).
Flush.
Acetic acid.
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
Flush.
Protein formula.
Mechanical action.
Flush.
Ammonia plus neutral lubricant.
Mechanical action.
Flush.
Peroxide plus ammonia (test).
Heat.
Flush.
acetic acid.
Flush.
Digest.
Dan Eisen recently retired as chief
garment analyst for the Neighborhood Cleaners Association after
33 years with that organization. He is available for seminars,
consultations and independent garment analysis. He also has
published a book, “The Art of Spotting,” which is
an indexed compilation of articles he wrote for National
Clothesline and NCA over the past three decades. He can be
reached at (772) 340-0909. His address is 274 NW Toscane Trail,
Port St. Lucie, FL 34986. His e-mail address is cleandan@adelphia.net.
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