Let’s get back to
drycleaning basics
Continuing with the “Back to
Basics” series, this month we will cover removal of soil
in the drycleaning machine.
Removal of insoluble soil from fabrics
Mechanical action
There are four elements to achieve good
mechanical action:
1. Load factor: Overloading
the cleaning machine not only reduces mechanical action, but it
hinders complete wetting of the load and increases
re-deposition of soil. Excessive under-loading of the cleaning
machine eliminates mechanical action due to the floating of the
garments in solvent rather than gently striking each other and
the ribs of the cylinder.
The better way is to compute the
load’s proper weight with the cubic foot volume of the
cylinder multiplied by the best load factor. Where do we get
the cubic foot volume of the cylinder? Answer: from two sources:
(1)
the instruction manual written by the
manufacturer and (2) the computation geometrically.
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Once the cubic foot volume is determined,
that number is multiplied by the load factor of 2.5 pounds to
3.0 pounds.
The formula: Volume = pi x (diameter
divided by 24) squared x (length divided by 12) in inches.
Therefore, a cylinder measuring 36 inches
wide and 30 inches long (deep) would be computed as 3.14 x 36
divided by 24 x 36 divided by 24 x 30 divided by 12, or 3.14 x
2.25 x 2.5 to equal 17.66 cubic feet.
The 17.66 would be multiplied by the load
factor of 2.5 to 3.0 depending upon your volume, but not to
exceed three pounds per cubic foot of cylinder volume.
The above computation is for a dry-to-dry
machine’s drying/recovery capacity, but a transfer
petroleum solvent machine (washer-extractor) would permit a
load factor of 3.0 pounds to 3.5 pounds with its recovery
tumbler being of larger capacity rating to permit the proper
drying/recovery load factor of 2.5 pounds to 3.0 pounds per
cubic foot of cylinder capacity.
Since the load factor of 2.5 pounds to 3.0
pounds per cubic foot of cylinder capacity for a dry-to-dry
machine would be a better wash than the separate
washer-extractor, the recommendation here is to use the load
factor of 2.5 pounds to 3.0 pounds per cubic foot of cylinder
volume in the washer-extractor also.
2. Open pocket cylinder: This element of mechanical action applies to a
washer-extractor for petroleum or other alternate solvent from
perchloroethylene. The split-pocket cylinder washer-extractor
has its shaft running through the cylinder and is supported
with bearings front and back.
Since “drop” of fabrics within
the cylinder is very important to achieve good mechanical
action, this configuration merely squeezes one fabric against
the other, and each pocket must be of equal weight in order to
achieve good balance during extraction. Very few, if any,
washer-extractors below 100-lb. capacity are being manufactured
as split pocket models.
3. Ribs in cylinder: This element is very important to achieve
mechanical action. The ribs contribute to the lift and drop of
the fabrics. A minimum of three ribs within the cylinder is
required for good results.
4. Reversing action cylinder: This element is most important for keeping
the fabrics tumbling since the non-reversing cylinder can
result in tangling especially for full capacity loads.
Flushing action
There are two elements to achieve good
flushing action:
1. Flow rate and turbulence: The ideal flow rate for cylinder to button
trap to filters to solvent cooler and back to cylinder is one
gallon of solvent per pound of fabric load per minute (1-1-1).
Therefore, a 40 pound load should have 40
gallons of solvent circulating from and to the cylinder every
minute of the wash run.
To achieve this, the filter pump must have
a capacity of at least 40 gallons of solvent per minute (40
gpm), and the filters must be sized to handle at least 40
gallons of solvent per minute.
Most standard size and jumbo split size
cartridge filters can handle three gallons per minute for
perchloroethylene and four gallons per minute for
petroleum/hydrocarbon solvent.
For a spin disc, 30 micron filter, consult
with the technical manual for total square footage of surface
area and compare it to the cartridge filter’s square
footage of surface area of about 39 square feet.
A good flow rate is dependent upon the
proper load factor as explained above.
2. Solvent level: A solvent level of medium to high is recommended
for good wetting and good flushing action. Tests in both
laundry and drycleaning conducted at the National Institute of
Drycleaning (now IFI) and European laboratories have concluded
that a level higher than low will remove more soil in the
cylinder.
Full loads should have a high level of
solvent for better results. Low levels of solvent should be
used only for very light weight loads.
This rule applies to a batch run in spite
of some recommendations to use low levels in order to save
money on solvent usage and distillation. Remember, good
cleaning costs a little more, but saves money in the long run
by more spot and soil removal.
Detergent action
A good detergent is vital to achieve the
following:
(1) Aids in removal of insoluble soil by
lubricating soil particles.
(2) Avoids re-deposition of insoluble soil
by suspending through lubrication.
(3) Aids in removal of water-soluble soil
through addition of moisture to the load.
There are three types of detergents used
for drycleaning: anionic, cationic and non-ionic.
Anionic detergent is used as a “charge system.” This
means that a given percent of detergent is solubilized into the
solvent.
A minimum of 1.3 percent by volume for
perchloroethylene and petroleum/hydrocarbon is recommended.
Ideal charge percentage is 1.5 percent to 1.7 percent to permit
injection of 1/2 ounce of water stock solution per pound
of fabrics.
Again, do not skimp on detergent, but do
not overuse it either since a detergent charge in excess of 2.5
percent may require a short rinse in uncharged solvent to avoid
residues and blotches on fabrics. This system is excellent for
the removal of water-soluble soil. It requires close management
and titration to ensure maximum results, but it is well worth
the time devoted to its excellent results.
Cationic detergent is used as an injection system. The detergent is
usually blended with water through a catalyst to hold the two
as a mixture. Since the detergent is substantive, it will
adhere to the surface of fabrics to remove water-soluble and
insoluble soil by scrubbing the surface.
The initial wash must be on
“batch” in order to work the detergent/water
mixture onto the surface of the fabrics in the cylinder,
otherwise the detergent would be deposited onto the filter
surface when pumped out of the cylinder during a
“circulation” run.
Some cationic detergents are blended with
some non-ionic detergent to give them a little
solvent-solubility in addition to being substantive.
The recommended amount of cationic
detergent injected is in the amount of 1/5 ounce per pound of
fabrics. Although some manufacturers recommend using only 1/10
ounce per pound of fabrics, the 1/5 ounce per pound is more
effective. However, too much of the cationic detergent over 1/5
ounce per pound will produce poor “hand” and
blotches on the fabrics. Cationic detergent will suspend
insoluble soil satisfactorily.
Non-ionic detergent will suspend soil
satisfactorily, but it will not accept water additions in
solubility with solvent which is also non-ionic.
This detergent is not adsorbed by
activated carbon or activated clay used in adsorption
cartridges. It is more popular in commercial and industrial
laundry applications to dissolve or emulsify oil and grease.
As mentioned above, it is sometimes
blended into cationic detergents to give some solubility in
solvent.
Time
It takes three minutes to remove all of
the loose insoluble soil from fabrics provided all of the above
elements have been used, and it takes ten minutes (ten changes
of solvent) to remove all of the ground-in insoluble soil
provided all of the above elements have been used.
Therefore, all of the insoluble soil can
be removed at the end of ten minutes in either
perchloroethylene or in petroleum/hydrocarbon solvents.
Removal of insoluble soil from solvent
Filtration
Filtration is accomplished, currently, by
either cartridges, spin discs (30 micron or 60+ micron), metal
cone, tubes or a combination of spin disc with cartridges as a
carbon tower. The last type is the most popular today.
The tubular filters and spin disc filters
(60+ micron) use diatomaceous earth as a pre-coat for actual
filtration since this powder is porous to liquids but
non-porous to solids.
Distillation
Distillation is used to remove both
solvent soluble and insoluble soil removed by the batch run (no
filter circulation) in the cylinder.
The solvent and soil are drained and
extracted to the still rather than to the base tank of the
cleaning machine.
This method is used for a
“two-bath” run and also for cleaning white garments
when there is only one circuit of filters and for cleaning
fugitive-colored garments to avoid contaminating the filter
housings with dye.
Removal of solvent-soluble soil from
fabrics
Load factor
Same load factor as explained in Removal
of Insoluble Soil.
Flushing action
Same flow rate and turbulence as for
Removal of Insoluble Soil.
Time
It takes about 2 1/2 to three minutes for
complete removal of solvent-soluble soils in perchloroethylene
provided all the elements mentioned in Removal of Insoluble
soil are used.
It takes about 20 to 25 minutes for
removal of mineral oil and grease in petroleum/hydrocarbon
solvents provided all the elements mentioned in Removal of
Insoluble Soil are used.
Animal fat and most vegetable oils are not
soluble in petroleum/hydrocarbon solvents.
The above is based upon the KB Value of
perchloroethylene solvent being more than three times higher
than the KB Value of petroleum/hydrocarbon solvents.
Removal of solvent-soluble soil from
solvent
Distillation
Distillation is the only method to remove
100 percent of the solvent-soluble soils from all solvents.
A minimum distillation rate for good
solvent clarity and purity is 18 gallons of solvent per 100
pounds of cleaning.
Recovery during the dry cycle
(petroleum/hydrocarbon and perchloroethylene solvents) and
final vapor adsorption within the cylinder at the end of the
cycle (perchloroethylene solvent) plus any additions of new
solvent total the amount of solvent “turnover” of a
minimum of 21.5 gallons per 100 pounds of cleaning.
For users of the charge system this will
result in a considerable cost in detergent use, but again, good
cleaning is not cheap to begin with; it will save production
costs by less spotting and re-cleans in the long run.
Filtration by adsorption
This method uses a combination of
activated carbon and activated clay contained in a jumbo
cartridge (full or split size). This method only selectively
adsorbs solvent-soluble soil.
This precludes the non-ionic mineral oils
and greases from being adsorbed from the solvent, but it does
adsorb the ionic detergents, sizing, moisture and other
additives that are “friendly” to good cleaning.
The activated carbon is excellent for
adsorbing migrated dyes and extending the time for distillation
for dye removal from solvents.
Running damp cotton cloth
By wetting and extracting clean, white
cotton cloth and running them for about five to seven minutes
in the dye-infested solvent, you may remove a considerable
amount of migrated dye and a little of the other soluble soils
from the solvent; but this method is by far the least effective
when compared to activated carbon filtration and distillation.
Removal of water-soluble soil from fabrics
Load factor
Same load factor as explained in Removal
of Insoluble Soil.
Solvent level
Same solvent level as explained in Removal
of Insoluble Soil.
Distillation rate
Same distillation rate as explained in
Removal of Solvent-soluble Soil From Solvents.
Detergent
Same detergent data as explained in
Removal of Insoluble Soil.
Flow rate
Same flow rate and flushing action as
explained in Removal of Insoluble Soil.
Water
A moisture stock solution for use with the
recommended charge system should be prepared by adding one part
of spray spotter detergent, or water emulsifier, to 10 parts of
clean water and stirring into solution.
Inject this moisture stock solution into
the cylinder, after the operating solvent level has been
reached and the cylinder is placed on batch mode, at the rate
of 1Ž2 ounce per pound of fabrics (3Ž4 ounce per pound of
fabrics can be injected on special hard finish fabrics that are
excessively stained).
Solvent temperature
Solvent temperature must be between
75° F and 80° F. Solvent temperatures below 65° F
and above 85° F are ineffective and could cause damage to
dyes and fabrics.
Hot solvent will hold no moisture, and can
result in shrinkage, harshness to fabrics and dye bleed.
Cold solvent causes solvent to lose its
solvency as well as its effectiveness for soil removal.
Time
After the water stock solution has been
injected into the load, and the batch run has been for about
two minutes, the solvent will then be circulated through the
filters for a minimum of 13 minutes for perchloroethylene
solvent (15 minutes is recommended) or for 20 to 25 minutes for
petroleum/hydrocarbon solvents.
If the two-bath system is employed, then
the moisture stock solution would be injected in the second
charged bath using the same procedure as described above for
the single bath method.
I recommend that both baths be charged in
order to suspend the insoluble soil in the cylinder, but the
first bath can be charged at 0.5 percent by adding the
detergent to the load before the door is closed.
Removal of
water-soluble
soil from solvent
water-soluble
soil from solvent
Distillation
Since the anionic detergent and added
water are dissolved into the solvent to form a series of these
molecules held together by their negative charged tails being
attracted to their positive charged heads (micells), which also
contain the added moisture and staining material, we must then
remove this staining material and soils.
Distillation is the most complete method
of removing these water-soluble stains and soils.
Filtration by adsorption
The activated carbon and activated clay in
jumbo, and jumbo split, filter cartridges will adsorb a large
amount of ionic water-soluble soil and stains from solvent.
This method is next best to distillation for removal of
water-soluble soil.
Run dry cotton cloth
This method is somewhat effective in
removing water-soluble soil and stains from solvent. It is
considered as a “quick fix.”
Adding some charge detergent
This method works quickly to adsorb excess
water that has not been dissolved into the anionic detergent
and solvent solution.
This condition is indicated by a cloudy
condition visible in the sight glass. After the cloudy
condition is removed a sizeable portion of the solvent should
be distilled.
Removal of chemically-soluble soil from
fabric
Spotting board and spotting agents
Removal of this soil is by hand using a
spotting board with various spotting agents, water, steam and
solvent.
Wetcleaning
This is the alternate method of soil and
stain removal by use of water in place of solvent.
Use spotting and laundry chemicals to
remove water-soluble soil and stains in a water washing machine
or soaking vessel. Special equipment is used for washing and
drying under controlled mechanical action, humidity in drying
and temperatures.
Note: My spotting video. “The Caplan
Method of Stain Removal,” which includes my comprehensive
text (edited by Hal Horning) and the handy spotting board
reference, is available in English, Korean (video only) and
Spanish (video only) from the Golomb Group, c/o Dennis McCrory,
7664 Plaza Court, Willowbrook, IL 60521, phone (800) 679-5856.
This video is actually a “Trainer in a Box,” and is
a complete training course for both experienced and novice
spotters. My comprehensive text reinforces all of the
background technical material required to produce a
professional spotter. Each method of spot removal is thoroughly
discussed and demonstrated. Bleaching and use of digesters are
explained in addition to basic textile chemistry.
Also available from the Golomb Group, in
English and Spanish, is my video on step-by-step shirt
finishing which includes my comprehensive text in loose-leaf
form (English only) outlining each procedure for
single-operator and two-operator cabinet shirt units. Both
units are demonstrated using a cabinet sleever and single, or
triple, heated collar former. This procedure was developed by
me for top quality with no touch-up (regular sizes) together
with maximum production without overexertion by its operators.
Avoiding shrinkage, wilting and dipping of the collar, together
with its proper “breaking and forming” on the
heated collar former, are all demonstrated. Both the collar and
front buttonhole placket, the two thickest parts of the shirt,
are totally dried under the press head with no loss of
production. Attractive detailing and packaging of the hangered
shirt, padding, steam pressure and timing are all discussed. A
unique wash formula to give whiter whites, brighter colors and
complete removal of grease and body oils is included in the
loose-leaf text book.
Stan Caplan has over 35 years experience
in his own high volume dry-cleaning, laundry and tailoring
plant and two package plants with adjoining coin-operated
laundry and dry-cleaning. He is a former chief instructor at
the International Fabricare Institute, The Southwest
Drycleaners Association School, the Illinois State Fabricare
School, the Michigan Institute of Laundering and Dry-cleaning
School, the Mississippi Fabricare Association School and
Louisiana Fabricare Association School, the Pennsylvania
Drycleaners and Launderers Association School (now
Pennsylvania-Delaware Cleaners Association), the Johannesburg
Cleaners Association School (South Africa), the Hyatt-Regency
Southeast Asia School (Singapore and Hong Kong) and numerous
short courses in all areas of the fabric care industry
throughout the US and Canada. Stan offers consulting, training
and engineering services in all areas of the fabric care
industry from customer service area to the boiler room. His
total system (TQM) encompasses maximum efficiency, economy and
product excellent quality. Stan can be reached at 3601 Clarks
Lane, Suite 307, Baltimore, MD 21215, phone/fax (410) 358-0870.;
his e-mail address is:
stancap100@aol.com.
stancap100@aol.com.
