National Clothesline
Surface spotting using abrasives
The first prespotting technique to be used on suedes before drycleaning or
wetcleaning is surface spotting or abrasive spotting.
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Caution: Never use any of those abrasive spotting tools on leathers! Use
abrasive spotting tools only on suedes!
Surface spotting with the abrasive strip
The first tool for surface spotting we will consider is the abrasive strip. It
is a medium grit carbide emery cloth that comes in rolls or sheets. Rolls are
easier to work with since they don’t have to be cut up into strips to make usable pieces. The pieces of abrasive
needed can easily be torn off of the end of the roll by hand.
The emery material with its cloth backing is far more durable than sandpaper.
The medium grit will normally allow good soil removal with minimum risk of
damage to the suede.
The abrasive strip can be used for surface spotting any type of suede.
The piece of abrasive strip can be used on any suede at the spotting board or
spotting table to scrape off any crusty spots, stains, soil, oxidation marks or
ink marks that are found on the surface of the suede. Surface crusty spots
include soil, food, blood, ink, paint, nail polish and glue on the surface of
the suede.
The abrasive strip may be gripped between the thumb and the forefinger and
pressure should be exerted on the cloth side of the strip by either the thumb
or the forefinger or the forefinger and middle finger together.
The amount of pressure applied should vary with the type of skin being spotted.
Use light pressure on the more delicate lambskin and sheepskin suedes. Use
heavier pressure for tougher cowhide and pigskin suedes.
The abrasive side of the strip is placed in contact with the surface of the
suede wherever there is a crusty surface stain, spot or ink mark. The abrasive
strip is rapidly drawn across the spot several times from every direction until
the crust of the spot or ink mark is scraped off. Scrape less on lambskin and
sheepskin suedes. Scrape more on cowhide and pigskin suedes.
Some of the suede nap may be removed by this process. This will not be a problem
as there is plenty of nap and it will not be missed.
The area scraped may look lighter in color after the rusty spot, stain soil,
oxidation or ink mark is scraped off. This in not a problem. The light color
will disappear in the cleaning or after cleaning by the hand spraying the suede
with a special leather neutral spray.
Care should always be exercised when using the abrasive strip on soft, delicate
or weak skins to avoid damaging the surface. Any residue of a stain left in the
skin after the surface crust has been abraded and removed is an indication that
the staining material has also soaked into the skin in addition to leaving a
residual surface crust or ink mark.
In such cases, the remaining spot or stain will have to be removed by spotting
with a special leather liquid spot remover after the abrasive spotting is
completed.
The best way to prevent liquids from soaking into suede or leather is to
pretreat the skin with a special suede and leather liquid repellent protective
coating that will resist the penetration of liquids into the skin.
Ideally the special leather repellent will not change the color or feel of the
suede or leather. Please do not use repellents made for use on cloth items as
they are likely to make the suede or leather color darker and cause the skin to
become stiff and the nap to become coarse and matted.
Once the special leather protective coating is applied to a suede or leather,
any liquids that spill on the suede or leather item will roll off of the
surface. Any of the spilled liquid that remains on the surface will bead up
instead of soaking into the skin.
The spilled liquid beads can then be blotted up from the surface. If any liquid
residues go unnoticed and dry they can be brushed off with a special suede
brush or scraped off the surface with the abrasive strip so that no residue
will remain.
Surface cleaning with the abrasive block
The abrasive block is a spotting tool that can be used to surface spot and
rapidly remove crusty spots, stains, soil, oxidation and ink marks from cowhide
and pigskin suedes only.
Do not use it on delicate sheepskin or lambskin suedes.
This abrasive tool has the advantage of rapidly removing crusty spots and
stains. However, it is always used only on cowhide and pigskin suedes as they
are tough enough to withstand the highly abrasive action of the abrasive block.
Caution: Never use the abrasive block on any smooth leather. It is for use only
on tough cowhide and pigskin suedes!
The abrasive block is very abrasive with a porous inconsistency and is very hard
with sharp edges. It is black in color. It is man-made, formed into blocks of
various sizes that can readily be hand held to scrape the surface of cowhide
and pigskin suedes at the spotting board or spotting table.
The abrasive block resembles volcanic rock and lava rock. It also releases a
sulfur odor of rotten eggs when used in a way that wears it down and exposes
its inner structure.
In leather cleaning, this occurs when pressure is exerted on the block as it is
scraped across a crusty spot or stain on the surface of a cowhide or pigskin
suede. Hence the term “stinkstone.”
In drycleaning, it is also referred to as “lava rock,” “volcanic rock” or “pilling stone” when it is commonly used to remove pills from sweaters.
Surface spotting tough cowhide and pigskin suedes can be done faster using the
abrasive block.
To use the abrasive block, grasp it firmly with the thumb and forefinger. Rub
the end of the block across the crusty surface spot or stain in all directions
while applying pressure on the block with the hand. The pressure can be varied
to suit the spot being removed.
On most cowhide and pigskin suedes, there is no limit on how much pressure can
be applied. However, excessive pressure will cause rapid disintegration of the
block at the point of contact with the skin. When that happens you will know
that you have used too much pressure. Too much pressure will only damage the
abrasive block and leave a gritty residue. It will not normally damage a
healthy cowhide or pigskin suede.
As in all things, use common sense. There are some cowhide and pigskin suedes
that contain panels that come from unhealthy animals and from belly skins.
These skins may be weak and thin with a ragged nap. Use the abrasive block or
the abrasive strip on these skins with care and with light pressure to avoid
damage.
On healthy cowhide and pigskin suedes, the abrasive block will remove some of
the suede nap from the skin surface along with the crusty spot or stain
material.
This is not a problem. Most of the nap will remain unless excessive or
unnecessary abrasion is done in a local area. Pigskin suedes have a very short
nap and will not lose as much suede nap when a crusty spot or stain is abraded.
However, even with a pigskin, avoid excessive and unnecessary abrasion when
surface spotting.
Remember, you are trying to remove only the surface of the crusty spots and
stains, not the residue of the stain that has soaked down into the skin. To
attempt to remove the residue of the stain by abrasion will eventually make a
hole in the skin.
The residue of the stain that remains in the skin after surface spotting with
the abrasives, should be removed only with specially formulated safe leather
liquid stain removers on the spotting board and soil release additives in the
cleaning machine.
Surface spotting with the steel wool pad
Another abrasive spotting tool that may be used to surface spot suedes to remove
crusty spots, stains and ink marks is the steel wool pad. This abrasive tool
has the advantage of being less abrasive and less likely to cut into the
surface of the skin.
The pad also has the disadvantage of leaving a lot of steel wool shavings all
over the suede on which it is used. These steel shavings can oxidize and rust
if left on the surface of the suede after it is spotted with a leather wet side
prespotter.
In addition, the person using the steel wool pad can get steel splinters in his
or her fingers.
Steel wool shavings also accumulate around and on the spotting board and require
frequent clean-up. The steel wool shavings can also get into the cleaning
machine, its pump and its filters. These shavings are the result of the
breakdown of the steel strands in the steel wool pad. Since the pad breaks down
rather rapidly, the quantity of pads used can be significant.
Surface spotting of suedes can be accomplished by using the steel wool pad.
The steel wool pad is used in much the same way as the abrasive strip and the
abrasive block previously described. The steel wool pad is held between the
thumb and the other four fingers. The pad is than drawn across the surface of
the stained suede several times, from all directions, first in one direction,
then in another until the surface crust and stains are removed.
Some surface suede nap will be removed along with the stained material. The
amount of suede nap removed will increase with the grade of the steel wool pad.
The coarser the pad, the more nap will be removed when the pad is rubbed across
the suede. As in the case of the abrasive strip and the abrasive block, the
small amount of nap removed from the surface of the suede will never be missed.
Steel wool pads come in a variety of grades from very fine to coarse. The
typical grades of steel wool pads are as follows:
1. Super fine grade numbers 0000 and 000. These pads are for an extra-smooth
effect on suedes. This grade is good for removing crusty spots and stains from
very soft and delicate suedes such as lambskin and doeskin.
2. Very fine grade number 00. This pad is used in the same way as grades 0000 and
000, but it is used on skins that are a little less delicate, such as soft
sheepskin and deerskin suedes.
3. Fine grade number 0. This pad provides a step up in abrasiveness and can be used
on soft calfskin suedes and mature sheepskin suedes.
4. Medium grade number 1. This grade may be used to remove crusty spots and stains
from the softer cowhide and pigskin suedes.
5. Medium coarse grade number 2. This grade should be used to remove crusty spots
and stains from cowhide and pigskin suedes.
6. Coarse grade number 3. This grade is used only on mature cowhide and pigskin
suedes that are excessively soiled and badly stained.
Surface spotting with the sand blaster
The sand blaster is an abrasive spotting tool that provides mechanical muscle
for high-volume production surface spotting as in a high volume wholesale
leather cleaning plant. The sand blaster propels abrasive particles with
compressed air through the nozzle of a gun into the surface being spotted.
There are several different types of abrasives commonly used in sand blasting.
The use of sand blasting to remove crusty spots and stains from suedes is an
adaptation of a technique originally developed for cleaning metal, concrete,
brick, plastic and stone and for frosting glass as well as removing surface
finishes from wood.
Sand blasting of suedes must be done with great care by an experienced operator
to avoid damaging the sueded skin.
If sand blasting is done by an inexperienced operator, the suede can quickly
have a hole blown through it where the spot was located. If the operator is
semi-experienced, the suede can be quickly worn down to the equivalent of five
or ten years of normal wearing. If the operator is experienced, the crusty spot
or stain can be removed quickly and efficiently with no damage to the suede.
The big drawback to sand blasting is that some of the abrasive particles cling
to the suedes and come loose in the cleaning machine where they enter the
cleaning fluid pump. There they abrade the pump impeller and cause the
unwelcome and frequent maintenance to replace pump impellers.
In addition, the abrasive particles manage to enter the pistons of air operated
presses and cut up their o-rings and cup seals. This creates additional
unwanted maintenance.
The investment in equipment required to perform sand blasting on suedes includes
the following: air compressor; sand blast gun; an air hose and couplings; blast
cabinet; pressure regulator; moisture regulator; proper sandblasting abrasive;
abrasive reclaimer; and a dust collector.
A suction-type sand blaster is appropriate for use on suedes. It delivers only
one-fourth the velocity and impact of the pressure blaster, so it is less
likely to damage the suede in the hands of an experienced operator.
The item being sand blasted is placed inside a cabinet for operator comfort and
efficiency. The work is illuminated by internal lighting and can be observed
through a safety glass window.
The operator reaches into the cabinet by inserting both hands and arms through
two armholes in the front of the cabinet. Protective gloves built into the
armholes protect the hands and arms of the operator and prevent any of the
abrasive particles and dust from escaping the confines of the cabinet through
the armholes.
The abrasive reclaimer draws the abrasive out of the cabinet. Dust and debris
from the suede are removed from the abrasive and are conveyed to the dust
collection system. A removable debris screen traps the suede lint prior to
dropping the reusable abrasive into the storage section. A feed system measures
the amount of abrasive fed to the blast gun.
The dust collection unit allows continuous cleaning of exhausted air by the use
of cloth filters. Dust is collected in a dust drawer.
The abrasive that is most applicable for suedes is a by-product of agricultural
products. These abrasives are soft, slow cutting and specifically designed for
use on soft surfaces. They include walnut shells, crushed fruit pits, ground
corn cobs, ground rice hulls, etc.
For faster action, manufactured abrasives like aluminum oxide or silicon carbide
can be used. Natural abrasives like sand are not commonly used.
