Examine the worn or faded spots on the urethane surface to
decide if the condition has sufficient integrity (see Repair Compound and Mechanical
Repair (Sub-patch) for renovation. Also,
any imperfections you see at this stage will be amplified after the
pigmentation. These can be removed with a light sanding using 3000 grit
finishing paper and follow with a tack cloth and final cleaning.
The urethane pigmentation
used for automobile upholstery is classified as a semi-solid permeable
membrane, being a thermosetting polymer (elastomers) it remains flexible while
retaining its tensile strength, to enable it to expand and contract, following
the temperature fluctuations (elasticity) of the substrate. The urethane
although very resilient to abrasion wear from entering and exiting the vehicle,
by using additives it still maintains its physical properties like flexibility,
tactile hand and its patina
A urethanes fibre structure
will stretch in all directions with no particular grain or stress pattern. The
urethane surface coating will not withstand multi directional stress, however,
and when it’s flexed or stretched continuously in the same place the surface
coating develops minute cracks. So any pigmentation, fillers or adhesives used
must be able to maintain this flexibility, without compromising its structural
integrity
Urethane Surface Cracks
As the leather hide loses moisture, it
begins to shrink and stiffen. This leaves a miniscule gap (delamination)
between the leather hide and the pigmented (colour) urethane coating on top of
it. The urethane coating is no longer supported by the hide; without proper
support, it starts to crack.
Colour change - if you are applying a pigmentation to change
the colour of the finished leather; surface preparation (removal of existing
pigmentation (colour) is the most important step.
Unlike lacquer-base
preparations, which close the urethane micro pores, water-base products allows
hydration (transpiration and evaporation of moisture) via the micro pores. This
enables hydration of the finished leather, maintaining its soft and supple
patina after you have renovated the pigmentation.
To bring about the best
renovation results, it is essential to prepare the leather before application. It will be necessary to remove most of the
original pigmented urethane finish without creating thin spots or sanding all
the way through the top coat. By correctly
preparing the surface and breaking down the original pigmentation, your newly
applied pigment will look like an OEM applied translucent finish.
Swissvax Leather Healer is an easy-to-apply leather pigment (dye) comprising a
high number of super fine pigments combining best results with a minimum
thickness pigment application so that
the look and feel of the leather is not affected as it is the case with many
other leather dyes. The Swissvax dye is easily applied with a small sponge and
sets automatically and permanently.
The leathers fine and
natural structure as well as its typical original feel are perfectly preserved.
46 Standard Colours are available or you can also send a small leather sample
and they will match your interiors leather colour.
Swissvax Leather Glaze- (finished leather top coating) new leather remains new for many
years thanks to the colourless protective layer provided by Leather Glaze which
drastically reduces any signs of wear. Leather driver’s seat, the smooth
leather steering wheel and the smooth leather shift knob are places where the
leather undergoes the most noticeable wear - even on new cars. That's why every
leather interior should regularly be protected with Leather Glaze for keeping
it in mint "factory" condition - an inexpensive measure and little
time invested for the best interior maintenance
Surface Preparation
A few days before commencing
the actual leather renovation, clean the finished leather surfaces. As a cleaning solution, I use a formula that
is used by one of the major tanneries to clean their leather. Mix a solution of
3% detergents that contains a surfactant (P21S Total Auto Wash) 10% isopropyl alcohol (IPA) and the balance distilled
water. And then apply Leather Master Soft
Touch (formally Vital) this is not a
conditioner per se; it softens the finished leather and make it easier to
remove the seat covers.
Like all detailing task’s the
correct surface preparation prior to the application of the pigmentation
(colour) will ensure that it adheres correctly, and has both durability and
aesthetics. Use a safe degreaser to ensure any oil and grease free surface (Leather Masters™ Leather Degreaser) this aerosol product is ideal for cleaning as it
dissolves the oils and transforms them into a powder that is more absorbent
than the leather. This powder is what is wiped off, cleaning and degreasing the
leather. Allow the white powder to dry
fully. If the powder is drying to a yellow colour, it means that there are
still a lot of oils in the leather.
And then use a safe solvent cleaner (Leather
Magic DT-152 or Leather Master Color Prep & Cleaner) these
chemical is formulated from several types of alcohol and milder based
solvents and is used primarily to prepare the surface of leather for repair or
pigmentation application. It will remove all dressings, protectants, waxes and
oils from the surface, but more importantly, it will strip off the top
most layer of the finish, which cleans
the surface so that it is receptive to the application of repair and colorant materials. This also
creates a permanent bonding of the materials to the leather.
The solvent should be sprayed
lightly over the surface, and then by using a medium soft upholstery brush will ensure any ingrained
soiling is effectively removed prior to application and to ensure proper
product adhesion. Using a cotton terry cloth
towel, immediately wipe dry. This will thoroughly remove any foreign matter
found on the surface of the leather; mild solvents also work as an excellent de
greaser. After letting the solvent dry off for a few hours the area should be
lightly sanded over, this will remove any cracks in the surface coating.
Use painter’s tape and/or masking paper around anything that
doesn’t require pigmentation applied
To
ensure adhesion lightly sand areas to be re-coloured by using an abrasive (Scotchbrite 7447 - Maroon pad, General
Purpose Hand - 320-400 grit) You’ll need to
break down approximately 25ยต (1 mil) of
the surface, this is important so the new leather dye can ‘key’ into the finished
leather and look natural. Be consistent in how far you remove the pigmentation, it is not
necessary to completely remove the pigmentation that is sitting on the leather
surface. Remove dust with a tack rag or damp micro fibre towel.
Pigmentation (colour)
[: in the US pigmentation
is called dye (although it’s a very different process for the application of a colorant]
Swissvax Leather Healer
An easy to apply pigment
(colour) that sets automatically and permanently, without leaving a heavy layer
of pigments as often encountered with other leather tinting leaving the typical
original feel of leather perfectly preserved, Certain areas of your vehicles
leather interior like seats, upholstery, side mouldings and steering wheels
inevitably start to show signs of wear, even if well taken care of, that spoil
its overall impression. Often these imperfections are not serious and are
simply colour that has worn off or light scratches in the leather surface which
can be removed and will disappear with the right application technique and our
leather dye.
Swissvax Leather Healer is
an easy-to-apply leather dye comprising a high number of super fine pigments
combining best results with a minimum thickness of the dye application so that
the look and feel of the leather is not affected as it is the case with many
other leather dyes.
The Swissvax dye is easily
applied and sets automatically and permanently. The leathers fine and natural
structure as well as its typical original feel are perfectly preserved.
Available in 45 standard colours; provide a small leather sample and Swisswax
will perfectly match the colour to your interiors leather.
Application
Spray a mist of water on the
surface and then dab a terry weave towel or a small sponge into the
pigmentation and gently rub it in, use small circular motions. Apply over one
small section at a time overlapping the circles.
Swissvax Leather Glaze (Colorless)
Developed to protect from
oxidation and embedded dirt build-up, is also recommended as a protective top
coat in exceptionally warm and/or humid climates. It provides an extra layer of
molecules over the surface protecting the surface from soiling. Use after
renovation of finished leather’s pigmentation, this clear top-coat has a
dramatic impact on leather, reducing signs of wear. The colorless, clear
protective layer provides a matte finish and protects finished leather, keeping
it looking 'as new'. It's a must-have product particularly on areas which get
the most use, such as steering wheels, leather seats and gear stick knobs.
Leather Upholstery Abrasion
(Rub) Resistance Testing
The abrasion resistance of
finished leathers thin urethane covering is designed to contend with clothing
abrasion from exiting and entering the vehicle. Wear from abrasion is a complex
phenomenon and the information Taber Industries provides at Abrasion Testing:
Taber Industries-Material Test & Measurement is meant to give you an
introductory understanding of the common wear processes and their underlying
causes. Having this practical knowledge will help to address the cost of
failures caused by wear and abrasion.
Dirt is the real enemy of
leather, acts as an abrasive every time you sit down or change your position
while driving. Abrasion wear is due to hard particles or hard protuberances
forced against and moving along a solid surface. These hard particles might be
commercial abrasives like silicon carbide and aluminium oxide, or naturally
occurring contaminates like dust particles and sand [crystalline silica
(quartz)]. If the abrasive particles are allowed to roll, rolling abrasion or
three-body abrasion occurs.
This can lead to
catastrophic wear, which is a rapidly occurring or accelerating surface damage,
deterioration, or change of shape caused by wear to such a degree that the
service life of a part is appreciably shortened or its function is destroyed.
ASTM D7255 Standard Test Method
Abrasion Resistance of
Leather (Rotary Platform, Double-Head Method) this test method covers the
determination of the abrasion resistance of leather using the rotary platform,
double-head tester (RPDH).
I would like to think that
these articles become an asset to anyone who is new to detailing and to
professionals alike, as well as industry experts who seek to advance their
knowledge.
I hope the above article was informative. By having some
understanding of the ‘What’ and ‘Why’ as well as the ‘How’ along with a little
science to help you understand how the chemicals we use react, you can achieve
the results you desire.I would appreciate it if you would share
this article as it helps other detailers further their knowledge. Questions
and/ or constructive comments are always appreciated.
Copyright © 2002 - 2012 TOGWT® (Established 1980) all
rights reserved
No comments:
Post a Comment