Monday 7 August 2017

Leather pigment (Colour Dye) restoration


After years of use, automotive finished leather can become worn and tired looking, and can often make an otherwise pristine interior, look old and unappealing. The option of a replacement is both expensive and very often unnecessary, and can affect the originality of your vehicle.

Leather restoration helps you or your clients add value and prestige to their vehicle, wether it is a daily driver, a Concours d’élégance entrant or a classic car. When the time comes to resell the vehicle, one with damaged leather will realise much less than one with clean undamaged upholstery so clients use renovation for commercial as well as aesthetic reasons.

As tough and durable as finished leather can be it can still suffer from wear and tear problems which can be repaired at an affordable cost compared to renewal. Finished leather upholstery is often the most costly item to replace in a vehicle. Small scale damage can be fixed with a localised repair quickly and smoothly i.e. cuts and cracks, scuffs and scratches, fading, stains, and discoloration as well as general wear and tear

Kits are available that allows you to recolor worn and faded leather relatively easily. The colour coat provided is water- based material, colour matched, that is designed to be highly compatible with leather, and provides a long lasting finish

Ensure that the pigmentation manufacturers have continued to keep pace with advances in copolymer technology and uses only the finest, first-quality pigments Prior to the removal of seat covers or renovating the pigmentation it is advisable to apply Leather Master Soft Touch (ex Vital) liberally to surfaces and then allow it to sit for 20 – 30minutes, this will soften the covers making them more workable.

Photo Degradation

[: decomposition of a compound by radiant energy]

If the interior is subjected to extreme ultra violet (UV) radiation the pigmented urethane protection will begin to exhibit a common reaction, oxidation. This is the beginning of photo degradation; a common primary reaction is an oxidation. Some materials absorb UV radiation more readily than other materials. Materials that readily absorb (UV) radiation are quickly damaged; rubber, vinyl, gel coat fibreglass, and many other plastics.

When radiation is absorbed, it starts to break (cleave) weak chemical bonds, which leads to (oxidation) photochemical degradation (bleaching, fading, discoloration, chalking, brittleness and cracking) all indications of ultra violet deterioration. The bond cleavages resulting from UV absorption cause the formation of “radicals.” Each free radical can trigger a chain of reactions (in the presence of air), leading to more bond cleavages and destruction. These oxidizing chain reactions require no further UV exposure, just the presence of air

Urethane Surface Cracks

As the leather hide loses moisture, it begins to shrink and stiffen. This leaves a minuscule 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.

Pigmentation suppliers – 
I've done extensive concourse leather restorations using Swissvax or Leather Masters products and I must say they are the best I have used compared to Zymol, Leatherequi et al

Swisswax Leather Healer Leather Dye - an easy-to-apply Leather refurbishing dye, it Is easy to apply and sets automatically and permanently, without leaving a heavy layer of pigments as often encountered with other leather tinting. The purpose of this product is to restore leather to its original colour and with a uniform matte finish, but without a "just been painted" appearance.

Apply after the thorough preparation of the leather surface; Swissvax dye sets automatically and permanently without leaving a heavy layer of pigment as it is often the case with another sprayed-on leather tinting. The leather fine and natural structure, as well as its typical original feel, are 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 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

Alternate Products
Refinish Coating - a two part system of premium coatings delivers OEM standards, using the highest-grade water-based coatings to give lasting durability, flexibility, and versatility

Leather Magic! ™ - colorants are water-based pigment restoration products used for re-colouring large areas or changing the colour of your leather completely

Leatherworld Technologies – water-based auto leather dye for most marques

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 chemicals are 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.

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 25µ (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.

The leather is correctly prepped when you start to see colour transfer from the leather onto the abrasive pad or towel. This indicates that the finish has been removed exposing the colour beneath.

Pigmentation (Colour) Renovation 
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 leather pigmentation. Swisswax Leather Refurbishing Pigmentation

Steering wheels typically have a matte clear coat to protect them from ultra violet (UV-B) light, so it’s important to replace this finish as it protects and enhances the leather and preserves its durability. Leather World Technologies Top Coat is a water-based clear coating for finished (pigmented) leather. This product provides a clear finish designed to give abrasion protection and better durability for finished leather.  

Allow the pigmentation to cure for 24 hours before the application of the clear coat. Apply with a clean lint free 100% cotton micro fibre towel, being careful to apply two thin uniform coats (allow each coat to thoroughly dry) to reduce build-up and streaks, allow to dry for 24 -36 hours; dependent upon temperature and humidity. This type of clear paint can be 'heat cured' with infra-red heat, a heat gun or a hair dryer

Finally, apply a surface a protection product Leather Masters Protection Cream with a dry micro fibre towel and allow to thoroughly dry and then lightly buff. This provides a Scotchgard™ type protection specifically formulated for leather

Note: the same methodology and products can be used on leather shift stick (gear knob) covers

Leather Stitching
If the stitching and finished leather surfaces are different colors try to avoid allowing any pigmentation to dry on the stitching; to remove wipe with a water-based solvent cleaner.

Leather stitching is usually cotton and nylon mix, nylon is attacked by harsh petroleum distillate solvents, they melt it and weaken the threads, which may cause the stitching to fail over time

Stitching is somewhat friable if subjected to excessive abrasion, bearing this in mind the cleaner needs to ‘do the work’ without relying on friction.
To renovate / clean stitching using a medium / hard horse hair brush, a toothbrush or a sponge and a safe solvent cleaner (DT-1105) this chemical is formulated from several types of alcohol and milder based solvents and it will remove all dressings, protectants, waxes, and oils from the surface. And then remove all traces of the solvent/alcohol with a foam cleaner Leather Master™ Foam Cleaner

Pigmentation (colour) Application

[: in the US pigmentation is called dye (although it’s a very different process for the application of a colorant]
 Ideal temperatures for application 70 – 75.0F with 30%-40% humidity, test the product on a small area for a colour match; it is normal that the newly applied pigmentation colour may appear more vibrant and translucent than the faded hue you have become accustomed to. If you’re satisfied with your test area, apply the product

Pour all the pigmentation into a suitable container so it can be stirred and mixed properly with a wide paint stirrer.  As some pigments are heavier than others and settle. If it is too thick, stir in a small quantity of distilled water to achieve workable consistency

 Wipe-on colour wash application - use a clean white cotton terry cloth, along with a small painting brush for small and difficult to reach areas By using the wipe on application technique you’ll be able to control the amount of pigmentation applied and don’t have to worry about overspray.

Should go without saying, use latex gloves or your hands will end up being ‘dyed’ with colorant

Using a small amount of the pigmentation,  apply to one area at a time and keep changing to a clean area of the towel, or use a fresh micro fibre towel. Being a detailer, I’m used to waxing in back-and-forth motions; however, the finish will streak with this method of application.
Thin coats (i.e. a diluted colour ‘wash’) are better than heavier applications and will produce a more natural, translucent finish. The first coat may not look great but once you have 2 or 3 coats on, then the colour will look more even. 

 Work it into the leather like you were applying a wood stain, hence the name ‘colour wash’. You use the cloth to spread the colorant around and actually work it into the leather without leaving a thick coating, since you’re working it in but not leaving much on the surface. You don't want to remove all the dye, but you also don t want to leave so much liquid dye down that it puddles in any way. It should appear almost dry when you’re done working it in

Before the pigmentation dries (seating areas) use a small foam paint roller and an artist’s soft paint brush on seams, piping, and stitching to even out colour and ensure good adhesion. If a better coverage or more colour is required apply thin coats as necessary. When the colour is correct and allow to dry for 6 hours or preferably overnight. It is normal that the newly applied colorant may appear more vibrant and translucent than the faded hue you have become accustomed to.

 Do not use an oil-based product after the application of a water-based colorant, the newer formulations of the dye will apparently be chemically altered and ruined by treating it with the oil, and your colorant will be no longer water-insoluble

Urethane Protection Clear Coat
OEM finished leather typically has a matte clear coat to provide abrasion resistance and to protect them from ultra violet (UV-B) light, so it’s important to replace this finish as it protects and enhances the leather and preserves its durability.

This clear coat (Leather Magic DT-70 Matte Finish Clear) is water- based, polyurethane compound that will provide the toughest finish over a repaired area. The clear coat may be applied either by wiping or spraying over a surface and creates a pleasing matte finish over a colour coated surface to provide substantial protection and durability

Allow the pigmentation to cure for 24 hours before the application of the clear coat. Apply with a clean lint free 100% cotton micro fibre towel, being careful to apply two thin uniform coats (allow each coat to thoroughly dry) to reduce build-up and streaks, allow to dry for 24 -36 hours; dependent upon temperature and humidity. This type of clear paint can be 'heat cured' with infra-red heat, a heat gun or a hair dryer

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