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Questions!
09-02-2014, 02:09 PM
Can you advise me on what I need to do to repair my leather seats?
They have been re-dyed at one time.
The leather is very hard but the stitching is intact and no rips or splits

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Ltd
09-03-2014, 08:39 AM
Yes, those are mine. I'm ready to rejuvenate them

Roger Koh
09-03-2014, 11:10 AM
Besides looking good, the seating comfort does matter and a holistic leather restoration involves both the leather structure as well as the finishes.

Picture #1 shows stiff creases that accumulate soiling.
Picture #2 shows uneven distribution of suppleness where the leather flexes at the weak finishes worn lines and will eventually develops cracks.

We can conclude that it is the stiffness of the leather that causes the finishes failure with uneven stress. The main objective is to restore the leather structure suppleness so that finishes durability with equal distribution of flexing weight will be greater. Phase I will be working on the leather structure and Phase 2 on the finishing.

The sequence of processes will be as follows:

A: Wet Preparation.
A1 – Soiling contamination is removed with Degreaser-2.2 > Rinse-3.0 system.
A2 – Excess deteriorated finishes is physically removed while the leather is hydrated with Hydrator-3.3. This is a two purposes process, removing the deteriorated finishes and hydrating the leather structure at the same time. During this stage the leather becomes stronger and the finishes becomes weaker and the finishes can be easily shave off with Razor-60. Shaving does not hurt the leather crust just like our face shaving as long as the skin is damp or lathered. Sanding is only limited to removing the finishes, but often do hurt the leather grain when going too deep that makes the grain coarser. When the surface is free from foreign soiling, this wet process is continued into Hydration with Hydrator-3.3 as the main product to relax and plumps the leather structure. Unwanted finished is continuously removed during the hydration process.

B: Hydration
B1 – The leather is best kept moist all these time and during intervals plastic wrapping is recommended to control evaporation. The optimum level of hydration is when moisture ooze when press between finger and thumb. While working observed that the unnatural creases lessen and disappear, the more we work at the cross direction. Dwelling time up to 72hrs plays an important for the crushed, stick-together fiber to relax and retain original dimension.

B: Leather Rejuvenation.
When most of the creases and wrinkles are worked out and the leather plumps up. Fatliquor-5.0 takes over to replace evaporated Hydrator-3.3. With Fatliquor-5.0 the leather becomes even stronger and any stubborn unwanted finishes is work with Razor-60. Fatliquor-5.0 (an emulsion of fat, oil and water) when penetrated into the leather structures the ionic negative (-ve) fat and oil is hydrogen bond with the ionic positive (+ve) leather protein fiber and the water evaporates. The fat contents solidifies at room temperature that plumps up the leather in between the inter-fibrillary spaces, the oil lubricates each fibers like millions of interconnecting hinges that gives softness with strength to the leather and the fat and oil encased water molecule breaks free leaving behind a natural breathing spaces for leather natural transpiration. At each evaporation cycle of the water more fatliquor is replenished until the desired softness. A more specific determination is having the fatliquor moisture content read out digitally and up to 14% will be the original tannery standard.

All the hard and detail work is up to this stage the preceding stages or phases are straightforward and we shall discuss in more details when we come near after an inspection up to this stage.

C: Repairs
Where necessary repairs are as follows.
C1 – Overstretched:
Use Impregnator-26.
C2 – Leather Crust Damages Repairs:
Use Adhesor-73
C3 – Bonding Repairs:
Use Bond-3D > Bond-7A

D: Primer, Sealer & Adhesion Coating:
Use Adhesor-73

E: Color Coating:
Use Micro-54 (color matching) + Thickener-48

F: Top Coating:
Use Micro-54 Matte or Dull to match

G: Protection:
Use Protector-B+

Use this Auto Pigmented (P.a) Leather Problem Solving Guide as reference:
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Products mentioned are found in this starter Kit Ap7.cl individual refills are available.


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Leather Doctor® Kit Ap7.cl, auto pigmented (perforated) leather color refinishing kit is design for abrasion damages especially from friction rubs while getting in and out of seat. Most of these repairs may range from missing finishes to abrading damages into the leather structure. Some expose areas may be contaminated with foreign soiling that includes conditioners, protectors, body oil, grease and sweat or alkaline overexposure with all-purpose cleaners. A comprehensive repair for a long-term lasting solution will require a holistic approach to deal with both the exposed structure and surface finishes. The practical and functional softness and strength of the leather depends on the health of the structure with average thickness between 0.9 to 1.2mm from stiffness and cracking. The aesthetic aspect of the leather finishes averages 0.02mm (or 20 micron) in thickness for practical compressing and flexing from cracking. A preview of a leather-safe restoration system begins by stripping with Stripper-2.3 and rinsing with Rinse-3.0. Degreasing with Degreaser-2.2 follows with Acidifier-2.0. The suffix numbers of these four products denotes it pH value for recharging the protein fiber ionic positive besides the act of decontamination. The leather integrity is revitalized once the ionic attraction between the positive protein fiber and its negative leather constituents like the tanning agent and fatliquor (fat, oil and water) is activated. Leather rejuvenating system for softness and strength is accomplished with Hydrator-3.3 follows with Fatliquor-5.0. Structural weakness from overstretching is re-strengthened with Impregnator-26, while surface uneven absorption is sealed with Adhesor-73. These repair and auxiliary products where necessary reduces the need for color over-coating thus increase its flexibility and stretchability from premature cracking. Protector-B+ imparts a non-stick rub-resistant surface with a buttery feel, reduces noises that translate into less friction wear. As the leather surface is well lubricated it reduces compression when comes to heavy body contact thus reduces compressed creases and wrinkles.

Ltd
09-03-2014, 01:36 PM
My goal is to remove the old dye job and respray. Of course I want to clean and plump and nourish the leather prior to refinish. My question: which kit would be most suitable ? Is 2.3 stripper more or less effective than 7.7 for removing previously redyed surfaces?
Would acetone expedite the old finish removal?

Roger Koh
09-04-2014, 10:23 AM
>>> Which kit would be most suitable?

The closest most suitable kit is Kit Ap7.cl. Necessary repairs products are purchase separately as add-on. Your color is most probably a four colors combination, White, Black, Ochre and Orange, and three colors needed as add-on to the kit to match original color on your own. Option is for you to send us a color sample and the 60ml color will come as color matched - http://www.leatherdoctor.com/servlet/the-Service-%E2%80%93-Custom-Color-Matching/Categories


>>> Is Stripper-2.3 more or less effective than Prep-7.7 for removing previously redyed surfaces?

Stripper-2.3 with a pH value of 2.3 strip and protonate the leather at the same time.
Prep-7.7 removes surface contamination down to the OEM finishes with combination with Clean-3.8 > Rinse-3.0 system.


>>> Would acetone expedite the old finish removal?

Yes it would. Remember that when the leather structure is exposed with any stripper it further dries up the leather of its fatliquor and may be stiff thereafter. It has to be handle with care and proceed with Hydrator-3.3 > Fatliquor-5.0 > Hydrator-3.3 system. My choice of finishes removal especially when they are deteriorated is to avoid using any stripper. A Razor-60 works better is a weak finishes situation without the chemistry damages to the leather from denaturing. A good combination is to work during the wet preparation stage.

Roger Koh
09-06-2014, 09:53 AM
>>> Of course I want to clean and plump and nourish the leather prior to refinish.

Here is the product description and instruction fro Fatliquor-5.0. It works in conjunction with Hydrator-3.3 on an estimate ratio of 2 to 1.

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Leather Doctor® Fatliquor-5.0, a micro emulsion of fat, oil and water is an anionic charged pH 5.0 fatliquor for rejuvenating all leather types. It relaxes coarse breaks, creases and wrinkles enhance suppleness and prevent cracking. It softens the leather with stretchability, compressibility and flexibility, while enhancing its rip tensile strength greatly. It is for replenishing the original fat and oil that diminishes thru sun-bleaching, ageing, heat and alkaline overexposure or cleaning. On application, the water-encased molecule breaks free when hydrogen bond attraction takes place between the fat and oil with the protein fiber. The excess free water content wicks out leaving a breathing space behind for leather natural transpiration. The fat plumps the leather with fullness from easily collapsing into creases and wrinkles during stress or flex, while the oil lubricates the fibers so that they slide over one another smoothly like millions of inter-connecting hinges. Thus helps to keep leather at its optimum physical performance and prevent premature ageing. This universal Fatliquor-5.0 is for all leather types including pigmented, aniline, vachetta, nubuck, suede, hair-on-hide and woolskin.

Leather Approximate Quantity or Percentage of Fatliquor:

The quantities of fatliquor (fat and oil) contents retained in the leather after an universal tannery fatliquoring process may varies up to 14% depending on the leather types and it usage. This percentage drops as the fat and oil content diminishes or leaches through ageing, water, heat or chemical overexposure.

Leather rejuvenating or fatliquor replenishing is base on weight of the leather in relation to the percentage of remaining fatliquor. A simple calculation of percentage of fatliquor topping up requirement would be as follows:

If the weight of the leather in question is 100gm and fatliquor (fat and oil) content meter reading is less than 1%.

By applying 80gm of Fatliquor-5.0 to it will deliver an end result incremental of 13.3% fatliquor when dry as the 66.6% water contents evaporates.

In the leather rejuvenating Hydrator-3.3 > Fatliquor-5.0 > Hydrator-3.3 system, Hydrator-3.3 plays an important role by relaxing, opening up the inter-fibrillary spaces, facilitating and redistributing colloidal water movement, protonating and doing all the pre-conditioning work prior to fatliquoring including cleaning up any excess surface remnants to have a sticky-free surface. In practice the ratio for Hydrator-3.3 is 2 to 1 of Fatliquor-5.0.

It works out to be approximately 160gm of Hydrator-3.3 plus 80gm of Fatliquor-5.0 to replenish a 100gm dry leather from less than 1% back to the original tannery up to 14% fatliquor content.

Instruction:

1 Apply Fatliquor-5.0 and redistribute with foam brush until saturation.

2 Repeat application each time water contents evaporate until fully saturated.

3 Drive remaining surface remnants free of milky fat and oil until it turns clear with Hydrator-3.3.

4 Allow natural drying for extra softness.

Tips:

1 When crispy dry, prior surface contaminations/damages may darkens as soiling particulates resurface.

2 Removes soiling particulates with Eraser-4 for all leathers including nubuck and Eraser-5 for suede.

3 Stretching the darken areas lightly will also lightens the appearance.

Roger Koh
09-08-2014, 08:27 AM
>>>Hello Roger
This is the drivers seat cushion after 3 hours of dry time. I used laquer thinner and rags and an open 300 grit sanding pad. Comments?



Pictures to small to see surface details!



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Roger Koh
09-08-2014, 09:21 AM
>>> Larger picture.

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Picture looks overworking the grains and underworking the grooves and creases.



A good combination for efficient removal of unwanted finishes is by a stiff nylon detailing Brush-2 with Stripper-2.3.

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Leather Doctor® Stripper-2.3 is a pH 2.3 residue free hydrocarbon formulated duality leather finish stripper with bleeding control. It is use to remove existing old finishes or overspray for all leather types.

Instruction:
1. Spray, agitate with choice of horsehair Brush-1, nylon Brush-2 and or with leather Eraser-4 and extract with terry towel before it dries.
Tips:
A bristle detailing brush works into the grooves for a more thorough overall stripping unless the surface is without grain then Eraser-4 with its flat surface contact and efficient traction makes stripping much easier. Horsehair Brush-1 is recommended for all smooth leathers without heavy surface finishes safe against grain damages. A stiffer nylon Brush-2 is recommended for heavier finishes, however always test against grain damages. Leather rejuvenating with Hydrator-3.3 > Fatliquor-5.0 system is mandatory thereafter to restore the suppleness of the leather structure. Stripping by wetting the leather structure and when dry thereafter will leave the leather stiffer and should be handle with care from cracking it. Leather rejuvenating after inspection with Hydrator-3.3 > Fatliquor-5.0 system is mandatory to restore any discoloration from migrating dyestuff if any and returning the suppleness of the leather structure to as soft as you wish.


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Stripping Brush-2 is a stiff nylon detailing brush design ergonomically to be an extension of your hand with sturdy grooved grip, designed to produce effective result easily and efficiently for removing existing finishes. Length is 7 inches with a three-row black bristle 1˝ inches cleaning head.

Roger Koh
09-08-2014, 12:37 PM
>>> This is the drivers seat cushion after 3 hours of dry time. I used laquer thinner and rags and an open 300 grit sanding pad. Comments?

A sad looking leather, chemical stripping takes the life out of this leather - it looks more shrunk revealing cracks and creases as compare to original pictures posted.

Suggest the leather is rejuvenated prior to further chemical torture!


Check out the "green" or leather-safe approach to removing unwanted finishes, without squeezing out the remaining "the life of the leather" or original fatliquor here -
http://www.leathercleaningrestorationforum.com/forum/showthread.php?11821-1967-300SEL-Mercedes-Cleaning-Softening-Repairing-and-Refinishig-old-Mercedes-leather-seats