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View Full Version : Aniline (Sauvage) - Degreasing: How to Remove the Yellowing Effect on Aniline Leather after Degreasing?



pristine
06-25-2008, 10:35 AM
This piece collected oils from its owner. He attempted to clean it himself with a "leather cleaner". When I picked it up the areas were dark and rough. Through the cleaning process the leather reacted to precleaner and ultra cleaner by turning yellow. Most of the oils are gone but the spots remain rough and discolored. Picture 1 is the spot after precleaner...looks similar to what it did when I picked it up. Picture 2 is right after applying ultra cleaner...see it turn yellow. Picture 3 is after cleaning & rinsing. What would you suggest?
Rachelle

http://i300.photobucket.com/albums/nn4/Rogerkoh/OilspotonAniline.jpg

http://i300.photobucket.com/albums/nn4/Rogerkoh/Oilspot200012.jpg

http://i300.photobucket.com/albums/nn4/Rogerkoh/Oilspot200021.jpg

Roger Koh
06-25-2008, 01:54 PM
During the pickup it was the opportunity to educate the customer.

Customer need to understand that these dark and rough stains are just the tip of the iceberg.

What chemical reaction has taken place with “unknown leather cleaners” especially containing alkalinity will accentuate the damages.

Damages with prolong ageing will result in deterioration, color-loss, discoloration, yellowing, delaminating or cracking to surface finish.

In this case it is the texture change, discoloration or yellowing effect that has become your baby, already there unknown; camouflaged by the grease.

preCleaner aka preClean4.3™ a preconditioner only effective for cleaning heavy soiling, not good enough for degreasing.

ultraCleaner aka d’Grease4.9™ does the job what it claims, otherwise d’Oil4.4™ will never fails.

On new penetrate grease or oil it will not yellow, as I said the yellowing is cause by chemical reaction especially alkalinity through oxidation.

So we are on track!

Step 1 is to Optical Brightening Treatment with d’Yellow7.0™.

Step 2 is restoring the original color finish with anilineDye21™ and matching topcoat.

d’Yellow7.0™ pH value 7.0 when mixed with 20 parts by weight with distilled water is developed to remove yellow stains.

Leather yellow stain is the result of prolonged oil or grease hydroxylation and oxidation.

Ready to use solution contains fluorescent whitening agent that alters reflecting light waves.

These whitening agents cause a perceived "whitening" effect.

Making stains look less yellow by increasing the overall amount of blue light reflected.

Leather Types:
All leathers including – Aniline, Pure-Aniline, Semi-Aniline, Vegetable-Tanned, Pigmented, Nubuck, Suede or Woolskin.

Purpose:
To remove yellow stains associated with prolonged hydrolyze and oxidized oil or grease stains.

Preparation:
d’Grease4.9™, clean3.8™ and rinse3.0™ prior to d’Yellow7.0™.

Instruction:
Mix 1: 20 by weight with warm distilled water and shake until dissolved.

Application:
Apply evenly, agitate with appropriate brush, extract and let dry naturally.

Inspection:
Check for satisfaction when dry, repeat if necessary.

Neutralization:
When satisfied neutralize it with rinse3.0™.

Roger Koh

Leatherestore
08-13-2008, 04:45 PM
Good ideas from Roger but being new to the forum are these products specific to LD or generally available to the trade for others? We use a combination of systems and would welcome the opportunity to explore others in the continual improvement of our knowledge base. If we get to the oil "before the customer" we tend to go softly at first to see what works. Using a cleaner usually does no good on body oil but we have found a paste made from cornstarch and mineral spirits (OMS) works on all but the worst. If no luck with a couple applications of that mixture (the OMS binds the cornstarch and allows it to sit on the oil, the OMS evaporates leaving some oil in the cornstarch which is brushed off). We will resort to fumed silica (well ventilated areas only) which works well but is getting extremely expensive so not for your bargain basement low end furniture. Again you always have to plan with these to redye and topcoat as appropriate. For us these have to come back to the shop so they can sit in the updraft booth while drying. Looking forward to hearing some other ideas that have worked.

Roger Koh
08-15-2008, 01:34 PM
The degreasing you practice is by the “dry method”.

The degreasing I practice is by the “leather safe tannery wet method”.

Bear in mind the safety, health and environment aspect of the work too (fire-risk, VOC-health risk, dusty environment)

Almost in every degreasing task, fatliquor need to be replenished as we are also inevitably extracting the natural leather fats and oils too (from the original tannery fatliquoring).

So it makes sense to take the “wet” route when re-fatliquoring is mandatory thereafter.

To take the “leather safe wet route”, anionic surfactant and pH value (3 - 5) is the key to degreasing success.

The surfactant works by penetrating, lubricating and suspending the foreign grease or oil, dislodging it loose by scudding and by the natural wicking of suspended residue to the surface.

These grease or oil is considered as “stuffing” grease or oils unlike the anionic charged fatliquor which is a “hydrogen bonding” oils and fats.

Even in extreme cases for nubuck and aniline degreasing, procedure is as follows: d’Oil4.4™ &/or d’Grease4.9™ > clean3.8™ > rinse3.0™.

Rinsing at low pH (3) plays an important role in its total degreasing of stuffing foreign grease.

Also observe the pH value of the above products.

These leather safe pH values do not cause the (tanning agents, fatliquors, dyes and preservatives) to break bonds with the protein fibers.

A pH above 5, vegetable tannins agents becomes progressively free and at pH 8 to 10 they are rinsed out as brown water.

When all liquid is scudded out during rinsing fatliquor is reintroduce into the leather structure.

At this point the protein leather fibers is preconditioned below the iso-electric point to be cationic (+) charged due to the pH 3.0 rinse.

Therefore, resulting the anionic (-) fatliquor 5.0± to bond very well with the cationic (+) protein leather fibrils.

This hydrogen bonding also displace and repel the non-polar foreign grease away from the protein fibers therefore floats by the wicking process onto the surface to be brush off especially in nubuck and suede.

This explains the boring degreasing phenomenal of the “leather safe wet method”.

It can only become logical when we try it out to see the end result!

This leather safe degreasing technology principle is based on the wet operation of a standard commercial tannery.

Products are available, just email me - [email protected]

Roger Koh
Leather Doctor® System