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  1. #61
    judyb's Avatar
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    Here are a couple of articles we wrote back in 2007 when this issue first hit the various forums - may make interesting reading for those seeking further information.



    pH and leather cleaning

    This is a response to several articles on leather cleaning recently posted on various forums. It has taken some time to compile as we wanted to check all our facts and needed to discuss various points with a tannery, leather technologists and our product research specialists. The views expressed below have been formed over 20 years of leather cleaning and restoration experience and with constant reference to the sources mentioned above.



    There has been reference to the IICRC S300 Leather Cleaning Method as a safe and effective guide line. This is an extremely limited over view on cleaning leather and makes no reference to problems that can be created by incorrect assessment of leather condition prior to beginning the cleaning process. There is some good advice there, but too many gaps for it to be a safe guide line with the range of finishes currently on the market. E.g. The S300 mentions the possible use of dry solvents to remove certain soils and stains. I would strongly advise against this unless you are experienced in restoration. Dry solvents (acetones etc.) will almost certainly damage finishes applied to leather surfaces which will then need repairing. To suggest that ‘application of leather conditioners to replenish natural oils’ when you are faced with a dissolved coating is very poor advice and very misleading and dangerous for inexperienced cleaners of leather.



    On some forums recently there has been much reference to the pH levels. I find this very confusing and unnecessary. In 20 years of successful cleaning and restoring leather I have never once referred to or been influenced by pH values. My advice would be to use specific leather products that have been tried and tested by your supplier who should also be willing to support you through any problems. The constant reference to pH may lead some cleaning operatives to think that pH is more important than product formulation and can therefore use any cleaner of the correct pH. Leather is NOT a fabric and cleans in a different way for which specific products have been formulated. These would have the correct pH values for the job they are designed for, you and I do not need to worry about them even if we do know them. Strong acids and strong alkalines and dry solvents all have the potential to damage leather finishes, don’t use them for cleaning, your cleaners if correctly supplied will not be of that nature.





    Spotting and problem solving in the cleaning process should be done using the same specified cleaning products but with reference to CHAT (TACT) Chemical, Heat, Agitation, Time (see separate article – to follow).



    As a general rule and particularly with pigment coated leathers you will only be cleaning the surface or finish so your cleaning process will never come into contact with the actual leather (think wiping down a painted wooden surface) so why is the pH of the leather so important. Things that cannot be resolved in this way are more likely not cleaning problems. Ink, colour loss, fading, finish cracking, permanent staining, surface abrasion, most paints, nail varnish, dye transfer, excessive soil due to body oils, inappropriate use of products etc. are damage not dirt and excessive cleaning without fully understanding the problems, the causes and the solutions is more likely to cause further damage.



    Learn what is cleaning and what is restoration and do not let the first develop into the second unless you are prepared to deal with it. It can be expensive if you can’t.



    Then we return to the ‘feeding’ ‘conditioning’, ‘nourishing’ topic.

    It is incredibly difficult to remove the ‘natural’ oils (fat liquors) from leather especially using detergent cleaners so replacing them is totally unnecessary and possibly detrimental on both finished and unfinished leathers. Modern C/T (Chrome Tanned) upholstery leather is a very sophisticated product and has been for decades. The notion that it is something straight from nature (like skin) that has to be fed and nourished is totally incorrect (unless you are dealing with conservation and restoration in the museum and antique sense). The oils and fats in C/T leather are introduced after the C/T processes have reduced the skin to pure collagen fibre (there maybe a tiny amount of fat left but it is of no significance). The fat liquoring process carefully introduces fats/oils of a specific type back into the leather to coat the fibres, These are balanced to produce the desired end product and are very stable and very difficult to remove. Trying to add more fat/oil etc is totally unnecessary and is of no benefit. On an absorbent leather, products used for ‘conditioning’ and ‘feeding’ will soak into the leather upsetting the balance and over time change it to the detriment of the leather. If the leather is non absorbent (caoted or finished as in auto leather) then these products have no where to go so will sit on the surface, getting slightly sticky and attracting more dirt. If they do manage to ‘get in through the cracks’ the results will be the same as absorbent leathers with the added problem of adversely affecting the bond between surface coatings and the leather. I thought the object was to clean it!!!!!

    LTTLtd 2007





    CHAT and the leather cleaning process



    Chemical, Heat, Agitation, Time is explained in the IICRC S300 in relation to leather and fabric cleaning and is well worth your consideration if you are cleaning leather.



    Leather should be thought of in three states:



    1. That which has never been in contact or flexed (o/s backs and o/s arms)

    2. Leather that has been subject to flexing but not much contact (borders, extreme areas of arms and back cushion and maybe some parts of seats)

    3. Those areas that are subject to body contact (this should be divided into regular direct contact with skin and those less exposed)



    Each area should be considered carefully and proposed cleaning subjected to CHAT analysis.



    CHEMICALS: because finishes on leather are difficult to chemically analyse in situ it is best to keep this simple to restrict unexpected reactions. This is why we stick to detergents formulated specifically for leather cleaning by producers with a good pedigree and labs to support testing etc.

    It does not take long to learn what sort of reaction to expect from them. Anything unusual should stop you and make you reassess. We have found that adverse effects created by tried and tested products are almost always a problem with the leather and not the product. Varying products, trying a bit of this and that will give you mixed reactions and inconsistent results. Keeping products simple means you can gauge reactions and results more accurately.



    HEAT: is a sector that cannot vary much in Leather Cleaning. Warm water for cleaning does increase the effectiveness of chemicals, but you are limited in temperature by hand cleaning processes which are more controllable then machines for leather cleaning at present.



    AGITATION; is an area with scope. But it is limited by your assessment of the stability of the surface being cleaned and strangely the dirtier the surface the more carefully it should be cleaned (heavy soiling damages surfaces so they are likely to be more sensitive to strong chemicals and heavy agitation). Do not confuse agitation with aggression. Change the type of agitation for different situations by changing the source of agitation eg: a sponge is different from a cloth, is different from a soft brush, is different from a stiff brush. Learning to clean leather is more about the type of agitation required to get the best performance out of your chemicals not the amount of power of chemicals or agitation.



    TIME: is the other area that can be used to vary your cleaning approach to varying situations. Time turns your cleaning product into a pre conditioner without having to complicate your chemical choice. Letting your product dwell is a safer approach than increasing chemical strength or pressure of agitation (extra heat is not usually an option) both of which can create unexpectedly sudden adverse reactions.



    The above look at CHAT is very brief and should be taken as a starting point. The condition of the leather surface will dictate your results much more than anything else and using CHAT analysis should help you approach it in the safest way.

    LTT2007



    Hope this helps to clarify.

  2. #62
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    Quote Originally Posted by David Fermani
    Thanks to Roger & judyB for taking the time to give us your professional knowledge and insight about the aspects of proper leather care. You’re a wealth of information. I know many people like to use what the popular people reach for, but that doesn’t mean they’re doing the right thing. I trust recommendations from people who know, not ones that have been lucky(or absent) of their results. You guys eat, breathe and sleep leather cleaning & restoration and your presence on the world’s greatest auto detail forum is greatly appreciated. It’s surprising the amount of misinformation and products that are counter productive to what we do! People need to realize that the care and preservation of leather is as important as the preservation of paint. We should be concentrating every effort on producing quality results with quality, specialized products instead of using something that isn’t intended for our field. I feel it’s a copout to advocate using a product that isn’t made for cleaning leather just because you’ve never experienced a problem with its use (yet). Like paint, you only get 1 chance to screw up. Why not use the very best approach, with the very best range of products? Thanks again! :2thumbs:


    Ain`t *that* the truth. Yeesh. :nervous2:



    Quote Originally Posted by Deanski
    Agreed, just thought that we all could use a line of products strickly for automotive leather from someone who has the knowledge and the ability to provide the right product for this task.



    Instead of everyone trying to find that "magic bullet" to fully clean and protect leather, it would be advisable to get this out to the members and to others in another forum dedicated to leather.



    This way, all aspects just as we have here for paint can be addressed and the correct product from whichever vendor. It would also serve as a way to test and maintain a professional review by those who handle leather on other products currently out now and how they apply to automotive, household or other application.



    I really think this can benefit us all on the forum here and elsewhere.



    I`m sure everyone can agree that just as in paint, there are many products to choose from and some we do not know exist, but may apply. We need to truely gauge which is the best for whaever issue we may be faced with.



    Those are my thoughs on how o better educate us and to guide us in the right direction.



    Regards,

    Deanski


    Good idea, Deanski.
    Sage advice from Greg Nichols: "Hey, Supe? When you`re trying to get the air bubble out of your syringe of Opti-Coat, don`t point it at your face, mmmkay?"

  3. #63
    STUTTGART'S FINEST Deanski's Avatar
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    Quote Originally Posted by SuperBee364
    Ain`t *that* the truth. Yeesh. :nervous2:







    Good idea, Deanski.


    I believe was can all stand to learn from those more knowledgable and experienced in the field of leather.



    Just as I was taught by one of the finest man in body paintwork over at Chinetti Ferrari in Greenwich, CT many long years ago, we can finally get the information needed to correct our bad practice on customer`s or our own leathers and learn to clean and treat correctly.



    If David B can open another thread forum just for this subject, I think it will be a hit!



    Deanski
    DR SHINE
    Swanky Shine (tm)
    What`s in YOUR garage? 997 Carrera S.

  4. #64

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    Quote Originally Posted by JuneBug
    For me - I did a test of my own on a dirty old caddie`s leather interior and woolite 8:1 worked better than all the other "leather" cleaners.


    Which is not surprising considering that a dilute woolite solution has more surfactants than most leather cleaners do. IMHO I would dilute the woolite even more, whatever the implied dilution for hand fabric washing should be ideal.



    If you think about it, woolite is intended to be used to clean silk and wool. Silk, and especially wet silk is much more delicate than leather. So woolite can be understood as a product made of surfactants which will not denature proteins nor cause them to swell when wet.



    Given that most automotive leathers are impregnated with vinyl, you are really only going to be cleaning the surface, and your cleaning solution will not be contacting the underlying leather at all.



    I didn`t have a problem wiping off any traces of woolite from the leather with just a clean damp terry cloth towel. Maybe CSI could find a trace, but I couldn`t. David - you say Woolite doesn`t recommend using their product on leather


    What matters is the underlying chemistry, not what is printed on the bottle label.



    The woolite people aren`t going to recomend woolite for an application they haven`t tested in. Which is exactly the same reason the automotive OEM`s recomend it. They have tested it and it works well.



    Remember - you can go with these chemical "experts" or believe your lying eyes - it`s up to you.


    For myself, I go with David`s approach. I ignore what the automotive OEM`s recomend in favor of what people trying to sell me boutique leather products recomend.



    Let`s face it, people who have bought hundreds of millions of dollars worth of leather for many years (and provide warranty coverage on it) have no clue whatsoever about the product or how to care for it. Supplies of boutique auto care chemicals are your only real friends.



    More seriously the stuff the chemical "experts" that David quoted sounded totally silly. For example the concern about the presence of NaOH in a product that has a pH of 7.5 in concentrated form. Or discussion about hydrogen bonding being disrupted (when what is really of concern is the fatliquoring agents being solubilized, not relavent in sealed leather) etc.



    Probably just someone trying to spread FUD about competing products while exploiting the ignorance of customers about the chemistry of cleaning products, and chemistry in general.



    http://www.autopia.org/forum/pro-det...p-not-lsp.html

  5. #65

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    I heard that Leather Masters CONDITIONER is water based and this is what im looking for. Can someone confirm this and direct me to the proper link? I see that they have a couple different conditioners and im not sure which one to go with.



    ----------------



    What is conditioning?



    For a typical modern leather seat you may find perforation and its getting closer and closer as leather tear strength increases (better quality leather has more perforation per square inch) for seating body comfort.



    So, you want to condition it!



    Do you want to condition the structure thickness averaging 1.25mm or do you want to condition the urethane coating to reduce friction from abrasion.



    Assuming it is an old car 5 years and above and you see creases and wrinkles, feel stiffer than when new too.



    There are a variety of ways to soften; often proprietary but I would explain the generic methodology practice in tannery.



    Remember leathers are grown, not manufactured with a push of a button.



    It has water and blood that past through its complex structure when the animal (bovine mainly for upholstery) is alive therefore, same as our skin it is soft, flexible with great strength.



    As the hides is hydrated it is tanned (chrome for wet-blue) follows with fatliquor to replace the water and the blood to the once upon a time living animal.



    So the fatliquor becomes the lifeblood of the leather.



    This fatliquor is hydrogen-bonded (like magnet, unlike poles attracts), ageing and heat cause the fatliquor to evaporates thus causing the collapse of these tiny millions of leather fibrils.



    That’s how you see the creases, wrinkles, micro cracks on all needle holes and perforation.





    How to introduce the original fatliquor into the leather?



    Let’s follow the simple tannery principle of fatliquoring.



    First, the leather structure has to be hydrated, to separate the inter-fibrillary spaces by using a pH 3.3 hydrator soaking it for 4 to 24 hours.



    Thereafter micro-emulsion fatliquor pH 5 (looks like fresh milk) is introduced into the structure by spraying and brushing into it.



    Again, let it dwell for 4 - 24 hours.



    What ever that does not penetrate becomes useless and to be wipe away with a acidifying rinse pH 3.0





    That’s it!



    You have re-fatliquor, replenish or re-top-up the original tanning oil - fatliquor.



    What is the total approximate quantity of tanning oil required - approximate 10% by weight of dry leather crust.





    How it works!



    A hydrator pH 3.3 or an acidifier rinse pH 3.0 charge the protein fibrils cationic (-ve) below its isoelectric point average around 4.



    The hydrator pH 3.3 opens and separates the fibrils that stick together and make way for the anionic (-ve) fatliquor pH 5.0 to coats it and hydrogen bond it.



    As it bonds, the water contents that encased the oil molecule breaks free and evaporates to the surface bringing along suspended foreign soil particulates to be wipe or erase off the surface of the leather.





    There are other Stuffing Methods that use heat to open up its pores.



    Anything that stuffs in will also leaks out when temperature changes.



    So its your choice of the various version of conditioning or rather softening and strengthening the leather!



    You have to try these various methods out, to experience first hand.



    So, next is Surface Conditioning!



    Roger Koh

    Leather Doctor

  6. #66
    judyb's Avatar
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    It is totally impossible to re - fatliquor leather once it has been through the retanning process. (Checked with many tanners over the years). The fat liquors in modern chrome tanned leathers are there to stay and the only thing that dries out is the moisture content which is why water based products are required to keep them soft and supple.



    Trying the above methods on leather that has been finished (as in the cae of auto leathers) is impossible as the fat liquors cannot penetrate the finish on the leather. It is not possible for dirt to come to the surface as suggested - all you are cleaning on leather is the surface (coated or otherwise).



    Hope this helps to clarify

  7. #67

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    More seriously the stuff the chemical "experts" that David quoted sounded totally silly. For example the concern about the presence of NaOH in a product that has a pH of 7.5 in concentrated form. Or discussion about hydrogen bonding being disrupted (when what is really of concern is the fatliquoring agents being solubilized, not relavent in sealed leather) etc





    -----------------------







    In principle pH value with alkalinity is irrelevant to sealed leather, I may agree!



    In practice, you see needle holes, perforation, cracks and wears that are where the concern lies.



    Take a leather scrap, urinate it - leave it 6 months to a year, then see what happens.



    Human urine is almost neutral averaging pH 7, Why it “reverse-tanned” the leather?





    Roger Koh

    Leather Doctor

  8. #68
    judyb's Avatar
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    Cracks and wear areas should not be `conditioned` as this will only help to further release the bond between the pigment and the leather. Finished leather that is worn or has begun to crack needs restoration work not `conditioning`



    Needle holes and perforations will allow more moisture to reach the leather itself which will keep it soft, supple and in good condition without the use of oils, waxes or `fat liquors`

  9. #69

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    It is totally impossible to re - fatliquor leather once it has been through the retanning process. (Checked with many tanners over the years). The fat liquors in modern chrome tanned leathers are there to stay and the only thing that dries out is the moisture content which is why water based products are required to keep them soft and supple.



    Trying the above methods on leather that has been finished (as in the cae of auto leathers) is impossible as the fat liquors cannot penetrate the finish on the leather. It is not possible for dirt to come to the surface as suggested - all you are cleaning on leather is the surface (coated or otherwise).



    Hope this helps to clarify




    -----------------



    In chemistry there is always the “theory” and the “practice”.





    Take a 10 years old auto seat, from a junk yard!



    Take a heat gun and heat it up, see what happen.



    Since you say only water evaporates and fatliquor stays.



    Try replacing it with water based products without any trace of tanning oil.



    It is understood that all absorbent leathers including nubuck and suede once wet and dry again, will shrink, stiff out and gradually becomes weaker.



    Any one of you experience with wet leather shoes?



    Tanning oils, raw, concentrated or emulsified as fatliquor will only soften leathers.



    Water alone won’t work because of “London Forces” also known as “Van der Waale” forces.



    Do you practice what you know, and show us that it works!



    Roger Koh

    Leather Doctor

  10. #70
    judyb's Avatar
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    Yes we do practice what we know every day. Recently we have restored a very old car interior that had dried and cracked. We applied water only over several days and this returned the leather to being very soft and supple. We then restored the pigment and the leather is now being cared for completely with water based products.



    We have only ever used water based products for cleaning and protecting and never use tanning oils etc because they are simply not necessary. Some of your principles may have some credence when talking about absorbent (aniline style leathers) but on auto leather which is almost all (there is the odd exception) finished leather which does not absorb products then they simply do not stack up.

  11. #71

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    Quote Originally Posted by judyb
    It is totally impossible to re - fatliquor leather once it has been through the retanning process. (Checked with many tanners over the years). The fat liquors in modern chrome tanned leathers are there to stay and the only thing that dries out is the moisture content which is why water based products are required to keep them soft and supple.


    IMO people get confused between the processing that is done for leather intended for fine leather goods vs automotive use vs shoes etc.



    IMHO the best way to think about leather is as a very dense non-woven fabric, with some lubricants to provide mobility for the fibers and a surface finish to protect (and in the case of automotive leather seal in) the mass of fibers and lubricants.

  12. #72

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    Quote Originally Posted by Roger Koh
    In chemistry there is always the “theory” and the “practice”.


    The theory is that vinyl coated leather doesn`t react with cleaning agents. The practice is to use a mild soap solution to clean the impervious surface.



    Take a 10 years old auto seat, from a junk yard!



    Take a heat gun and heat it up, see what happen.


    Is this the normal usage conditions for automotive leather?



    Since you say only water evaporates and fatliquor stays.



    Try replacing it with water based products without any trace of tanning oil.


    The fatliquor emulsion has broken down inside the leather matrix causing the emulsified lubricants to plate out inside the leather matrix. They are going to stay inside the leather unless you put some work into removing them.



    It is understood that all absorbent leathers including nubuck and suede once wet and dry again, will shrink, stiff out and gradually becomes weaker.


    Is automotive leather made of nubuck or suede? :ca



    Any one of you experience with wet leather shoes?



    Tanning oils, raw, concentrated or emulsified as fatliquor will only soften leathers.


    Try some PDMS, its more stable and more lubricious by far.



    Water alone won’t work because of “London Forces” also known as “Van der Waale” forces.


    Ummmm, how exactly are transient induced dipole effects important here?

  13. #73

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    >>>The theory is that vinyl coated leather doesn`t react with cleaning agents. The practice is to use a mild soap solution to clean the impervious surface



    --------------------



    In practice auto seats has orifices (needle holes and perforation) and micro cracks that absorb cleaning solution.



    Otherwise how does this work:



    “Recently we have restored a very old car interior that had dried and cracked. We applied water only over several days and this returned the leather to being very soft and supple”.



    What is mild soap solution, mildly acidic or mildly alkaline?



    When we used soap, do we collect soap scum on our basin, bathtub and show screen that attract more soiling?



    Roger Koh

    Leather Doctor

  14. #74

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    Man, this thread did nothing but confuse me more.



    How are us common folk supposed to know what to do when the experts can`t even agree.

  15. #75
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    Quote Originally Posted by Dsoto87
    Man, this thread did nothing but confuse me more.



    How are us common folk supposed to know what to do when the experts can`t even agree.


    Simple, go out and buy some Leather Masters cleaner and protection cream. I`ve used this for twenty years and it works. My 18YO MR2 leather looks like it just came out of the factory. All the rest is nonsense, IMO. I use what works for me.

 

 
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