judyb
New member
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.
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.
