Dye-transfer on leather, leather cleaners, and the pH issue

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Dye-transfer on leather, leather cleaners, and the pH issue

Postby jmurray2112 » Mon Aug 20, 2018 7:16 pm

I was talking today with a customer who had tried a number of leather cleaners on her off-white, finished leather sofa in order to remove dye transfer from denim clothing. She was frustrated, because nothing she tried worked.
It’s not suprising. Denim is one of the most common fabrics worn in casual clothing, and cotton by its nature is one of the least color-fast fabrics, so it’s to be expected that dye transfer would be a problem fairly quickly with leather in medium to high traffic placements.
She wanted some assurance that she wouldn’t be wasting even more money purchasing our cleaner, after trying several others to no effect. While I was explaining my experience with the difference between the ADV Leather Cleaner and most of the others I’ve tried over the years, it occurred to me that it would probably be a useful post on the forum for techs using it.
Most leather cleaners on the market out there are based on surfactants (industrial soaps). This is to be expected, because we all know soap is effective in removing soiling, light grease, and other topical contaminants that accumulate on leather surfaces. The problem with soaps though, is that they reside on the alkaline (high) side of the pH scale, at around 9-10, with water being at 7, which is considered neutral. This is a problem, because leather is tanned at around 4.5, which is in the acidic range. The pH scale is logarithmic, which means that any single digit change in either direction from neutral is ten times more either acidic or alkaline, depending on which way you are headed. As you can see, the difference between 4.5 and 9-10 is pretty dramatic. Acids and bases chemically react against each other, and the further apart they are on the pH scale, the more dramatic the reaction. Project out over years, using an alkaline cleaner on an acidic material, and the potential damage is obvious.
When we formulated our cleaner (originally known as SG-5), we had a list of attributes that we wanted. We wanted it to clean the same things surfactant cleaners did, so we added that to it. We wanted it to be effective against dye-transfer also, though, so we added a mild citrus solvent to it. We wanted it to be much nearer to the pH leather is tanned at, so we pH corrected the mixture (ADV Leather Cleaner has a pH of 5-5.5). I’ve used it for probably fifteen years now, and it really works well, better than anything else I’ve tried. I’m a technician first, and sales is not a strength of mine, but there you go. I stand by it.
Now, about dye transfer. Sticking with denim for now, because it is so ubiquitous, there is a basic way in which the dye used to color it is different from other dyes. The indigo dye used in the coloring of denim, even the synthetic version used today is insoluble in water, so a water-based cleaner isn’t going to be effective in removing it. This is an assumption on my part, but I’m guessing that denim loses its color over time not because of the soaps used to wash it, but exposure to bleach, as well as cotton’s inability to hold dyes, so a surfactant-only cleaner will also be ineffective to remove dye transfer from denim.
So, we added a citrus solvent to the cleaner, because we had experience with its effectiveness removing dye transfer on its own, and it’s my opinion that this addition elevates the effectiveness of our cleaner in this regard.

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