DELICATE LEATHER CONSIDERATIONS
Some leathers are inherently aesthetically delicate. For examples calf skin, raw vegetable tanned, or full aniline unfinished leather. These delicate leathers stain and scuff easily. In some cases, the leather can be so sensitive that pure water will leave a mark. For example, simply wiping a wet rag across an unsealed veg-tanned leather to "clean" a spot may create a stain wherever moisture contacts the leather. As a professional leather repair technician, consider this problem with a client watching. Ouch! Therefore, preparation of aesthetically delicate leather requires extreme care. Like a physician, the primary goal is to NOT make the patient worse.
Also, finished leather that was once healthy but has:
1. Aged considerably,
2. Been exposed to sun,
3. Experienced heavy usage and wear,
4. Body oil accumulation,
5. Become desiccated (dried out), or
6. Been exposed to inappropriate cleaners or solvents may also present challenges.
It follows that once the finish and/or the epidermis of the hide is compromised by any of these issues, many of the leather’s characteristics, for example the moisture hold-out properties, have also been compromised.
Wherever possible test with water in an inconspicuous location to see how the leather reacts. Rapid darkening indicates that the leather will readily absorb priming agents, cleaner, finish, etc. Therefore, under such conditions, a careful touch is required not to exacerbate the problem.
Excellent adhesion of the color-coat and top-coat is a critical component for a successful repair or successful leather restoration. Without it, the repair may peel and fail prematurely, or the newly restored color coat not have quality adhesion. Good adhesion is the start of a quality repair or full restoration that will last the life of the leather. It is therefore vital to test the adhesion properties of the target leather to determine quality of adhesion to expect.
Test the degree of adhesion with the following “tape-test” procedure:
1. Scratch the surface of the leather, penetrating through any existing finish and then place a strip of masking tape over the scratched area,
2. Gently press the tape against the leather and carefully remove it. Examine the tape for any peel-up.
3. If after step 2, the tape appears normal, then using the back of a fingernail, firmly press the tape into the leather in the same area,
4. Aggressively peel the tape up.
5. If the tape does not pull up the color (you should expect small flecks to come up, but not a sheet), you’re good to go.
Caution!! Be very careful NOT to tape-test in an area of suspected pH damage that is highly visible, for example, the top surface of a seat cushion. If the leather is pH damaged, the tape-test may pull the epidermis of the hide off (de-lamination), leaving a very obvious mark. Remember, the goal is to repair the damage, not make the situation worse.
If the tape comes off very easily or doesn’t hold at all, then there is some adhesion inhibitor on, or in the leather. Keep in mind if the masking tape won’t stick, then certainly the color won’t stick either. Silicone based products that are commonly used in the automotive detailing industry will create adhesion problems (i.e. Armor-All). Pledge and other furniture polishes will do so as well. In some cases, the leather may be treated at the tannery with Teflon, silicones, butadiene rubber or some other chemical that offers nice feel related properties, but their down side is disallowing adhesion at a repair site.
Conversely, if the original (manufacturer’s) color peels up with a tape-test, then any color work applied on that base runs the risk of peel-up as well.
There are occasions when the original color appears to be peeling up when in fact the actual leather is delaminating. That is, the factory color is sticking to the outside layer, but that layer is separating away from the body of the leather. Examine the underside of the tape carefully. If there are tiny leather fibers clinging to the tape, that’s the indication that a delamination is occurring. This is a clear indication that the fundamental integrity of the leather is compromised and as such is more a candidate for panel replacement versus panel restoration. If the tape is simply removing the color, then the leather generally can be saved.