Factors Causing "Crocking" of Leather Furniture Finishes
Crocking is when the finish begins to thin or separate and start showing the leather underneath. The affect can be from a spider-web like appearance to actual peeling of the finish. The affected area has a very worn look to it when this condition occurs.
1. Thickness of the original leather - Full thickness cowhide when properly tanned will give 30 years of useful service on furniture. If the hide is split so that it is half as thick, it will give from 10-15 years of useful service as furniture depending on the amount of wear it gets. When it's split to a third of the original thickness, it will give from 5-10 years of useful service as furniture depending on the wear.
2. Grade of leather - How well was the leather tanned? This is usually felt by the softness of the leather. The softer the leather the less finish has been put on it to protect it because it's been tanned better. On a pure aniline sofa, it's been tanned the very best and consequently no stain resistant finish coating has been applied to the leather. On leather of a lower grade the tanning isn't as good and more finish coating is applied to the leather to protect it; however, this finish is more prone to "crock" the more of it there is on the leather.
3. Elasticity of the leather - What area of the cow is the affected leather from? Leather nearer the belly of the cow has more stretch than higher up on the back. Usually, furniture manufacturers use leather from higher on the back to make seat bottom cushions since it will resist stretching; but, sometimes they are running short and cut corners and use a panel from lower down on the cow than they should. Premature finish wear results.
4. Excessive wear, pet and human body oils - If the furniture is used extensively, wear of the finish can result. Pet and human body oils also have a debilitating affect on leather finishes over time and can begin to cause "crocking" especially on armrests near where the hands rest, on the headrest area, and on the seats where shorts do not cover the legs.
5. Lack of maintenance - Finished leather furniture needs to be cleaned and conditioned with a leather cleaner and conditioner every six months. This helps remove undesirable body oils and conditions the finish to help offset the dryness which occurs to the finish from the atmosphere and from wear. Removing harmful oils and dirt with a pH balanced leather cleaner/conditioner protects the pH value at which the leather was tanned. If the pH value of the leather is allowed to change through use of wrong cleaning agents or not cleaning/conditioning at all, the leather will begin to crock and deteriorate to the point of tearing or developing holes. There is no way to fix the pH value of leather once it changes. Refinishing it makes it look better but does not solve the problem.
Leather which is "crocking" can be refinished to remedy the problem; however, the problem may reoccur due to the above factors. There is no way to tell how long a refinishing job will last in these areas.
