Sadly, leather afflicted with red rot can never be brought back to its original healthy state again. The weakening and embrittlement are irreversible. All the more, it is essential to consolidate the powdery leather to strengthen it before undertaking any tear repairs, otherwise the repairs simply won’t hold and the leather will crumble apart. Our solution to the problem is described below.
Consolidation: For the trim leather, I found it best to use a combination of consolidants, taking advantage of each of their favorable properties. Not having enough Pliantex to treat all four panels, I am reserving it for the cracks and splits in the varnished main sections of leather that are sensitive to alcohol.
The following system evolved from my mock-up trials for consolidating the trim, and is working really well so far: I brush-apply (fairly liberally) two consecutive coats of 1% Klucel in ethanol—it easily penetrates and almost immediately disappears into the leather; this is followed by an application of 2% Klucel; and finally, an application of the Klucel/SC6000 mix (equal parts of SC6000, 2% Klucel in ethanol, and ethanol) which mostly seems to sit on the surface and seal it. The latter adds strength, seals the surface, and dries to a nice sheen that is in keeping with the original finish. To get the solution underneath the lifted bits and edges of the trim, a small syringe works better than a brush.
For the main painted/varnished areas, Pliantex will be used exclusively, as it is the only material that seems to work (hoping that we don’t run out before the end of the project).
Keep in mind that all of this is just part of the preparation for lining tears and securing loose bits of the fragmentary trim. Without consolidation, it would be impossible to adhere anything to the powdery leather, since it would just flake or peel off almost immediately.
Incidentally, I did some preliminary tests on a scrap piece of leather (flesh side) consolidated with various dilute adhesives, then adhered strips of non-woven polyester to it with BEVA 371 film by heat-setting. When I qualitatively tested the peel strength of the Beva/fabric, I was surprised that the leather fibers broke and gave way on all the samples except for Pliantex. The strip was nearly impossible to peel off the sample consolidated with Pliantex since the leather fibers would not break. This tells me that it’s superior in strength to the other agents of consolidation commonly used for powdery leather.
Here is what an area of the border looks like after consolidation. The color of the leather has darkened somewhat due to saturation, which is inevitable, but it has gained significantly in strength and flexibility.
Compare to the same area before consolidation.
By the way, does anyone know why Pliantex was discontinued? If someone has found a source or reasonably good substitute for Pliantex, please, please let me know!
I will be adding more info as the treatment progresses. Next up will be reinforcing the loose fragments along the edges, and then later on I’ll discuss the process of lining tears and splits.