A bit of background on the panels: in another life they formed a screen, but it appears the leather was cut from something originally larger (possibly wall paneling in a room, or an even larger screen). This is suggested by the sharp cut lines along the edges and the fact that part of the painted/embossed border design has been trimmed. The wood frames to which they are now attached appear to be relatively recent. Narrow strips of leather secured with brass nails were added to cover up the cut edges.
Each of the four panels is comprised of two sections of leather stretched over a wooden frame. The leather is embossed and painted with floral and animal/bird motifs. The surface is varnished overall and stained to give the painted background an “antiqued” appearance.
Current condition: The leather is extremely desiccated and brittle, and shows an advanced stage of a type of deterioration known as red rot. The latter includes overall loss of strength, embrittlement, desiccation, and associated cracking, flaking, and powdering of the leather with resulting breakage and loss of fibers—this is particularly apparent in the leather trim along the edges.
This is what red rot looks like up close:
You can see that the fibers are breaking up and crumbling to dust.
The problem, simply stated, is that the leather is disintegrating. The fibrous structure made up by the collagen protein is literally breaking apart and turning into dust, especially in the trim leather, which is of a different type than the large pictorial areas. The trim is extremely ragged in appearance due to the abundance of losses. There are a number of tears and splits in the primary decorative leather as well, the worst of which is across the bottom of panel #1 (below). To complicate matters, the varnish on the main leather (but not the trim) is sensitive to many solvents, including alcohols; it is not adversely affected by naphtha or xylene.
A comprehensive discussion of the mechanisms of leather deterioration can be found in Conservation of Leather and Related Materials by Marion Kite and Roy Thomson. I highly recommend this book for anyone that is working with leather.
Oh, I should mention that the backs of the panels have been lined with a layer of acidic paper and a heavy woven cotton fabric. Both are adhered with animal glue! Ugh!! Oddly enough, the fabric does not extend all the way to the edges of the frame, and looks as though it was applied after the leather was stretched onto the frame! Not a well thought-out solution, and clearly not the work of a professional conservator, nor even that of a skilled restorer.
Removing the lining is not really an option because the leather is too weak and the damage this process would likely cause is too great (plus, our dear client has limited funds). Therefore, we will only be removing certain sections, where it’s necessary to gain access to the back for mending tears and splits.
Coming up next: Treatment highlights