Recent Certified Lab Results: (07/2020)
Sulfur Content: Below detectable limits
(Approximately 6.5 ft/each, full substance>1.2 mm or shaved to .8 mm)
As a leather vendor, I get to speak with people in the bookbinding and conservation field all the time . (Member of Royal Society of Chemists, certified expert witness in field of leather for Thomson Reuters, member AIC)
In the early 1800’s bookbinding leather which was produced after ca 1800-1830 had a shorter lifespan than leather produced in earlier years. The time period, 1800-1830, coincidentally marks the beginning of the modernization of the tanning industry with the introduction of machinery and new chemical tanning techniques
The late 1800’s saw the first formal survey of leather bound books throughout England in rural and urban libraries. The observations from these surveys yielded a plethora of information.
At the turn of the 20th century, a group of British scientists met to create guidelines for producing superior bookbinding leather . They used the observations of these previous surveys and established a guide line of leather tanning/processing criteria be used for future bookbinding leather.
Several decades later, new library surveys were conducted to ascertain the condition of bookbindings and the leather which had been used for their manufacture. There was no significant improvement in longevity. Manufacturing standards were not recorded nor was there accountability that the original British standards were followed. As little of the leather produced according to the standards stood up to the test of time, two possibilities are apparent: Either the leather was not produced according to the new standards OR the new standards were not correct to guarantee longevity.
Additional information on this subject can be found in “Leather for Libraries”, Hulme, Parker, Jones, Davenport, Williamson, published for the Sound Leather Committee of the Library Association, 1905.
Our vegetable tanned (native tanned) Sokoto goatskin leather is produced using historical bio-chemicals and no other substances which would question its archival properties. Our “time enduring” skins are not pickled prior to tanning and no sulfur containing products are used in any processes including the unhairing process, such as sodium sulfide or sulfuric acid. The literature indicates that leather in the processes of tanning has a great affinity for sulfur (Betty Haines) which ultimately yields another decomposition route for bookbinding leather. Our Native Tanned Sokoto and the Native Dyed version of this item contain no sulfur bearing compounds such as syntans, sulfonated fat liquors, sulfuric acid, sodium sulfide, etc. They are tanned with a gentle pyrogallol tanning agent, bagaruwa. The “time enduring” version is never exposed to any metal e.g. for manipulating the grain, shaving, etc. Skins are sold unshaved at full substance.
Our Native Tanned Native Dyed (NTNDTM) in traditional Red, dyed with local biologicals, is only produced in Sokoto Nigeria, using the centuries old formula.
We have affidavits as evidence from reputable institutions in Sokoto, Nigeria that have verified the leather which we offer as Native Tanned Natural and NTNDTM to be of the same grain pattern and most likely the same formula that was used over 200 years ago. To the best of our knowledge, there is no other commercially available vegetable tanned goatskin which can claim historical/archaeological evidence of longevity.
Our Sokoto goat which is colored in Nigeria, is claimed by Bernard Middleton to be the same leather used in the Stonyhurst gospel book which was taken from the tomb of Saint Cuthbert, is over a thousand years old. The book is the oldest known surviving intact book in Europe and was bought by the British Library in 2012 for £9 million pounds as part of a fundraising campaign.
Per Bernard Middleton p117 A History of English Craft Bookbinding techniques:
“That which covers the Stonyhurst Gospel is dark red and is similar to modern native dyed Niger”
We are the only purveyor of leather made with these sulfide free formulations.
“The Trans Saharan Book Trade”, by Lydon, states that the only source for the color “Traditional Red” in NTNDTM can only be produced in Sokoto, Nigeria because of the presence of unique biologicals. This is further evidence that Spanish cordovan leather and perhaps the leather used in the Stonyhurst Gospel are NTNDTM Sokoto goatskins