Dictionarium polygraphicum. Tanning of Leather.

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol II.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
1735
As for the best and cheapest way of managing this affair, it ought to be that every part of the oak-tree, of what age or growth soever, and all oaken coppicewood of any age or size, being cut and procur'd in barking time, will tan all forts of leather, as well at least as bark alone; this material therefore being got in its proper season, it most be very well dry'd in the sun, and more than bark; then housed dry, and kept dry for use.

When it is to be used, the greater wood may be shaved small or cleft fit for the engine, and the smaller bruised, and cut small by the engine; which being done, it must be dry'd again very well upon a kiln, and then ground, as tanners usually do their bark.

Such wood as is to be made use of presently after it is got, will require the better and more drying upon the kiln, otherwise it will blacken and spoil all the leather.

Where oak is scarce, thorns may indifferently supply that scarcity.

Now all these ingredients will tan better than bark alooe, and that with far less charge; and by this means the selling of timber, when the sap is up, may be prevented; which wheat is done, causes the outsides of the trees to rot and grow worm-eaten; whereas, if the trees had been sell'd in winter, when the sap was down, they would have been all heart, (as it is call'd= and not subject to worms.