This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
We know enough of the confusion arising in collections through the loss of labels, when, from want of timely renewal, they decay at bottom. During the past year I set my wits to work to find out a better plan of charring them to render them durable, and, from present experience, I believe I have hit upon a good plan. Before detailing my own way I will just mention that the plan pursued previously, and which I was taught while in a London nursery, was to dip them in melted lead; this did not answer very well, and was often inconvenient. The way I have hit upon is, to my belief, original, and is as follows: Having made the labels, before they are painted get a dish or vessel of any size and suitable depth, say four inches deep, which fill with turpentine. In this you may dip the labels, a handful at a time, immersing them as deep as required, and then take them one by one and apply a light to the point, this will char them well superficially, if properly done, and much more neatly than any other plan I have seen.
When so charred they appear to be very durable. - Jaques.