"Hawthorn doesn't have sapwood and heartwood; it's all white throughout and could be considered a whitewood. Since it is diffuse porous, it is nearly impossible to ring chase. Whatever you do, keep the wood directly underneath the bark unharmed! Split, remove the bark and make sure the wood remains intact to function as the back of the bow."
Where has this idea come from? It's not the first time I've heard this. All woods have a heartwood and sapwood. Some have bigger ones than others, some don't get heartwood untill their over 10" in diamter. Bowyers are the only people that use the term whitewood and heartwood, and it isn't entirely correct.
This statement requires some clarification.
I agree that the term 'whitewood' is very vague, and only used by bowyers. I wonder who came up with the term? I don't like the term either, since there seems to be no exact definition, but we use the term so often, we get accustomed to it.
The term 'heartwood' (as well as sapwood) are used globally and are well accepted with clear definitions.
I agree that all woods contain both sapwood and heartwood. I should have said "Hawthorn doesn't have
visually distinct sapwood and heartwood". It does have both sapwood and heartwood, but we cannot distinguisih the two visually. The color is the same throughout the log and we would need a microscope to see the difference between the living sapwood and the dead heartwood. The confusion starts with the phenomenon "
false heartwood". I would strongly invite you to google that term. It is widely used in wood trade and is distinctly different to heartwood. Hawthorn (as well as ash, hickory, beech, poplar and willow) has false heartwood. The color of this false heartwood does not overlap with the occurence of the actual heartwood. False heartwood is always heartwood, but not all heartwood of a log is transformed to false heartwood. The latter is often deteriorated to some degree by fungus, rot or deposition of certain substances.
I quote this piece of scientific literature, which very nicely describes the way it works.
The wood quality of different broadleaf species is defined according to their “natural” properties
including the color of the wood. Mostly, the wood color is uniform from the pith to the cambium.
However, for individuals, parts of the wood extending from the pith can be dark (red, brown, grey or
black). Darkly colored wood is normal in some species [e.g., elm (Ulmus sp.); oak (Quercus sp.);
sweet chestnut (Castania sativa L.); black walnut (Juglans regia L.)] and not classified as false
heartwood. Wood discoloration has been reported for some broadleaved species: poplars [4], beech,
(Fagus sylvatica L.) [5], wild cherry (Prunus avium L.) [6], paper birch (Betula papyrifera Marsh.) [7],
silver birch (Betula pendula Roth) [8] and ash (Fraxinus excelsior L.) [9].
(Reference: "Frequency of False Heartwood of Stems of Poplar Growing on Farmland in Sweden", Tord Johansson and Birger Hjelm)
I hope this removes some of the confusion. For us bowyers, this may not be too relevant, but still interesting. All we need to know, is that false heartwood is generally undesirable in bows, while heartwood is generally better than sapwood. But not all species produces false heartwood, nor can we predict (before cutting the tree) how big the false heartwood will be.