Bruce, it's true that the majority of turnings don't involve dyes, stains or other coloration alteration outside of the effect of the oils in varnishes, but that's not universal. Consider Jack Vessery's work...all those amazing pieces are made from cherry, but his burning/carving/coloration techniques show zero wood in the end. He uses cherry for it's working properties, not it's color. Chris Pitik (sp?) uses dye to great wonder. Art Liesterman's pieces are instantly recognizable, no matter what the form, because of his coloration techniques. Same for many others.
For furniture and cabinetry, coloration might be avoided for some species, such as cherry, yet embraced for other speices or styles. In some cases, coloration techniques are used to balance and make uniform the tone of a piece...the work folks put into mahogany pieces, such as many in the Newport style, fits into this catagory. The example above of the figured maple piece shows how coloration via dyes can greatly enhance the figure of the wood to bring out a particular effect. In fact, the same wood with different colors or dye regimens (application...sanding back...application, etc.) can provide a great variety of effect while still being very much "wood".
So I basically leave cherry alone. (That's almost a religion for me!) Either dye or not dye figured maple. Dye poplar 99% of the time. Use oil and shellac to bring out the honey tones in black walnut that will be there once it oxidizes and gets naturally lighter. Etc. Very project and species specific.
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The most expensive tool is the one you buy "cheaply" and often...