Dark spots on blanks when finishing

[Stugots]

Happy Easter all,

I don't know if this has been brought up or not so I apologize in advance if it has. I just turned a nice blank from purpleheart for a cigar pen and when I polished it it appears to have some debris from the sanding process in the natural cuts and grooves in the wood and it is giving those spots a blackish look. Is this normal with this type of wood or am I doing something wrong when I am finished sanding. After sanding I wipe the blanks down with some denatured alcohol to clean it up as much as I can and after doing that the blanks look good. I was also wondering if the polish I am using is creating the dark spots. Not a huge deal and I kinda like the look but if I am doing something wrong can somebody give me a pointer or two?

Thanks

Tony

 

[Mark]

I believe the answer is yes and yes. You could be getting some debris from the bushings when sanding over them. Yes, I have had polish turn black on the bushings and then contaminate the wood grain. It has happened with many different species of wood. Mostly lighter woods where it is very easily seen.

The solution I use is applying polish with my finger tip and buffing it off from the center of the turning, out. That way I'm not carrying the black off the bushing over my work. Delrin bushings would likely remove the black altogether, but I haven't purchased any of those yet...

Just my $.02 worth. Happy Easter.

 

[Fibonacci]

Another possibility is heat. Purpleheart changes color with heat. I have had a couple pieces that developed dark spots from cutting too fast and getting a localized area hot enough to turn it dark enough purple to appear black in my shop lights.

Out in the sun, they generally turn out to be deep purple, but not always.