dirty sapwood

[Peter Hawkins]

Hi everyone, hope your all fine and well,
My query is when doing natural edge bowls etc, when ever I do mesquite natural edges the yellow sapwood all ways tends to appear dirty and grubby (not worms) if the wood is wet or dry the same result, but probably slightly worse when wet, and primarily the end grain is far worse. It spoils a reasonable product in its overall appearance.

Please can anyone help me with this problem.

Regards , Peter

 

[MichaelMouse]

Only thing I can suggest is fast and blast. Don't have mesquite, but leaving cherry in the log allows the sapwood to soak up some of the extractives that color the heart, blurring the contrast. Sooner I get them turned, the whiter they stay.

I have taken George's recommendation to blast the excess unbound moisture out of the piece with compressed air. Speeds things through the mildew zone enough to keep from developing black spots.

Other recommendation is don't sand the sucker wet. That'll carry darker, extractive-laden wood dust into the sapwood areas, even embedding them if you press. Blast, let dry a couple-three days, then sand.

 

[Martin Braun]

Hmm... I've done some natural edge pieces with mesquite, and haven't noticed a difference between that and non-natural edge. Is it only happening when you do natural edge? If you have a picture or two, maybe those could spur some additional ideas.

MM is right in that if you leave it sit for longer before you turn, the tannins have a tendency to migrate from the heartwood into the sapwood and create a black 'layer' at the interface of heart & sapwood. However, I think it looks beautiful. It happened with some logs I stored outside in the shade (no room in the garage at the time). If the 'dirty' appearance doesn't happen on your non-natural edge bowls, then it may be something else.

 

[Martin Braun]

Well the issue you mentioned has been stuck in my brain all day. The only thing that I can think of, is maybe you're getting some dirt/bark from the natural edge smudging your sapwood. So maybe it's a matter of really cleaning the bark well with a pressure washer or such.

Another idea - before you make your final pass, maybe try to seal up the wood with light shellac, or another option might be Sherwan Williams sanding sealer. Either would dry pretty fast, and potentially help keep the surface clean as you make a final, very light cut or scrape.

Robert Rosand recommends the SW treatment before making the final pass on his small hollow forms & such to help with tear-out or punkiness. I've never tried it for that, but I do like it for a quick, light finish on small pieces.

 

[MichaelMouse]

Bark or bast dust can be scrubbed right into the pores wet or dry, just as the heartwood dust can. I avoid that problem pretty well by attempting to solve another, that of customers breaking off the bark. Use of CA not only firms the bark for errant fingers, it works as a sealer. Blast before you treat if you try sanding sealers that you rub or brush, rather than flow on.

Other thing that occurs to me is the possibility that Pete might be using an oil finish and muddying/discoloring the waters a bit. Don't know.

 

[Peter Hawkins]

Thank you Michael, Martin,
I guess I was contributing to the problem with the Mesquite, ....I tended to soak the bark from the top with a laquer/thinners mix, this could of caused migration of colour from the bark, plus I tended to turn the wood before it was properly dry, and sand too, I will play around with both of your suggstions, with the other natural edge woods I have used it was not a problem just the mesquite, and boy do we have an abundance of that here.

Thank you again gentlemen for your advice which will be used, regards from a newby to turning,

Regards, peter