Replies

1. 
   Kell | Jan 24, 2003 11:53pm | #1

   Don't know about yellowheart but purpleheart, for me at least, never seems to keep the initial purple color.  I've tried poly, danish oil and lacquer to no avail.  Is it just because it changes when hit by UV rays?  It always ends up a dark brownish purple.

   Kell

1. 
   drumdino | Jan 25, 2003 07:57pm | #2

   thanks, kell.  what about a spar varnish with a u-v blocker?  and would that take over oil to boost the color and pop the grain?

2. 
   jonsherryl | Jan 25, 2003 08:08pm | #3

   Kell, I'm not real sure on this, in that I suspect the patina forming process in purpleheart is rather complex...But it seems to me that the initial purple pigmentation is triggered by oxidation (or by other atmospheric gases), while the long term browning results from the photosensitivity of these first generation pigments.

   When purpleheart is first cut it has a light tan color, but within hours the purple pigments begin to form, even in the dim light under a tropical forest canopy (and even over night with the lights off in my windowless basement shop.)

   Nothing will indefinitely preserve the purple color, but UV blocking varnish does seem to slow the process down.

   Another complexity of purpleheart's pigmentation is that when this species (actually there are about 20 species in the purpleheart genus; Peltogyne, and not all of them qualify as prestigeous cabinet woods) is used for marine pilings, it turns jet black...So, one of its extractives must also react to something in the water, either the salt or perhaps a dissolved mineral (akin to the tannin-iron reaction in bog oak.)

   Wood pigmentation and the patina forming process still rank right up there among wood tech's greatest mysteries.

2. 
   dirtstirrer | Jan 25, 2003 11:39pm | #4

     I wonder if any of you can anwer the same question about aromatic red ceder?  Is its dulling due to UV's or a harder to counteract process?  If there is a way to keep it vibrant I'd sure like to know it.  Thanks,

                            Steve