Replies

1. 
   JeffKurtz | Apr 24, 2003 01:30am | #1

   Brandon,

   Just a short article to read until John Arno jumps in here and gives some expert advice.

   http://www.wood-net.com/purpleheart.html

   Jeff

2. 
   jonsherryl | Apr 24, 2003 05:26am | #2

   Brandon, The reference Jeff has posted looks like the FPL fact sheet on purpleheart, so you now have the basic facts on this wood.

   There are about 20 species in the purpleheart genus (Peltogyne) spread all over Central and South America...so, it's relatively plentiful and affordable. It's a little coarse textured (stringy) to work with, but it's a strong and durable wood with a lot of interior and exterior applications.

   As for color, there's a lot of variation, depending upon the species and growing conditions and, for fine work (furniture), it pays to shop carefully. Some of it has light colored gum deposits in the vessel lines, which detract from it's vivid color...while the better material has dark deposits and deeper, almost violet purple pigmentation. Some of the best comes from southern Panama and usually goes by the name of nazareno, but some of the Brazilian species marketed as pau roxo are also very nice.

   The natural, long term patina of purpleheart is a warm reddish brown...and there is nothing you can do to prevent the wood from eventually developing this aged look. Varnishes containing UV blockers seem to delay the conversion of its purple pigments, but nature ultimately wins out. Personally, I think its aged brown color is actually less garish and much more attractive in furniture pieces where the wood has been used as the primary stock, but it takes a long time for it to achieve this aged look.    

1. 
   MHargrove | Apr 29, 2003 07:28am | #3

   I just bought my first plank of purpleheart to work with, likely to use in a box.  I subsequently read that PH "commonly" causes nausea.  Has anybody experienced this?  Do you need to take special precautions when working with it?

   -M.

1. 
   jonsherryl | Apr 29, 2003 10:31am | #4

   Mark, I've worked with purpleheart on several projects. Can't say as it was a pleasure, but mostly because it's just so hard and stringy. The splinters can be quite painful, but I didn't experience any unusual reaction to the wood...nor have I seen any warnings in the literature about it being exceptionally toxic. GREENheart (a member of the laurel family, Lauraceae), on the other hand, is quite toxic.

   Because virtually all woods contain extractives that might act as allergens for any person who just happens to be highly sensitive to that species' particular chemistry, it's impossible to say that any given wood is absolutely safe. But I think it's fair to say there are a lot of woods that are far more dangerous than purpleheart.  

3. 
   Marcello | Apr 29, 2003 06:37pm | #5

   BFORD,

   We specified a purple heart bench for a project I worked on.  It was a beautifull purple when it arrived on site.  After 6 months of sitting under the sun it turn into a brown color, I can't say I liked it better.  But to answer part of your question, if you keep your pieces away from the sun, they should be able to retain their color longer and the "turning" should be more gradual.  (As a general rule, they should be kept out of direct sunlight).  Like Jon said, you won't be able to stop the turning, only to slow it down.

   Jon: Have you used car wax over the finish as a UV protector on such woods?

   Marcello

1. 
   jonsherryl | Apr 30, 2003 01:21am | #6

   No Marcello, I don't do any auto maintenance and don't keep that stuff around. I'm not enough of a mechanic to even keep my tires properly inflated...But I did use UV blocker varnish on purpleheart once. Unfortunately I didn't keep the piece, so I don't know how it has faired over the past decade. I have heard from other woodworkers, though, that the UV blocking varnishes help retard the patina forming process in this wood.

   The pigment in purpleheart seems to be first created by oxidation in that, when fresh cut, this wood is a light tan in color and turns purple within a day or so. But the purple pigment, in turn, seems to be photosensitive and light, over a much longer period of time, converts it to dark reddish brown. The chemistry of purpleheart is very interesting in that when this wood is used in marine applications, it tends to turn black. I don't think it is a salt reaction, but more likely involves exposure to dissolved minerals in the water...possibly a tannin reaction.  I don't think this subject has ever been thoroughly researched though.