Purpleheart-Turning Brown

[Grant Mack]

Evening All,
I have been turning some Purpleheart lately.
When freshly cut it is the nice purple colour, after a few weeks it goes back to a brownish purple\brown colour.
Whilst appreciating that the Purple is due to oxidation of the sap when freshly cut, can anybody tell me how do I go about keeping the vivid colour?
I am using Arboroil as a sealer, cutting back with Arborwax buffing wax and finishing with Renaissance Microcrystaline wax to achieve a semi-gloss\satin finish.
Any replies are appreciated.
Regards
Grant
Perth WA
Liquid stuff fell from the sky today- am told it was rain!

[mkypenturner]

hey grant
the best way i know is to place it near a window for a while to get sunlight

[Ozkaban]

from my understanding there are several different species of purpleheart, and all are different in this regard.

In general, heat causes it to go darker brown and UV light makes it darker purple. When I finish a pen I usually hang it up in a window on a string which allows it to rotate and it goes a nice vivid purple in a few hours.

dunno why it is turning brown after a few weeks for you though, unless it's being subjected to some sort of heat (like being left in a car?)

Cheers,
Dave

[Paulphot]

Purpleheart will revert back to brown from purple with oxidation. I have a purpleheart bowl that I turrned about 2 years ago. It was a nice purple colour in blank form, then brown when I turned it. After a few hours in the sun it went purple again. I sealed it with a semi-gloss poly finish to keep as much oxygen out off the surface as possible and it is still nice and purple.

Maybe a more protective finish would help lock in the colour of your piece if you can get it back to purple. Maybe a bit of time in the sun might bring the colour back.

[Grant Mack]

Many thanks for the replies everyone.
I found links from past postings on the same subject at the foot of the thread, which were\are all very helpful.
As i mentioned I thought it might be oxidisation but my local Carba-Tech has currently got blanks now & one I bought a year ago which has been in a cupboard for over a year, which are very vivid.
And, yes, we have had some hot weather here in Perth- contributing factor- ?
I left the particular piece I had turned in bright sunlight & it did return to a "purpleish" colour.
That's what I like about woodturning- nothing is predictable & there are always new design opportunities & not mistakes
Regards
Grant