Purple heart colour change

[bearded bowyer]

Hi all
Just got a bit chunk of purple heart, because I have several people wanting it as a core lamination.

I took a scraper to it to see what colour the fresh wood is and its a lovely mid-dark brown.
My question is this.
If you seal the timber before the colour has changed will it still change? Is the colour change oxidation?
So......once the bow has been finished how long will the colour change take? Do I just need to put them to one side for a bit.

Please excuse my ignorance, but why does the wood change colour?

Thanks everyone
Matt

 

[Kieran Little]

If you seal the timber it seems (for me at least) to slow the rate at which it changes colour down a bit, but it will change, unless you fancy keeping the bow in a pitch black, air tight safe..

The colour change is very gradual over weeks, it will, eventually, after a great great deal of years turn to a very dark almost black colour. If you put it in sunlight it goes quicker, I have a knife handle in purpleheart that has different colours where some sat inside the sheath slightly out of the sun for years.

Mostly the colour change is caused by photochemical reactions, so the UV component of light is largely responsible. A UV blocking finish would drastically slow down the rate at which the wood changes colour but that's excessive..