PurpleHeart

Bill J

Bill
User
I have worked with purpleheart quite a bit but and have tried a number of finishing methods. The "common wisdom" has been that purpleheart will darken to a plum color when finished but using UV resistant poly can slow the change. I recently got a couple of really nice dark boards and am once again perplexed. The attached picture shows a cutting board and a pencil holder made from the same board! As you can see, the board is plum colored and the pencil holder a nice dark purple. I saw the same phenomenon with another board (not shown) that retained the nice purple color. All three were finished with a mineral oil/beeswax mixture. The only difference I can think of is the time that elapsed between planing/sanding and finishing. The darker ones sat for a few weeks and the plum color I finished the day after sanding.

Has anyone else seen this?
Thanks
Bill

PS: the board is a cafe wall optical illusion, the lines are straight but appear to curve. The pencil holder has a couple of small magnets countersunk into the back. I have found this is a great use for small cutoffs.
2020-12-03 11.05.09.jpg
 

Oka

Casey
Corporate Member
Purple heart will always fade eventually. Oxidation and uv are the culprits. If you use uv rated varnish and seal all 4 sides completely ...and avoid direct sun it will last several years. But, my experience is it fades to brown are plumish brownish eventually (7-10 years)
 
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Jeff

New User
Jeff
You can't stop it no matter what you do or how you finish it. It's like cherry darkening with age.
 

Bill J

Bill
User
I guess I should have been clearer; I know it will eventually darken. What I noticed was the immediate change to one piece while the other has retained its color for over 6 months. I'd like to delay the inevitable for as long as possible.
 

Jeff

New User
Jeff
I guess I should have been clearer; I know it will eventually darken. What I noticed was the immediate change to one piece while the other has retained its color for over 6 months. I'd like to delay the inevitable for as long as possible.
Thanks. I have no idea why the color changed so rapidly in sections of the same board almost at the same time. I don't know what causes the color in purpleheart but whatever it is maybe there are different concentrations of it in different sections of your board. ?????
 

drw

Donn
Corporate Member
I really do not know the answer to the question, but I will speculate that the color change relates to oxidative changes that we observe in various foods (bananas, apples, shrimp, etc) which darken due to oxidative reactions. These changes can be inhibited with antioxidants (e.g., ascorbic acid [vitamin C]) which is often used to retard oxidative changes on fruits. I suppose the changes observed on purpleheart may be similar. The addition of mineral oil/beeswax could be acting as a barrier to oxygen exposure thus retarding the color change. Again, this is just speculation.
 

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