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Maximizing the Purple in Purpleheart?

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Forum topic by JohnMcClure posted 04-10-2019 11:50 AM 631 views 0 times favorited 7 replies Add to Favorites Watch
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JohnMcClure

710 posts in 1153 days


04-10-2019 11:50 AM

How do I get the best and longest-lasting purple color with purpleheart?
Purpleheart is brown when freshly cut; according to the wood database, a few days of “exposure” turns it purple; applying finish also brings out the purple; then over long periods of UV exposure it becomes a deep brown.

Three questions, first: the initial Exposure – is this oxygen, UV, or both? Do I need to set my boards out in the sun?
Second: if I put finish on after a fresh cut, without this exposure, will it stay brown or will the finish bring out the purple?
Third: Is a UV-resistant finish like spar urethane sufficient to maintain the purple (indoor furniture) for several years?

Thanks all.

-- I'd rather be a hammer than a nail


7 replies so far

View CaptainKlutz's profile

CaptainKlutz

1898 posts in 2007 days


#1 posted 04-10-2019 12:13 PM

Answers are available here:
https://www.wood-database.com/purpleheart/

Color/Appearance: When freshly cut the heartwood of Purpleheart is a dull grayish/purplish brown. Upon exposure the wood becomes a deeper eggplant purple. With further age and exposure to UV light, the wood becomes a dark brown with a hint of purple. This color-shift can be slowed and minimized by using a UV inhibiting finish on the wood.

Sunshine has high levels of UV light. Can also get UV from black light, but much lower levels. Only way to stop purple to black fade is keep wood in dark room. :-)

Might like this too:
https://www.wood-database.com/wood-articles/preventing-color-changes-in-exotic-woods/

Best Luck.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View Dave Polaschek's profile

Dave Polaschek

4158 posts in 1095 days


#2 posted 04-10-2019 12:28 PM

That second article that CptKlutz pointed to is what I was going to reference, too.

Also see Shipwright’s blog series on colorfastness

-- Dave - Santa Fe

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JohnMcClure

710 posts in 1153 days


#3 posted 04-10-2019 01:30 PM

Thanks all. I had seen the first article, but what I’m trying to get at is how to accellerate the onset of “intermediate color” portion. Has anyone tried putting purpleheart in the sun, unfinished, then finishing with UV inhibiting finish?

-- I'd rather be a hammer than a nail

View RichBolduc's profile

RichBolduc

1119 posts in 629 days


#4 posted 04-10-2019 01:45 PM

I’ve also heard of people using a heat gun to get the purple back on top of setting it in the sun.

Rich

View Bob5103's profile

Bob5103

147 posts in 1346 days


#5 posted 04-10-2019 03:47 PM

Purpleheart reacts to UV and heat. I use purpleheart for accents, small turnings, boxes, etc. To speed up the process you can use a heat gun, stick in the kitchen oven at 300* for about 30 minutes, (with permission from the boss), when turning small pieces like pens I use a small Bernzomatic butane torch to bring the color back. There are obvious risks to doing this. Here is an excellent article on purpleheart, http://hobbithouseinc.com/personal/woodpics/purpleheart.htm.

View CaptainKlutz's profile

CaptainKlutz

1898 posts in 2007 days


#6 posted 04-10-2019 03:59 PM


Thanks all. I had seen the first article, but what I m trying to get at is how to accellerate the onset of “intermediate color” portion. Has anyone tried putting purpleheart in the sun, unfinished, then finishing with UV inhibiting finish?

- JohnMcClure

My results don’t agree with Wood Finders website time line?
Suggest it depends where you live, and sun/UV index?

Here is AZ, can cut Amaranth in the morning, set grey wood on a table outside shop for a few hours, and by lunch time it’s light purple. Takes couple hours longer in winter. Have to make sure I rotate the boards every few hours or color gets radically different between sides.
Left a piece outside for two weeks, and it was faded/beached brown.
Similar to results from Shipwright’s testing posted above.

Best Luck.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View SMP's profile

SMP

1401 posts in 418 days


#7 posted 04-10-2019 04:05 PM

It would be interesting to see a sample done with purpleheart like this guy did with cherry. Notice the huge difference on finish used even though same stick of wood same time in the sun.

http://www.woodweb.com/knowledge_base/Darkening_Cherry_to_Match_Existing.html

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