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Purple Heart Finishes

E

Emory Haselden

Joined
Dec 11, 2014
Messages
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Location
Charleston, SC
I am planning on turning some plates and bowls from purple heart, I would like to know recommended finishes that are food safe and provide UV protection to preserve color of wood.
 
UV protection. Unless one is applying paint, that's a tough one.
General finishes has an exterior water based poly that's got UV inhibitors and not merely stabilizers.
Food safe? Read the MSDS and use your judgment.
Most finish makers don't want the nightmare and cost of applying for any kind of FDA certification.
http://www.highlandwoodworking.com/woodworking-tips-1103mar/askthestaff.html
Mostly, when you want "food safe" you are out there all by yourself.
 
I am in the process of rebuilding a deck and I have been looking at the various stains to find which provided UV protection. I discovered that the clear and translucent stains do not provide UV protection. The semi-opaque stains provide some UV protection, but for total UVprotection of the wood, an opaque stain is required. I'm sure that you don't want that kind of finish.

Exterior and marine varnishes provide a small amount of UV protection but at the cost of slightly reduced transparency.and slightly greater amber color.Exterior varnishes remain slightly flexible when they are dry in order to deal with wood movement. It would be more effective to reduce the amount of UV coming in through the window
 
I may not be entirely (or at all) correct here, but I'll give a theory.

I have always thought color change in purpleheart is at least partly a function of oxidizing. When I shared a big shop with a shipwright for 10 years, I saw purpleheart change color over time that must have seen almost no UV. I've also had some kicking around home that changed color that was under cover, but that could have been also due to moisture.

Next time I see my shipwright buddy I'll ask him, as he works with thousands of board feet a year.

I'd love to hear what people think of purpleheart for turning—somewhere I read that it's a bear. A fisherman offered me a bunch of big offcuts. Based on my experience working with it on boats, and what a pain in the backside it is to work with, I figured to stick with local woods.
 
I think that you have a good point and I have also thought that that is at least part of the story. Maybe light can act as a catalyst to speed up oxidation. I do know that many species of wood are photochemically reactive. I have seen it in stacks of boards where exposed end sections turn darker than the part that isn't exposed to light.
 
Zach LaPerriere said:
I'd love to hear what people think of purpleheart for turning—somewhere I read that it's a bear. A fisherman offered me a bunch of big offcuts. Based on my experience working with it on boats, and what a pain in the backside it is to work with, I figured to stick with local woods.
Click to expand...

Zach......I did a couple of purpleheart bowls awhile back, and I remember it to be very difficult to get a clean cut with lathe tools. If I had a block of it now, I'd probably have better success, because my tool usage skills have improved since then. Regardless, I have little desire to use any more of it, because every piece I've ever seen has been very straight grain with very little aesthetic appeal......well, other than that spectacular purple color! Those turners doing laminations will probably find it more appealing as a contrasting color to their creative design.

ko
 
My granddaughter is a Purple Girl and also a budding gourmet cook, so I've made lots of treen and other small things out of purpleheart. (mostly spindle orientation) I have not found it to be a problem to turn. Yes, it's quite hard and maybe it doesn't turn as smoothly as some other quite hard woods, (think oak vs. maple) but overall, I don't consider it especially troublesome. Get some of those scraps and give it a try--then you'll know exactly how you feel about it.

Regarding color change with purpleheart, someone once told me that purpleheart responds backwards from other oxidizing to brown woods--if it starts to brown, put it in sunlight and the purple color comes BACK. I vaguely recall trying this once a few years ago. The stock I've had in my basement for several years hasn't turned, so I'm not sure I can retry the experiment, but I'll check. If boatbuilders use it, you would think they would know if it stays brown out on the deck and as topside trim. Perhaps there's not enough bright sun in Alaskan waters for that effect.

I have found that CA finish seems to retard the loss of color in other woods, such as flame box elder, but can't recall using it on any purpleheart.
 
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