How to get purpleheart gidgee colouring back?

Hello, I am in big trouble, and need your help please!

My eldest daughter has a beautiful piece of purpleheart gidgee bought from up Maleny way. It is about 400 x 100 overall, with bark on the long outer edges. One side is totally deep purple, and the other is deep purple in the centre of the opposite side, in an elliptical shape that followed the elliptical shaped grain on that side. The other grain outside the ellse was greyish -yellow, presumably sapwood.

Tje board had some cracks and a wide end split, so I glued a small 4mm thick floating tenon into the end and across the largest end check, then filled this crack with epoxy toned with black and light purple on the all purple side. Turned out beautifully, can barely see the large crack after it was sanded.

Then turned it over to the other side, and filled the other side of the large crack with some cedar coloured TimberMate, which turned out reasonably well too against the sapwood colouring, although a bit on the lightish side. Did some other thin cracks the same way on that side.

In readiness for oiling this bare timber, and getting rid of what looked like thicknesser chatter marks on the whole surface, I put it through the drum sander. After one pass each side, DISASTER!! Not only were there long scores in the timber from the sander, half the deep purple colour disappeared on both sides, so much so I thought my daughter had been conned and had bought a piece of stained timber. The drum sander used well worn 60 grit, snd these long scratch marks would not come out with 100 grit paper on the ROS.

I am in deep trouble. Can I please get some suggestions on removing these long scratches, and on restoring the deep purple colour if possible?

Joe, if Purpleheart 'Gidgee' is similar to normal Purpleheart, the colour will return after some time in the air. I've been working with Purpleheart a bit lately and went through the same worry the first time I machined the surface.

Not sure about the scratching. ROS? I have a roll of 240g that I use on my drum sander when necessary to remove scratches, but have to be careful because the finer paper heats up a lot.

Good luck with it. :fingerscrossed:

It will go purple if you expose it to sunlight.

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Originally Posted by chrisb691

It will go purple if you expose it to sunlight.

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Even indirect UV seems to work fine, though maybe a little slower - mine was in the shade and still coloured back up in less than a day.

This is sounding very hopeful, thanks for your replies. Actually, it looks much better today than what it did at 4pm yesterday, so have put it out in the sun, turning it over frequently in case the heat of the severe tropical sun caused more cracks to appear. In the end I put it next to the pool under the shade of the shade cloth.. here's hoping.

My next main problem is removing the scratches from the drum sander. Any suggestions please? I have included some pics below:

Attachment 335345
Underside side of the board. The outer deep purple colour was fairly uniform throughout this coloured area of the board originally.


Attachment 335349

Top side of the board. You can see the scratches from the drum sander here. I put the board at an angle to the drum :(
100grit on a ROS will not remove them



Attachment 335347
This shows the 4mm Domino tenon that will stop the large crack from expanding. Filled with epoxy mixed with black powder


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Top side showing 3 long thin cracks filled with Timbermate - could not quite match the colour of the timber



Attachment 335346

Scratches more noticeable here


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Scratches at the other end of the top surface


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Underside of the board, originally deep purple

All I can think of is sanding, sanding, sanding.

The only thing that will do it is cutting back below the scratches, one way or another.

How quickly can you get your hands on a finer grit, (or grits), for the drum sander? After 60g, and those scratches, ideally 100g, then 150/180, followed by 240 on the ROS would do it. (Each grit about 1.5 times the previous one.)

Sorry I can't be of more help. Chris or someone else might have a better idea.

Edit: You could try a freshly-burred cabinet scraper if you have one. Might be a slow process, but it would leave a nice surface.

I find, too, that passing timber through the drum sander many times. without lowering the drum between passes, will clean it up a reasonable amount.

Thanks Steve, yes, lots of sanding seems to be the answer, but am worried the purple colour will disappear again. Will soon find out :-

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Originally Posted by Dengue

Thanks Steve, yes, lots of sanding seems to be the answer, but am worried the purple colour will disappear again. Will soon find out :-

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The purple WILL disappear again with sanding, but will come back with uv exposure. :D

:whs:

Sounds like you're on top of it now, Joe. :2tsup:
You'll have to show it to us in the finished piece when done. I love that heartwood/sapwood contrast.

I agree the purple will return after a little while.

One thing to note when working with purple heart do not finish it straight after sanding.

Many thanks to all you guys for your help and support, feeling a lot more confident in dealing with this amazing timber - never heard of a timber whose colour restores after sanding by UV exposure. Will post pics of the finished board :2tsup::2tsup:

Will also try scraping, but it is pretty tough timber, so not very hopeful

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Originally Posted by Dengue

Will also try scraping, but it is pretty tough timber, so not very hopeful

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The tougher the timber the better it scrapes.
Do you have a scraper plane?

Thanks Tt, that is great news. I have a Veritas cabinet scraper because of arthritic thumb joints, so will tune up a couple of blades and give it a go - looking forward to this, but will wait a few more days until the colour is fully restored by sunlight ( not quite direct, too severe)

Well, my first go at serious scraping - it was great, with very fine long shavings straight off the new blade fitted to the cabinet scraper. They looked so beautiful I posted photos of them twice below :)

The Veritas scraper blades have a 45 degree bevel, but the instruction book that came with it recommended that you don't need to burnish and create a hook initially as it would be too aggressive.

The scratch marks have disappeared, and the scraped purple surface was glass smooth. Took care to scrape with the grain, starting in the centre, and not to do too much. Most of the scraping was done pulling the blade towards me from the centre, as I had toggle clamped the far end of the board.

The remaining scratch marks are actually full length minute hairline cracks that first showed up when I wet the board with White Spirits. Will wet the board again tomorrow and show some pics - not sure how to finish with these cracks.

Will then leave this board out under the patio to get some fresh air and light, ocassionally putting it out in direct sunlight for a few days to get the deep colouring back.

Thanks for the scraping suggestion. The scraper was a group birthday pressy from the kids last March, but have not had the need to use it, and had actually forgotten about it.

Attachment 335510



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Love these shavings - beautiful colour



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You can see the large epoxied crack on the right


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Close up of the scraped surface



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Shavings again :)