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Clogged/White Pits in Walnut and Purple Heart

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Forum topic by Shaun posted 11-20-2017 02:29 AM 2017 views 0 times favorited 11 replies Add to Favorites Watch
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Shaun

39 posts in 852 days


11-20-2017 02:29 AM

Topic tags/keywords: question walnut purpleheart padauk lathe turning finishing

Hi Everyone

I’ve been pen turning for the last 5 months or so. I think I’m doing fairly well with it. But I’m having trouble with wood that has ‘pits’ in it. I’m not sure if ‘pits’ is the right word but I think it illustrates the idea.

Walnut, paduk and purple heart all give me this grief.

Once I’m done sanding, fine dust is in the pits. Or, at least, it looks like fine dust. There are little white specs. In the case of purple heart, they are more like long channels rather than small pits.

I’ve tried cleaning it up with de-natured alcohol. I had what I thought was good success with this tonight. It cleaned up a beautiful walnut crotch pen and I looked very closely. All of the Pits seemed cleared. Then I finished it with 9 coats of BLO + CA. Finally, I used plastic polish. Same technique as I use for all other pens with good results.

To my great annoyance, many of the pits are white.

I’m not sure if it’s sanding dust or something to do with how I apply finish.

Any insight would be greatly appreciated.

Thanks, everyone.

-- Shaun, Ontario, Total n00b at wood turning


11 replies so far

View Lazyman's profile (online now)

Lazyman

3570 posts in 1810 days


#1 posted 11-20-2017 03:25 AM

I don’t really understand why some people use BLO with the CA. The CA by itself seems to work just fine for me. My last project posting was a turned walnut and maple shift knob finished with CA (my first walnut turning) and I did not see the problem you are describing.

Is it possible that your BLO is really one that has polyurethane in it and it is not working well with the friction because it hasn’t cured yet and it is accumulating in the deep grain of the wood? I’ve had a similar problem when I tried to scuff sand a coat of poly on a project before it was cured and it sort of gummed up. I think that I would finish one without the BLO and see if that makes a difference.

Also, the surface has to be completely smooth or the plastic polish will get trapped in any pores or deep grain which shows as white. I have been able to clean it off with a little bit of water and a paper towel but that may depend upon the brand you are using? For deep grained or large pored wood, you may need to try using a grain filler, though I have never tried that with a CA finish.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Ripper70

1292 posts in 1331 days


#2 posted 11-20-2017 03:29 AM

Perhaps using an air compressor and blowing the dust away would work. A few good, high pressure blasts may do the trick.

-- "You know, I'm such a great driver, it's incomprehensible that they took my license away." --Vince Ricardo

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Woodknack

12845 posts in 2803 days


#3 posted 11-20-2017 04:28 AM

Walnut and paduak are somewhat coarse grained so I suspect you are talking about the wood pores? I’ve never used purple heart. I think what you are seeing is sanding dust in the wood grain, a blast of air or a toothbrush will remove it. I’ve never heard of using BLO + CA so I don’t know if that could cause a problem. It could be moisture or air trapped under the finish. If you are putting on BLO, which would fill the pores, then putting on CA glue and later the BLO is absorbed into the wood leaving pockets of air under the CA, that could cause those spots. Try it without BLO.

-- Rick M, http://thewoodknack.blogspot.com/

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Aj2

2321 posts in 2220 days


#4 posted 11-20-2017 04:49 AM

Were you eating a powdered donut at some time during the finish? I don’t know what else it could be. :)

-- Aj

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Lazyman

3570 posts in 1810 days


#5 posted 11-20-2017 01:19 PM

I too think it is the BLO. Even if it is not one with a poly or varnish in it as is very common, the BLO needs to be cured before you put a top coat on it. That can be accelerated somewhat using friction during the application on the lathe but my theory is that any that accumulates in the pores is not going to to be cured as well and probably just be gummy and the CA finish just locks it into the pores in that state of ugliness. I would try the CA without BLO If you want the grain darkening effect of the BLO, you could also try applying the BLO and then waiting for it to fully cure before applying the CA.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View Jack Lewis's profile

Jack Lewis

456 posts in 1501 days


#6 posted 11-25-2017 02:53 PM

Have you considered wet sanding with BLO or beeswax and mineral oil? This would not only fill the pores with oil but also solidifies when cured. It also cuts down on free dust in the air, lubricates the wood and keeps it cooler, conserves the sandpaper and doesn’t clog the grit. NOT my idea but I use it often. It helps to pinpoint any minor imperfections that need to be addressed before final finish.

-- "PLUMBER'S BUTT! Get over it, everybody has one"

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johnstoneb

3117 posts in 2595 days


#7 posted 11-25-2017 03:20 PM

Walnut, paduak and purple heart are all slightly open grained wood. You are getting sanding dust in these pore and not getting it out before applying the finish. Try using compressed air to blow off the project before applying the finish. Then try the wet sanding recommended above.

-- Bruce, Boise, ID

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Shaun

39 posts in 852 days


#8 posted 11-25-2017 04:35 PM

Hi Everyone

That’s fantastic information. It sounds like there are 4 possible culprits being suggested:

- Dust in the pores that must be removed with compressed air or a toothbrush
- The plastic polish getting trapped in the pores because the CA finish follows the contour of the pits
- A reaction with the BLO
- Eating powdered doughnuts while turning :-)

I don’t have an air compressor at the moment but will hopefully be getting one shortly. In the mean time, I’m going to grab a soft toothbrush from the dollar store. Maybe that will help.

A few have mentioned that I shouldn’t use BLO and CA. I find that CA alone takes forever to cure. I use thin CA and it can take 10 to 20 minutes per coat. If I use BLO and CA, it sets up in 2 minutes. Maybe my technique with plain CA is bad?

Jack – you mentioned wet sanding with BLO. Would I just use the regular wet sandpaper I would use for sanding with water? How about micro-mesh? I usually dry sand half-way through the micro-mesh grits on a pen before applying finish. Would I wet-sand with BLO was well? And then, do I wait for it to cure and then put on the CA finish?

Thanks, everyone. I’ve got some things I’m going to try this weekend.

-- Shaun, Ontario, Total n00b at wood turning

View Jack Lewis's profile

Jack Lewis

456 posts in 1501 days


#9 posted 11-25-2017 05:08 PM


Jack – you mentioned wet sanding with BLO. Would I just use the regular wet sandpaper I would use for sanding with water? How about micro-mesh? I usually dry sand half-way through the micro-mesh grits on a pen before applying finish. Would I wet-sand with BLO was well? And then, do I wait for it to cure and then put on the CA finish?

Thanks, everyone. I ve got some things I m going to try this weekend.

- Shaun

I sand with Klingspor cloth backed economy boxed roll ends. Then wipe the piece down AFTER each grit before adding any final finish. The sand paper lasts forever if wiped down also. I don’t wait very long, a day or two, for BLO to cure. Seems the friction of sanding heats it up some and cures faster. It sure brings out the final appearance of the piece too.

-- "PLUMBER'S BUTT! Get over it, everybody has one"

View Lazyman's profile (online now)

Lazyman

3570 posts in 1810 days


#10 posted 11-25-2017 05:36 PM

I use Stick Fast thin CA when I finish with CA. I give it a short blast with their accelerator and it’s ready to sand for the next coat in less than a minute. When I applied the finish on these beer mugs, I completed the multiple layers on each mug in less than 20-30 minutes including sanding between coats going through both the satin and gloss polishing compounds. The walnut and maple shift knob easily took less than 10 minutes from beginning to end to apply and polish 7 or 8 coats. I got a little bit of ridge on it that I didn’t notice until I was finished that I think was caused by trying to use a medium thickness on the first coat. It didn’t go on smoothly and sanded it back to wood but I must have missed a spot.

BTW, I use Abranet mesh sandpaper because it doesn’t clog as easily. When it looks like it is starting to clog, I just flick it with my finger and it is clear again.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Shaun

39 posts in 852 days


#11 posted 12-16-2017 07:28 PM

Hi All

It has been a very busy 3 or 4 weeks. Lots of time at work and my weekends mostly eaten up.

CA with accelerator is life-changing! That might sound dramatic but I have so little time to turn I need to make the most of it. I can do a coat in under a minute and it’s HARD!

I never understood the advice on sanding between coats because whenever I did I would almost immediately sand through the CA. Not any more. I can slap on a nice, juicy coat of thin CA, give it the tiniest shot of accelerator and in 45 seconds it’s rock hard.

No more BLO for me!

I’ve also been using a toothbrush to clean out the pores and it works REALLY well. I still haven’t gotten an air compressor.

You guys really helped me a lot. I’m trying to make some darts for a friend out of thuya (cedar) burl. It has LOTS of small voids. The voids are interesting but kept getting filled with sanding dust and I couldn’t fill them enough with CA.

Now, I sand it up to 2000, use the toothbrush to clean out the voids, clean it with DNA and put on about 5 to 10 layers of thin CA with accelerator. Then, sand it 400 through 2000 and use plastic polish. It works so incredibly well. It shines like I’ve NEVER seen.

What amazes me is how well the thin CA + accelerator works at filling the voids. I don’t even have to worry about them any more. Just put on several coats and 10 minutes later it’s perfect.

The other thing that shocked me is how THICK the layers of CA are. I kept hearing people talk about building up 3 or 4 thousands of an inch of CA. I could NEVER do that. Now, with just 3 or 4 coats, I’ve added at least a couple thou.

Life-changing. Absolutely life-changing.

Thank you, everyone! Your advice is so appreciated.

PS:

Lazyman – I’m also using StickFast CA and accelerator. That’s what my local woodturning store carries, although they are the only one in Canada that does. Nice big bottles for cheap and it works well!

-- Shaun, Ontario, Total n00b at wood turning

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