White speckles beneath the finish - Woodworking Talk - Woodworkers Forum
 
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post #1 of 8 Old 12-05-2010, 07:26 AM Thread Starter
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Question White speckles beneath the finish

The problem: In pens I have been turning white speckles appear in or beneath the finish and within the grain only , but only in dark woods like purple heart, etc. Light colored woods such as zebra wood do not display this problem.



The process is 20 some steps that include:
  1. Sand to 12,000 grit.
  2. Wipewith denatured alcohol to remove surface contaminants such as finger marks and sanding residues.
  3. Apply stand oil to bring back the color.
  4. Apply CA finishes.
  5. Wet sand to 12,000 grit.
  6. Wipe again with denatured alcohol to remove surface contaminants created by wet sanding.
  7. Apply final finish.
Before and after step 2, the grain becomes white as if filled with sanding residue, but the use of denatured alcohol does not remove the whiteness. Attempts to scrape it out has no effect. Application of a thin coat of stand oil removes the discoloration. No problems are observed until after the pieces are removed from the lathe and inspected in better light.

What is it, why does it effect only dark woods, and how is the problem solved?

Thanks muchly,
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post #2 of 8 Old 12-05-2010, 08:16 AM
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Sounds like you have done everything to remove any trace of dust. Just explain to everyone how hard it was to get that speckled look.
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post #3 of 8 Old 12-05-2010, 10:21 AM
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Sounds like you are using the same micromesh on the bare wood as you use on the CA finish. Don't! Those white specks are bits of CA embedded in the grain. I always use the sanding packs in the rolls that go to 600 grit for the wood. Any higher really doesn't help. The micromesh I use only for CA and acrylic polishing with water.
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post #4 of 8 Old 12-05-2010, 11:35 AM
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I agree with Gary, I have had the same problem and started noticing grainier woods I had to sand a litter more before the CA and some I had to sand down the CA allowing it to fill the grain then re apply. It has worked for me so far but I'm new to this.


Hey Gary, PM me you address so I can mail you that blank I promised. I'm getting them Tuesday and will send it out Wednesday. ( They lost my original order so it took longer then expected )
I'm have a bag of Pine cones now I have been getting prepped for turning. I trying them on Monday. Please include any last advise for the pine cones with your address.
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post #5 of 8 Old 12-05-2010, 07:44 PM Thread Starter
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I dunno. I think I'd agree with the CA chips if the speckles were sprinkled on the fiber surface and in the grain, but the speckles are stuck only in the grain. And I do use separate micromesh for sanding wood and for sanding AC.

I got out a good magnifying glass to get a better look, and there is more than can be seen unaided. Looks just like the white stuff in the grain before applying the stand oil. Maybe I should have used that magnifier after the oil and before the AC. I thought the stand oil was taking care of that, but it appears it isn't.

Right now I'm thinking it might be something different in the wood (purple heart) because close examination of the other pens turned in the past two weeks show none of the speckling. The purple heart was the only wood that had the white in the grain after sanding as well as after using the denatured alcohol to remove all residue and contaminants. It might be just something not removed and not saturated with the oil. But what?

It's a good thing I studied up on how to dissassemble one of these pens because that's what I'll be doing later in the week. If I don't I'll go crazy trying to figure it out by just looking and trying remember what I did when.

Any more ideas?
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post #6 of 8 Old 12-05-2010, 07:47 PM
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Hi this sounds like an oil problem.what sort of oil are you using?when i was an apprentice we would use either raw linseed or white oil to bring some depth to the colour of the wood.but if it was either put on to heavy or left on the surface for to long it would attract dust or the grit from the abrasive .i would make sure all surface oil is wiped off and the workshop isnt too cold or damp while the oil is used.
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post #7 of 8 Old 12-05-2010, 09:02 PM
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air. i always blow off my wood after sanding, about 3 times sometimes. if you put a liquid on it to clean your just making mud in the deep grain. then its really hard to get out.
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post #8 of 8 Old 12-11-2010, 05:55 AM Thread Starter
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Air was a good suggestion. Tried it on the next blank, but still got the speckles.

I use the alcohol for two reasons: it has a lower surface tension than water so "digs in" and breaks up any residues making them easier to removed, and because it evaporates quickly carrying off residues that weren't removed by wiping. Maybe using air with the alcohol will help.

Stand oil is another way of saying "boiled linseed (flax seed) oil". I use it as a base for AC's because it brings out more color and detail in the wood than just starting with the AC's. Using friction helps solidify the oil much more quickly than letting it dry at room temperature (which could take days or even weeks), and helps prevent any contaminants from being attracted or sticking to the wood. The oil I'm using is very thick, so perhaps I'll try a thinner brand of it.

I'm out of purple heart for now, so will be looking more closely at the other woods as I use them (unless someone wants to send me a couple dozen free blanks of purple heart ).

Rewiring the shop this weekend, so probably won't get do any wood working beyond boring holes in floor joists.

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