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Chalk marks ?
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=50643
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Author:  cablepuller1 [ Thu May 17, 2018 2:08 pm ]
Post subject:  Chalk marks ?

Hi
Anyone had white marks in there indian rosewood grain.
I thought it was maybe chalk at first but water and methalated spirit wont remove it

Any ideas
Thanks
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Author:  bcombs510 [ Thu May 17, 2018 2:20 pm ]
Post subject:  Re: Chalk marks ?

Probably mineral deposits... viewtopic.php?f=10101&t=30651

There was a more recent thread on this that I can't find that had some solutions as well.

Author:  sdsollod [ Thu May 17, 2018 4:31 pm ]
Post subject:  Re: Chalk marks ?

As I recall, muriatic acid had been suggested. Someone also suggested lemon juice. I tried it and it worked for me...

Author:  Tim L [ Thu May 17, 2018 7:26 pm ]
Post subject:  Re: Chalk marks ?

I haven't seen that in Indian Rosewood. I have seen it in Brazilian and it was from mineral deposits. I picked it out with a hand sharpened scribe type tool and checked every so often so often with a coat of shellac to see if I got it all.

Author:  jac68984 [ Thu May 17, 2018 10:22 pm ]
Post subject:  Chalk marks ?

Looks like mineral deposits. I would ignore them until the last bit of finish sanding and, if they are still there at that point, use a dental pick and or large sewing needle to pick them out of the pores. They stick out much less under finish.


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Author:  bluescreek [ Fri May 18, 2018 5:42 am ]
Post subject:  Re: Chalk marks ?

typical of EIR and very common
I use CLR never heard of the lemon juice but will have to try it.
With CLR is use a tooth brush and then rinse with water.

Author:  Ben-Had [ Fri May 18, 2018 9:22 am ]
Post subject:  Re: Chalk marks ?

Acetone seems to work as well. It makes the natural oils in the EIR stain the deposits. Haven't tried CLR but I have some so the next time I need to I think I'll try that.

Author:  arie [ Fri May 18, 2018 10:22 am ]
Post subject:  Re: Chalk marks ?

have seen this before. trees suck up an amazing amount of stuff when they're alive. take a look at the feeder tubes of some mahogany under a microscope sometime -talk about clogged pores. ever power sanded some wood and saw sparks?

possibly calcium? or an oxide of some sort? i'm no chemist. maybe you can get it tested by a friendly lab rat who owes you a favor?

Author:  Bri [ Fri May 18, 2018 10:37 am ]
Post subject:  Re: Chalk marks ?

This is typical in quite a few woods, so predominant in Merbau that it is used an an identifier. Likely some form of silica. in some woods it can be near invisible, but this is what makes some so hard on blades and bits.

B

Author:  Terence Kennedy [ Fri May 18, 2018 2:48 pm ]
Post subject:  Re: Chalk marks ?

I have used acetone, and dilute HCL with a toothbrush. Always seems like I still have to dig a few out.

I will try CLR. The deposits appear to be a Calcium compound so they are most likely a base and one would expect an acid to dissolve them.

I asked Jim Olson once what he does and he said he usually winds up digging them out one by one with a needle.

Author:  Toonces [ Wed May 23, 2018 5:28 pm ]
Post subject:  Re: Chalk marks ?

Distilled Vinegar (not Apple Cider) works for a lot of white stuff. I also use a soft brass brush designed for cleaning wood files - works much, much better and faster than something like a needle or awl.

Author:  Eric Reid [ Sat May 26, 2018 8:00 pm ]
Post subject:  Re: Chalk marks ?

Ben-Had wrote:
Acetone seems to work as well. It makes the natural oils in the EIR stain the deposits. Haven't tried CLR but I have some so the next time I need to I think I'll try that.


Acetone should work. I know denatured alcohol (or ethanol) works. Like Ben says, those deposits in Indian rosewood are porous, and will soak up the color of the surrounding wood if you pad over the surface with a suitable solvent. Brazilian, on the other hand, has silica inclusions that behave...well. like silica. They are as hard as glass, and they absorb nothing, dissolve in nothing. (Theoretically, they should dissolve in hydrofluoric acid. I haven't tried that. I'd worry about the damage to the wood.) Pick them out, or call it character.

Author:  bobgramann [ Tue May 29, 2018 8:44 pm ]
Post subject:  Re: Chalk marks ?

If they still show after I rub a coat of shellac on, I hide them with a brown Sharpie marker.

Author:  sdsollod [ Wed May 30, 2018 8:51 am ]
Post subject:  Re: Chalk marks ?

hydrofluoric acid is bad stuff. ...dissolves bone.

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