white spots driving me nuts

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BigNick73

Member
Joined
Dec 16, 2014
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66
Location
Brandon, MS
So I like turning acrylic and burl and when I finished turning there's always those little divots in the burl and some acrylic blanks I've gotten have tiny air bubbles in them. These little tiny bumps could go unseen but they seem to get packed with polishing compound in the final step and I cant figure out an efficient way to clean them out. I tried using tiny pieces of wire and mineral spirits, and it takes forever, I scratch the blank, and they don't seem to get completely clean. Though about throwing them in the ultrasonic cleaner, but that might affect the tube/blank bond. Is there anything out there that works?
 
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Small bubbles can be filled with CA.

I clean them with BLO or blow out any residue with your compressor. Once thoroughly cleaned out, fill with thin CA. It helps to use a needle to apply the CA, so it fills the hole. You might want to add some medium CA, until it sits proud of the surrounding surface. Allow to cure--at LEAST overnight. Then turn (with a skew, if you can) the proud part off to be even with the surrounding surface. Sand and finish as usual, the spot will be invisible.

Edit in: Typed while Shawn was posting---same information, different words.
 
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Patience ..... !!!! I sand the whole blank to about 800 grit. I use the point of a straight pin to remove the white stuff from the divots ... one divot at a time. After I have cleaned out one divot, I dip the point of another pin into a small puddle of thin CA and transfer a tiny droplet to the cleaned divot, sticking the pin point into the divot. I repeat this until the divot is filled with CA. I wait about 15 seconds and spray the filled divot with a little bit of accelerator. I wipe of the excess accelerator, inspect the divot and if it looks filled, I sand the area with 800 grit to smooth the surface of the divot. Then I move on to the next divot and repeat. After I have treated all the divots I can see I resand the whole blank, inspect, go over it with micromesh or finer sandpaper, and polish. It's a painstaking process but worth it in the end if you value the blank.

It is helpful to have the first pin mounted in a pin vise to give you a little leverage cleaning the divots. The second pin develops a growing blob of CA on its tip. When the blob is small it helps pick up and transfer the droplet of CA.

I took a long time typing this with interruptions. I see that two got in ahead of me. I also see that Ed recommends using a needle/pin. I don't find it necessary to allow the CA to cure as long as he says. After using the accelerator and wiping off the excess, I gently sand the divot and surrounding area.
 
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Cool I'll have to try the needle thing for applying the CA. I tried just dropping it from the bottle that that makes a little more work than I like, smoothing it back out. I actually have some watch oilers that may just serve that purpose well.

I did take a old toothbrush and some soapy water to the piece of acrylic I just turned and found it cleaned them out pretty well. Not sure why the last few I got have so many tiny air bubbles in them, though they all came from the same place. I'll have to buy some BLO and try it as well.
 
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