Ebonite spots

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bg15

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Hey guys,

I have been fiddling with Nikko ebonite for some time and I always get different results while finishing it. To be more exact - I cannot get ebonite to be pitch black and besides that, there are black spots visible under strong light.
My method of finishing is wet sanding from 320 - to 12000 micromesh + Buffing. I know ebonite hates the heat, that is why I use a lot of water when shaping it and sanding.
Have you ever seen this kind of spot on your ebonite?
 

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I have not seen those kind of spots before but will say that I never wet sand ebonite and have never noticed heat being a problem with it. I find it more heat tolerant than acrylic. Looking closely at your picture I see radial scratches indicating possibly starting with sandpaper that's too rough and or insufficient sanding through the grits. I always start with 360+ paper sanding lengthwise and then alter radially/lengthwise cleaning between the grits and inspecting it for an even scratch pattern before proceeding. Sand up to 4000 and then buff.
 
I have found that it is the Nikko ebonite, it is not always perfectly black. I would recommend contacting Steve at Vermontfreehand, and getting his advice. He is the expert.
 
Aurelius said:
Were those spots there before ou started sanding or did they appear as you were finishing?
I ask because they look like material defects/inclusions to me.
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They were here before. I went on with finishing because I thought I could match their color and the whole pen would be black then.
 
PatrickR said:
I have not seen those kind of spots before but will say that I never wet sand ebonite and have never noticed heat being a problem with it. I find it more heat tolerant than acrylic. Looking closely at your picture I see radial scratches indicating possibly starting with sandpaper that's too rough and or insufficient sanding through the grits. I always start with 360+ paper sanding lengthwise and then alter radially/lengthwise cleaning between the grits and inspecting it for an even scratch pattern before proceeding. Sand up to 4000 and then buff.
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Interesting statement Patrick. You are the first person to say that Ebonite is more heat tolerant than acrylic. And you are right about the sanding. I spent insufficient time on each grit, I realized that when going thru the process again. What is your buffing setup if I may ask?
 
RobS said:
I have found that it is the Nikko ebonite, it is not always perfectly black. I would recommend contacting Steve at Vermontfreehand, and getting his advice. He is the expert.
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Thank you Rob! I do have some pen parts from the same ebonite rod that doesn't have those spots. I just initially blamed myself for the spots
 
bg15 said:
Interesting statement Patrick. You are the first person to say that Ebonite is more heat tolerant than acrylic. And you are right about the sanding. I spent insufficient time on each grit, I realized that when going thru the process again. What is your buffing setup if I may ask?
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the heat tolerance could vary With manufacturer. i have used some Nikko but the main difference I noticed was that it has a less sulphuric smell. Those spots could be a defect, it is substantially cheaper than the German brands.
after sanding I use Novus 1 & 2 then Mcguires plast-x. If it needs I have a two wheel buffer that I use the finest compounds on (Blue bar and rouge) i don't remember the grits.
Edit: according to Wikipedia ebonite heat tolerance is directly related to the sulfur content.
 
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I started with ebonite grey/red too and I get some very small cracks and little holes in it. I used some ca glue to fill them and after sanding again I got the some spots like you. I noticed that the spots were and the red colour only. Meaby it's a different consistency?
I don't know where the cracks come from. I have the feeling it's the heat of turning.
I don't get the same long ribbons flying off like I get with diamond cast blanks. I use a skew.
 
Not all ebonite is created equal.
I use SEM from Germany, as well as some black Japanese ebonite. I have not heard anything good about ebonite coming out of India, but have never used any.
I use the 3M paper. Wet sand through 5 grits down to 2micron. I also cross sand each grit. When I get to the end, I get a loupe and look for scratches. If I find any, I move back up 2-3 grits and start over. When I only see uniform scratches from the 2 micron, (no deep scratches) I move to the buffer. I have a 4 wheel set up ending with Caswell's Fine Plastic polish.
Definitely wear a mask. I never used to have a problem with ebonite. But this last batch, I forgot to wear a mask for the first 5 minutes, and paid the price. It smells like sulfer going in and burns like sulfer coming out. I paid the price for at least a week.

All that said. Every maker I know of, says that black ebonite is the hardest to polish. Making it the best to practice your technique on. LOL
 
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