Ebonite spots

[bg15]

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?

 

[PatrickR]

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.

 

[Aurelius]

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.

 

[RobS]

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.

 

[showcaser]

Just had the same problem with a cap I made. I'd like to know more about it also.

 

[bg15]

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.

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.

 

[bg15]

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.

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?

 

[bg15]

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.

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

 

[PatrickR]

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?

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.

 

[Niels]

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.

 

[darrin1200]

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