Help Sanding Cellulose Acetate

[ruadh80]

I recently picked up some cellulose acetate from a member here. I had never worked with it before. I definitely have a love/hate relationship with this stuff. It is beautiful! It turns like butter, but it is a pain to thread and sanding it is AWEFUL! It instantly corns up your sandpaper. I mean, it corns it up as fast as sanding uncured varnish. I tried it wet, I tried it dry, in a box with a fox... I do not like sanding it here or there, I do not like sanding it anywhere. At one point I stopped sanding and went back over everything with my skew chisel so I could reduce the amount of sanding needed prior to polishing. It does polish up nicely, it takes a little more effort than acrylic or Alumilite, but it will take a glass-like polish.

Are there any tricks to this? Is there a way to reduce the sandpaper corning when sanding this stuff? Or do you just buy a lot of extra sandpaper for it?

 

[hooked]

My guess is that it is getting too hot. It gets gummy as it gets warm. It will melt if you look at it wrong.

If you keep the temperature down while wet sanding it should alleviate your problems. Wet sand at low speed, if any speed at all. If you feel the material warm up, stop and let it cool down.

I find that it really shines when you buff and tend to rely more on buffing than sanding. Once again, you have to avoid it getting hot while buffing or it will melt.

 

[walshjp17]

I tried it wet, I tried it dry, in a box with a fox... I do not like sanding it here or there, I do not like sanding it anywhere

This brilliant Seussification gave me a huge chuckle this morning. Thank you. Have you tried using Mirka's Abranet? It's open weave helps prevent clogging.

 

[ruadh80]

My guess is that it is getting too hot. It gets gummy as it gets warm. It will melt if you look at it wrong.

If you keep the temperature down while wet sanding it should alleviate your problems. Wet sand at low speed, if any speed at all. If you feel the material warm up, stop and let it cool down.

I find that it really shines when you buff and tend to rely more on buffing than sanding. Once again, you have to avoid it getting hot while buffing or it will melt.

I never felt it get warm. I could barely touch the sandpaper to it for a fraction of a second and it would leave corns behind. It corned up when I was hand sanding lengthwise too. I agree it was much easier to just get a nice smooth finish with the skew and then hit it with the buffing wheels.

 

[ruadh80]

I also noticed that it sticks to itself more than other materials. So the cap threads don't turn as smoothly as other materials. Even if you don't screw it down real tight, it takes some force to break that initial grip to unscrew it. The threads also don't polish up as nicely, no matter what, they look kind of dull. I think in the future, I might make the threaded portion of the barrel out of ebonite if I can find a good reliable way to bond the ebonite to the cellulose acetate. The CA cap threads onto an acrylic barrel better than a CA barrel, but it is smoothest on an ebonite barrel.

I've been taking the cap on/off of the pen I made out of CA nonstop like a fidget for a couple days now and while it is a little smoother, it still is pretty sticky. I've tried lubricating it with wax and the effects of it quickly wear off. I have not tried putting a hard wax on a wheel and burnishing it into the threads, but I'm a bit nervous to do that since this stuff melts so easily.

 

[bugradx2]

maybe sand at a slower speed?

 

[d_bondi]

Hi Russ.

I have only made one pen using vintage cellulose acetate (red crush). What grit were you starting with? I typically start with 600 (sometimes I use 400 if there are deeper marks). I use 600, 800 wet and then a Mirka MirlonTotal 1500 flexible sanding pad (like synthetic steel wool). I sand with the lathe at about 1000 rpm and then along the length of the piece with the lathe off. After that it is all buffing wheels with varying compounds.

All the caution about heat is real. Be especially careful if you use buffing wheels not to let it over heat.

As for the threads, My pen only ever had ebonite to cellulose acetate threading because I had to use ebonite for the cap and I had to line the section tube with ebonite so the section tenon was ebonite.

Was the cellulose acetate exposed to any chemicals? How about water for an extended period, like soaked for more than 5-10 minutes?

Lovely pen by the way!! I can't wait to see more photos with the section!

David

 

[ruadh80]

Hi Russ.

I have only made one pen using vintage cellulose acetate (red crush). What grit were you starting with? I typically start with 600 (sometimes I use 400 if there are deeper marks). I use 600, 800 wet and then a Mirka MirlonTotal 1500 flexible sanding pad (like synthetic steel wool). I sand with the lathe at about 1000 rpm and then along the length of the piece with the lathe off. After that it is all buffing wheels with varying compounds.

All the caution about heat is real. Be especially careful if you use buffing wheels not to let it over heat.

As for the threads, My pen only ever had ebonite to cellulose acetate threading because I had to use ebonite for the cap and I had to line the section tube with ebonite so the section tenon was ebonite.

Was the cellulose acetate exposed to any chemicals? How about water for an extended period, like soaked for more than 5-10 minutes?

Lovely pen by the way!! I can't wait to see more photos with the section!

David

I was starting with 400 grit and then moving on to 800, but even with the 800 it was pretty gummy. I just got the material, so I don't know if it had been exposed to any chemicals or water. It hasn't since it has been in my possession. It buffed up quite nicely with the wheels, no problem there. Next time I might try sanding pads instead of paper, maybe that will work better.

Cellulose acetate to ebonite threading is silky smooth, its just CA to CA that is a real letdown (and CA to acrylic to a lesser extent).