CA Finish Issue

[Kevin Campbell]

I have been turning for a few months, but only have a little free time. I've done about 15 pens, and about 25 rings. I do not love CA glue as a finish, but I have done ok with it. 2 out of the last 3 pens I have had the same problem. When sanding the finish, through the grits of micro mesh, I start getting black lines through the finish. I don't know if it's the glue, or the micro mesh. I've thought maybe my glue is old, although it's not very old at all. I wonder if the glue got hot during sanding, or if maybe the mm is breaking down. I got away from using activator, because I had a very nice pen that the finish shattered on. It looks like a broken windshield, all over the entire surface. I try to let each coat dry, then add another. After all coats are on, I let it turn to dry completely, before sanding. The latest pen never seemed to get beyond tacky. Any advice here would be appreciated. Thanks,

Kevin

 

[AlanZ]

By some chance are you picking up some black from bushings at the ends of the blanks?
This only really applies when using a mandrel.
If so, try working between centers, without bushings (a good thing for finishing anyway)

 

[Dean Center]

I had a similar problem a couple years ago and if memory serves, it was a result of heat build up from applying too much pressure while sanding. I suppose it could also result from the CA not being absolutely cured, which would then not cut cleaning with the sandpaper and produce heat.

 

[Kevin Campbell]

Alan, I guess it is possible it could be from the bushings, although they seem pretty pristine.

Dean, that could be it, too. I have used the mm a bit, and never had that problem until the last couple weeks.

 

[Steve Worcester]

I would suspect the micro mesh. It is not really heat tolerant. Better to use standard abrasives up to 1000, then polishes.
I am not a fan of Micro Mesh

 

[Bill Boehme]

It sounds like the substrate of the Micromesh is being melted. Micromesh has a rubber base and you should only use it with the lathe not running or running very slow. For the finer grits turn the lathe off and polish by hand. If possible use the Micromesh wet and rinse frequently. Also, don't apply more than very light pressure and keep the Micromesh moving so that you're not keeping the same area in contact with the pen.

Get the surface level and smooth using regular sandpaper before using the Micromesh and use the Micromesh only to polish the finish. Make sure that you sand along the length of the pen so that there is a nice smooth curve without ripples. Use high quality sandpaper. Cheap sandpaper may leave deep scratches that can't be polished out by the Micromesh. I like Norton ProSand ceramic paper, but there are many others.

 

[Kevin Campbell]

Thanks for the replies. I do believe it is the rubber substrate. It has happened in the range of 3200 to 3600 grit.