Filling a deep scratch in black plastic?

[Mattematical]

Hi folks - this seems like a hard one: does anyone have suggested methods for filling a deep scratch in black plastic? This is too deep to polish off without really messing with the barrel shape of this otherwise perfect Sheaffer Touchdown.

[I-am-not-really-here]

China wax?  Cheap and easy.

[Mattematical]

4 hours ago, I-am-not-really-here said:

China wax?  Cheap and easy.

That's a little less permanent than I would like... I was envisioning making a slurry with methylene chloride and spare plastic to fill it, but that's as far as I've gotten in my mind

[austollie]

Hi Mattematical,

 

That scratch doesn't look that deep to me.  If it were my pen, I'd sand it out with fine abrasive paper and I'd then put it on the polishing wheel.  I've done it before with deeper markings than that (for a 1960s pen where plastic letters had been hot pressed into the ABS barrel in lieu of engraving) and you can't tell afterwards that the pen has been sanded and polished.

[tmenyc]

I also would sand it out -- mask off all but the area you need to sand, use 6000-8000-12000 sanding pads, sand wet and alternate directions to remove the marks of the sanding. After that, a sunshine rag to the whole barrel to even out the polish. Don't push hard with any of it, let the grit do the work. I'd save the solvents; they create their own scars that are often worse than the wounds. 

 

Tim

[GlenV]

I would very much prefer to fill a scratch than sand out as may reflect a flat spot there since shiny black... If you can clean the crack so no bubbles or dirt, clear locktite superglue and then can work down and smooth I use little files. You could fill with just acetone and a bit of donor plastic works if it is a early enough plastic, doesn't work as good for later sheaffer solid color plastic though. Hardener spray doesn't work well with Sheaffer injection molded solid color plastics...caution

[Ron Z]

Trying to fill and then blend the repair may produce the very flaws you're trying to avoid, and introduces other risks into the process. 

[Mattematical]

45 minutes ago, GlenV said:

I would very much prefer to fill a scratch than sand out as may reflect a flat spot there since shiny black... If you can clean the crack so no bubbles or dirt, clear locktite superglue and then can work down and smooth I use little files. You could fill with just acetone and a bit of donor plastic works if it is a early enough plastic, doesn't work as good for later sheaffer solid color plastic though. Hardener spray doesn't work well with Sheaffer injection molded solid color plastics...caution

Thanks for the insight Glen! This is an early large-barrel touchdown; does that qualify as "later sheaffer solid plastic" to you?

[Mattematical]

1 minute ago, Ron Z said:

Trying to fill and then blend the repair may produce the very flaws you're trying to avoid, and introduces other risks into the process. 

Yeah... I am still in information gathering mode right now. I appreciate the insight. I should find a donor barrel to practice on, perhaps...

[GlenV]

Fat touchdowns are nice pens to use. I think still a tip of a straight pin touched on a dab of ca glue to not be risky in any way and would work really well, my errors are if I forget to remove the dab of glue on the desk after and get it on my hand, or worse set something down on it.. I believe the fat touchdowns, like the regular, are not celluloid but are injection molded plastic, and don't fill well like celluloid.

[lcoldfield]

Don't even consider using black filler.  Clear filler is what you need and the correct colour is then picked up from beneath.

I have used clear epoxy for this, but have now found that superglue is better as it sets really hard and crystal clear.  Use the thin version and aooly with a cocktail stick.  Expect to apply more than once if the scratch is really deep.  Use emery sticks for initial polishing back to the coreect profile and then sequence through abrasive grades to 6000 and polish.  I have filled many engravings by this technique, and provided the defect is thoroughly cleared out of any contaminant, you will not be able to find where it was.

[Hanamizu]

23 hours ago, lcoldfield said:

I have used clear epoxy for this, but have now found that superglue is better as it sets really hard and crystal clear.  Use the thin version and aooly with a cocktail stick. 

I used this technique on a pearl grey Parker Vacumatic whose previous owner had personalized it with one of those vibrating engravers. I was quite pleased with the results. You really can't see that the engravings that covered nearly half the barrel were ever there. The striped pattern may have helped. 

 

As stated above, sand it down using ever finer micro mesh pads and if it's deep more than one thin application is better than one thick one. Good luck!