Polishing Delrin

What is the best way to get a shiny finish on black Delrin?

I've got a piece of Delrin that I want to get a shiny finish on, the sort of finish that comes as supplied new. I've used successively finer grades of abrasive down to 2000 and then used Solvo Autosol by hand to try and get a shine. No success, it just remains a dull black.

I don't want to use a buff in case I melt the stuff (which I have done before).

Dave
The Emerald Isle

Hi Dave. I have used & machined quite a lot of Delrin / Acetal. It is funny stuff, almost greasy. I think you were on the right step with wet & dry. But i think something like car wax or similar maybe the way to go. Carnuba wax , which i use on fibre glass molds may work. My thinking is not cream or liquid car polish but the actual wax sort.

Like you say to much friction would mark it..

My local car accessory shop sells up to 3000 grit paper. Which i use when polishing rings etc. I guess the finer the better.

If you do not have any of the above let me know & i will have a go tomorrow on some & post the results.

Another thought is bumper, back to black for cars. It has silicon in it. ????

Steve.

Edited By Steviegtr on 15/12/2020 21:19:19

Thanks, Steve.

I'll try furniture polish first, then if that doesn't work, I've got some car trim restorer that works well on black plastic.

I'll report back when I've had a go.

Dave
The Emerald Isle

I've found I could get an attractive shiny finish machining with a sharp tool and a very fine feed, even if only taking a few tenths depth of cut.

Edited By Mick B1 on 15/12/2020 21:38:07

Hi Dave I have made small parts in black acetal. To get a nice uniform finish I have flame polished the parts, just waft a propane flame over the part until it looks glossy, but not too long or it will bubble and ruin it. I ended up with a lovely satin gloss finish which felt really smooth to the touch.

Another technique is to use use a nail polishing buffing block, like the manicurists use. they have the sequence 1,2,3,4 with 4 being the polishing side

IanJ

I get good results with spare bits of carpet....I have some off cuts from laying carpet and use them on the acetates but three methods, namely, rub the plastic part on the carpet piece,...or, apply directly to parts i nthe lathe,..or, just work the carpet piece against the part while it's in vice or hand.

......Only thing is, don't use used carpet pieces because they are contaminated with grit and other foreign bodies that score the plastic.

I usually use Micro-Mesh for finishing plastics which goes down to 6000g then a liquid cutting compound.

Can you paint it?

Back to Black is a silicone oil another use is when sprayed on a small piece of cloth and then rubbed on car door seals prevents the doors freezing shut.

The part that is not a regular shaped item so it had to be filed to rough shape and then down to the wet 'n' dry.

Following on from steviegtr's suggestion, I used some black trim restorer. That didn't seem to make much difference, so then on to furniture polish and that seemed to produce a satisfactory result.

Thanks to all the other ideas.

Dave
The Emerald Isle

Edited By steamdave on 22/12/2020 12:33:47

Great tip!!

My car used to have a useful seal strip along the bottom of both doors but it froze and got snapped out when I opened the door.

I can now get a new one and prevent a reoccurrence.

And get black stuff on my trousers.

Roger,

Silicone oil works down to single figure of frost (say about -7C / 20F), but below that you need to use Vaseline on the door rubbers. How do I know? Cold weather testing in Canada down to -45C! Door key locks, in the days before 'plippers', we had to unfreeze with a Zippo lighter.