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Old 13th Sep 2023, 7:48 pm   #1
samjmann
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Default Acrylic/Perspex cover polishing.

I know this must have been asked previously. What's the current favourite method for polishing the cover of a turntable? I've used T-Cut and this removed the light scratches. But is there anything that will cut deeper? Xerapol polish seems popular now, has any one used it?

Thanks for any advice offered. SJM.
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Old 13th Sep 2023, 8:39 pm   #2
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Default Re: Acrylic/Perspex cover polishing.

There are polishing kits for plastic headlight lenses. comes with a woollen polishing head, to go into a small variable speed electric drill chuck, and a tube of abrasive polish. I used one recently and was impressed. The head is still useable with alternative sources of abrasive. Farecla ones come in different grades from motor factors. Keep revs down to avoid heat softening.

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Old 13th Sep 2023, 8:44 pm   #3
FIXITNOW
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Default Re: Acrylic/Perspex cover polishing.

something like this
https://www.polishingjewellery.co.uk...shing-plastic/

course grade working to the finest grade
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Old 13th Sep 2023, 9:38 pm   #4
ajgriff
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Default Re: Acrylic/Perspex cover polishing.

Please see this post:

https://www.vintage-radio.net/forum/...0&postcount=25

As an example the attached photo shows part of a turntable cover which had an opaque area about the size of a saucer presumably caused by solvent damage. The cover was polished by hand with cerium oxide.

Alan
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Old 14th Sep 2023, 2:01 pm   #5
David G4EBT
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Default Re: Acrylic/Perspex cover polishing.

Much depends on how much effort and expense you want to put into it. The least time and expense is much to be preferred of course! You might get satisfactory results using a fine polish. After all, it's a lid to keep dust off and you aren't going to be standing over it looking at it at close quarters as you would be at a wristwatch lens for example, several times a day.

That said, the human eye is remarkably discerning when it comes to spotting scratches on acrylic. If you use micromesh polishing pads, (with which you use water as a lubricant), the pads start at 1,500 grit and typically have eight or nine grades finishing with 12,000 grit.

You can buy sets of 3" Velcro backed discs which fit onto a hook and loop pad, held on an arbor for used at slow speed in a cordless drill.

My main experience of polishing in in woodturning, in particular, pens which are turned from acrylic blanks. That's done on the lathe using square micromesh pads. In the early stages I wasted a lot of time thinking I could speed up the process by skipping a few grades. I soon found that was a waste of time.

If you think of the scratches as microscopic 'hills' and 'valleys' on the surface of the acrylic, you need to take the tops off the hills, which leaves scratches consisting of smaller hills, then the next grade take the top off those, leaving hills that are smaller still, until there are no scratches visible to the human eye, which is generally assumed to be 12,000g.

Sets of Micro Mesh Discs for fine polishing on plastic, acrylic and metals tend to range from 1,500g to 12,000.

EG: From this link, choose:

Regular set of nine 3” Velcro backed discs, grades 1,500 thru 12,000 for use on Plastic, Acrylic, wood, gold and silver:

https://moleroda.com/product/micro-mesh-discs/

Drill arbor with Velcro backed pad:

https://www.autocraze.co.uk/3-arbor-...1-pc.html.html

Foam interface pad which fits between the rigid pad on the arbor and the polishing disc:

https://www.autocraze.co.uk/3-foam-i...1-pc.html.html

Micromesh pads are quite long lasting.

I've had a set of pads for pen polishing for two years similar to the ones at this link below, with which I've polished many pens and the pads are still perfectly good. They're used wet, and from the reviews you'll see that they're also used for jewellery, and even for polishing fountain pen nibs:

https://www.amazon.co.uk/Micro-Mesh-...15&sr=8-5&th=1

Hope that might be of interest.
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Old 14th Sep 2023, 8:47 pm   #6
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Default Re: Acrylic/Perspex cover polishing.

If you have a scratch which may require a silly amount of material to be removed, there is the option to fill the scratch.
Good results come from using UV glass glue. Applied very carefully in very small amounts , then cured with a UV light or leave out in sun.
You are then left with just any raised glue to polish down rather than removing large amounts of material down to the level of the scratch.
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Old 14th Sep 2023, 9:23 pm   #7
samjmann
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Default Re: Acrylic/Perspex cover polishing.

Thank you all for such detailed and informative answers. The headlight kits do look good and if they use the 3" pad it can be used afterwards.

I've got a broken scratched cover to 'practice on'. As was said, I haven't got the confidence to polish out what say 1000g would leave in getting out a deep scratch.

I was surprised what a difference T-cut made using just a microfiber cloth! So a bit of practice with a rotary and not getting carried away with the drill on to fast a speed.

Once again thanks for going into such detail and providing the links. Regards, SJM
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Old 18th Sep 2023, 2:31 pm   #8
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Default Re: Acrylic/Perspex cover polishing.

Wasn't there a thread about not using brasso or hydrocarbon solvent polishes on acrylic lest it go foggy? I can't find it now, but remember drilling something like that into my brain so I didn't do it...
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Old 18th Sep 2023, 9:57 pm   #9
David G4EBT
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Default Re: Acrylic/Perspex cover polishing.

Quote:
Originally Posted by Uncle Bulgaria View Post
Wasn't there a thread about not using brasso or hydrocarbon solvent polishes on acrylic lest it go foggy? I can't find it now, but remember drilling something like that into my brain so I didn't do it...
This might be of interest:

https://en.m.wikipedia.org/wiki/Brasso

(Note the comments on cleaning acrylic crystal watch faces and computer screens).
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