Scratches on plastic - how to polish? - Page 1
Forum section: electronics / beginners

author: aluck
author_rank: Regular Contributor
timestamp: February 05, 2012, 05:47:36 am
content: I have some old touch-screen devices that have minor scratches on screens - just the usual wear.Does someone have a positive experience on how to polish them? Maybe you know a nice chemical to do that?

author: DBaron
author_rank: Newbie
timestamp: February 05, 2012, 06:06:05 am
content: Novus products work great on most plastics. Number 2 is the best for light scratches, followed by number 1 for final shine. Order it online or check local motorcycle shops. They have it for polishing windshields. Tap Plastics also has it if you've got one of those nearby.Of course, try it on a small area or on something you don't care about first to make sure it's compatible with your particular plastic.

author: Rerouter
author_rank: Super Contributor
timestamp: February 05, 2012, 06:41:52 am
content: if they are only shallow scratchs, brasso can be used,

author: updatelee
author_rank: Contributor
timestamp: February 05, 2012, 07:53:45 am
content: Quote from: aluck on February 05, 2012, 05:47:36 amIve used scratch-X on harder plastics with excellent results. Never used it on softer plastics like touch screens though.

author: grenert
author_rank: Frequent Contributor
timestamp: February 05, 2012, 08:33:17 am
content: Check out the product linked to in this older forum posting:https://www.eevblog.com/forum/projects-designs-and-technical-stuff/renew-the-look-of-your-digital-meters-lcd/msg4516/#msg4516I've had VERY good luck with it: DMM displays, MP3 player screen, eyeglass frames (NOT LENSES!) .

author: sonicj
author_rank: Frequent Contributor
timestamp: February 05, 2012, 09:44:57 am
content: Novus #2

author: SeanB
author_rank: Super Contributor
timestamp: February 05, 2012, 11:03:12 am
content: Try a plastics supply shop and ask for Perpex polish. Works well on most clear plastics to remove scratches in the surface. Most common use is for newer car headlights.

author: flolic
author_rank: Frequent Contributor
timestamp: February 05, 2012, 11:52:07 am
content: Xerapol is another excellent polish for plastic

author: aluck
author_rank: Regular Contributor
timestamp: February 05, 2012, 04:22:10 pm
content: Ordered Xerapol from ebay. Going to try it and post before/after.

author: Unknown
author_rank: Unknown
timestamp: February 05, 2012, 05:34:37 pm
content: I heard of toothpaste being used to polish plexiglass. Presumably the grainy particles (calcite?) are soft enough to polish without scratching. Never tried it though...

author: sonicj
author_rank: Frequent Contributor
timestamp: February 05, 2012, 06:11:07 pm
content: a polishing wheel is the fastest / easiest by far. the palm pilot was almost unreadable when i got it. no before photo though...-sj

author: aluck
author_rank: Regular Contributor
timestamp: February 28, 2012, 01:50:11 pm
content: Xerapol arrived. Made no magic - really deep scratches are still there...

author: entereev
author_rank: Contributor
timestamp: February 28, 2012, 02:42:06 pm
content: Toothpaste, Baking soda are good enough for fine scratches. Deeper ones require 1000+ grit sandpaper.

author: Time
author_rank: Frequent Contributor
timestamp: February 28, 2012, 05:32:10 pm
content: A lot of times you can't polish out really deep scratches. You need to get some kind of epoxy filler first.

author: Fraser
author_rank: Super Contributor
timestamp: February 28, 2012, 06:14:51 pm
content: The way to remove deep scratches from plastic is a little frightening but it works very well.As a scratch is a depression in the level of the plastic the ONLY way to actually remove it is to lower the surrounding plastic to the depth of the scratch. Filling is an option using skill and a polishing wheel to melt the surrounding plastic and level the scratch but unless you are highly experienced, most people will ruin the plastic in the process.Ok, how do you level the plastic to the depth of the scratch ? easy....wet & dry abrasive paperIt sounds an awful idea but is actually very straight forward. You use 1500 grit wet and dry paper, combined with lots of water, to sand the plastic until the scratches are no longer visible,. It is important to sand in one direction only and not circular motions. Once the scratches are removed, you will be left with an opaque surface...looks a bit frightening but all is still OKThe surface, looked at under a microscope, is covered in tiny low penetration scratches.Such low penetration scratches are easily removed with a quality plastic polish such as that made by NOVUS. You apply NOVUS No.3 (course) first using a soft cotton cloth and use a linear polishing motion, with decent pressure, ACROSS the direction of the scratches. Once the transparency of the plastic starts to return, you can apply less pressure and use a circular polishing motion .The plastic will return to a reasonably clear state with some minor fine scratches. It is very important to use a nice soft cotton cloth so as to avoid causing scratches to the surface. Wash the surface clean and NEVER try to polish the plastic with a cloth containing dried polish. Never attempt to polish a surface on which the polish has dried, use more liquid polish to lift it off, or bad scratches will occur.Next apply NOVUS No.2 (Medium) polish and proceed to polish the plastic carefully in circular and linear motions until the plastic shines and is virtually scratch free. There should only be the slightest evidence of scratches on the surface when viewed at a shallow angle in strong light. When that polishing stage is complete the plastic may be used 'as-is' in many cases. Wash theplastic carefully in clean water and pat dry with a soft towel. A microfibre cloth may then be used to polish the plastic to a good lustre.To really finish it off you can use NOVUS No.1 (Fine+seal) polish. No.1 is very thin fluid, like water, and will remove only the finest of scratches. It also acts as a surface cleaner and sealer for the plastic. Again, after use, wash the plastic and pat dry with a soft towel, then polish to a lustre with a microfibre cloth like that used for spectacles (glasses).This method works on most hard plastics but NOT polycarbonate or coated plastics. It is for you to decide how suitable your plastics are for polishing. Always have a good practice on some scrap plastic before using polishing techniques on valued equipment. I practiced on clear CD cases and an old mobile phone screen.Watch restorers use the above procedure in order to restore plastic watch faces to 'as-new' condition. You could google 'watch glass restoration' to find out more.Have fun .... its scary the first time you do it, but easy from there onRegardsAurora

author: sonicj
author_rank: Frequent Contributor
timestamp: February 28, 2012, 07:13:25 pm
content: good info Aurora!i usually take a more aggressive approach, but i've been polishing stuff for years so stepping down in grit is no biggie. so yea, if Aurora's method is too slow or not removing deeper scratches, step down in grit a notch and try again. if 1500 is too slow, step down to 1k. if 1k isn't fast enough, step down to 800. starting high like 1500 is a safe bet. i also like to start with slightly used sandpaper as the chunkier bits of grit have already been worn off. my 2¢ fwiw.-sj

author: aluck
author_rank: Regular Contributor
timestamp: February 28, 2012, 07:30:02 pm
content: How to tell polycarbonate from some other plastic? Is it ever used for making touchscreens?