Author Topic: Soda blasting shiny plastics  (Read 9484 times)

Offline bry1975

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Soda blasting shiny plastics
« on: June 24, 2011, 03:59:56 AM »
Chaps,

Have any of you soda blasted acrylic(PMMA) plastic? if so will it remove light scratches?


TIA


Bry

Offline PTsideshow

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Re: Soda blasting shiny plastics
« Reply #1 on: June 25, 2011, 06:06:39 AM »
Short answer is no! It is strictly a gentle method for cleaning and remove surface coating of material, graffiti, dirt, paint, mold etc. It works on plastic, metals, fiberglass, stone, brick and some woods As it can get caught in the woods grain structure of some soft woods.

On this side of the pond they are mixing it with an abrasive for light rust removal. It does leave a residue on the material that has to be cleaned off, before painting or other coating process.

They have a kit in the auto parts stores that have a head light covers cleaning and scratch removing kit that may work for you.
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Offline Lew_Merrick_PE

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Re: Soda blasting shiny plastics
« Reply #2 on: June 25, 2011, 11:21:02 AM »
Have any of you soda blasted acrylic(PMMA) plastic? if so will it remove light scratches?

Try a hot air heat gun.  With a little bit of practice it's really quite easy to melt the surface of acrylic materials to gloss over light scratches.  There is a commercial polishing compound for acrylics that works on heavier scratches -- Interstate Plastics (west coast US) sells it under the "Novus" brand name.  I use it every few years to clean up the scratches that accumulate on my Trav-A-Dial units on my milling machine.

Offline bry1975

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Re: Soda blasting shiny plastics
« Reply #3 on: June 25, 2011, 11:46:45 AM »
Thanks chaps.

The glossy plastic I was working with was a right nightmare brand new part but couldn't find a away to clean or remove fluff or grime without scratching so ended up using finest soda beads and then blew the blast media  off with a hand puffer.

Next time I'll try something less likely to peen might try using a plastic blast media.




Offline Jasonb

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Re: Soda blasting shiny plastics
« Reply #4 on: June 25, 2011, 12:19:03 PM »
Try Miocromesh, its designed to take the scratches out of fighter plane canopies, works a treat on plastic, you can buy small starter sets.

http://www.sylmasta.com/acatalog/Online_Catalogue_Micro_Mesh_Abrasives_1.html

Jason

Offline bry1975

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Re: Soda blasting shiny plastics
« Reply #5 on: June 25, 2011, 12:51:59 PM »
Thanks Jason,

I veered from the micromesh route but should try it and polish in one direction.

That's the scratched glossy dial that has been light soda lime blasted with around 15-20psi tops and assembled minus the glass:-



Some of my clients can be quite picky hence have to try and either eliminate,  remove or blend scratches out.  FYI the dial is usually totally transparent and not opaque as the solar panel is directly underneath,  the watch charged perfectly under a UV lamp and should keep a charge for hours if not days.

Offline Topos

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Re: Soda blasting shiny plastics
« Reply #6 on: July 11, 2011, 04:46:56 PM »
A technique I picked up in 1956 at the MIT machine shop was to use toothpaste to
polish plastic. They were making one foot plastic hemi-sphere for a reconnaissance planes.
The final polish was tooth paste and fingers.


 In particular with my 1978 Rolex Sea Dweller I have over the intervening
years polished out scratches with Ultra Brite Tooth paste. Put a dab on the crystal,
wet my thumb, and rubbed in circular patterns. The wet paste works wonders. Patience and multiple applications
for tough scratches. My original crystal is still pristine even though
it has seen many dives.

Offline bry1975

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Re: Soda blasting shiny plastics
« Reply #7 on: July 11, 2011, 05:19:41 PM »
Thanks Topos,

Yea hydrated silica in toothpaste works quite well the more modern acrylic polishing pastes these days are polywatch or xerapol sadly that wouldn't work to well with a glossy dial as you'd still get scratch marks in a certain light.



Offline Marauder

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Re: Soda blasting shiny plastics
« Reply #8 on: September 06, 2011, 03:12:09 AM »
The front plastic windows of my caravan was getting hard to look through,Some one said you need to rub in and polish off  with some of that car paint color restorer called  T Cutt,Ok went to Halfords purchased a bottle came back home and and gave it a go ..It works..Made them look like new,Since tried it on many other plastic acrylic surfaces it works.

Offline Shadow

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Re: Soda blasting shiny plastics
« Reply #9 on: September 06, 2011, 07:36:58 PM »
I have used regular silverware polish to restore dial indicator crystals or acrylic parts. I also use it to polish aluminum. For flat surfaces I put some on a piece of copy paper backed by a flat surface and rub the item over it.

Offline bry1975

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Re: Soda blasting shiny plastics
« Reply #10 on: September 20, 2011, 11:31:13 AM »
Xerapol a german made acrylic polish is recommended it actually dissolves a thin layer which really helps to blend/remove scratches.

Bry