Polycarbonate blemishes

[skippydiesel]

Hi All,

 

On removing the upper protective cover (the lower had been removed for installation 12 months ago), of my brand new Polycarbonate canopy, I have found strange blemishes, that do not come off with the application of VuPlex cleaner - anyone have a suggestion?

 

My thanks in anticipation

[Thruster88]

Depending on the depth of blemishes this might work

 https://www.aircraftspruce.com/catalog/cspages/scratchoff.php

[rgmwa]

Silvo works. Be careful as overdoing it will result in visual distortion and may make the problem worse.

[onetrack]

Skippy - Try a loose leaf calico rotary polishing buff attached to a drill or a tapered spindle on a bench grinder, with a small amount of polishing compound.

 

Josco make polishing compound in bars of different colours, blue is the one for plastics.

 

Be careful not to overheat the polycarbonate by constant heavy pressure on, or with, the buff. Gentle, short, repeated buffing efforts prevent heat buildup. Apply small amounts of compound to the spinning buff as needed.

 

https://www.josco.com.au/types/calico-buffs/?pid=9

 

https://www.josco.com.au/types/compounds/?pid=9

 

https://www.josco.com.au/resource/josco-polishing-demonstration/

 

 

 

 

[IBob]

Hi Skippy. When I painted SVA then removed the protective cover on the doors, I found the polycarbonate had a fogged appearance. Presumably the paint solvents had penetrated the protective cover, and in my ignorance I had done nothing to prevent that (I believe the answer is foil masking?).

 

I was relieved to find that the fogging was at the surface, and I was able to remove it with Meguiar's Clay kit, which is an auto product for removing road film and the like.

[skippydiesel]

Thanks Gentlefolk.

 

RGMWA  - "Silvo works. Be careful as overdoing it will result in visual distortion and may make the problem worse." I would be concerned that Silvo contains hydrocarbons, certainly smells like it. To the best of my knowledge hydrocarbons & Polycarbonate don't mix.

 

IBob - ".........fogging .........." My blemishes appear to be on the inner surface, quite random in distribution & shape and mainly on one side. They present as a stain, rather than fog/hazing. There is no raised surface and a finger nail scrape  makes no impression.

 

 IBob - "..........Meguiar's Clay kit........", I have some will give it a try.

 

Thruster -  Thanks but, at $83 US, I might try the cheaper suggestions first.

 

Onetrack -  Josco stuff looks good. Unfortunately the clearance between glair shield and underside of  Sonex "windscreen" (Sonex) to tight for most power equipment. Thanks anyhow.

[rgmwa]

Yes, I was thinking of perspex, so polycarbonate could be a problem. It certainly doesn't like hydrocarbons. 

[IBob]

Good luck, Skippy.
As I recall, the Meguiar's on my fogging required a fair bit of elbow grease. But it sounds as though your discolouration is something different.
 

[440032]

Perhaps consider one of the headlight polish creams like Meguiar's PLASTX polish. I use this on headlights, it works great for me. I'd use it on my canopy glass if I needed to.

[Blueadventures]

talk to some local gliding clubs.  they repair cracks in canopys and polish the repairs to like new.  There also is a 3 compound system for polishing out scratches etc available from sellers of the material.

[facthunter]

A lot of crash helmets are polycarbonate. You might find some information there.  I would never paint one. So I'd keep thinners away.  Nev

[Old Koreelah]

Silvo/Brasso sound a bit harsh for soft plastic; has anyone tried toothpaste?

[bushcaddy105]

Novus 3-stage kit works well on both acrylic (perspex) and polycarbonate screens and canopies. Also does wonders for aging car headlights. Just add elbowgrease.

[skippydiesel]

Good discussion (we all have "plastic" canopies mostly of the Perspex variety).

 

Sonex use Polycarbonate on their forward "windscreen) and Perspex on the hinged main canopy. Polycarbonate is very strong but reacts badly to exposure to hydrocarbons (petrol, paint thinners, etc).

 

Most of you are assuming my problem is hazing and or scratches and making suggestions to minimise or correct the same . Hazing usually associated with exposure to UV  causing a dulling of the surface - my polycarbonate has not flown nor been exposed in any way to UV. Scratches/abrasion caused by all sorts of unfortunate occurrences from a bit of grit on a cleaning cloth to contact with a metal object is also not the problem.

 

My blemishes appear to be on the inner surface, quite random in distribution & shape and mainly on one side. They present as a stain, rather than fog/hazing. There is no raised surface and a finger nail scrape  makes no impression.

[onetrack]

Skippy, photos might assist in a better analysis of what the problem is, and how best to solve it.

[skippydiesel]

4 hours ago, onetrack said:

Skippy, photos might assist in a better analysis of what the problem is, and how best to solve it.

Ever tried getting a photo of something on the inside of a shiny  tinted "window" (my polycarbonate is tinted) - I suspect this would be very much the same.

[facthunter]

Could it be pigment fade. Red particularly is affected.    Nev

[spacesailor]

An Idiot's  question !.

But

How to tell if the clear sheet of plastic iß ' acrilic ' or ' policarbonate ' .

I ,m cutting up some at the moment & it just hit me ! , what is this.

It scores & saws well, but the heat knife is the quickest. 

spacesailor

[onetrack]

Spacey, both acrylic sheet and polycarbonate sheet appear translucent (clear) when looked at at right angles - but when looked at from the edge (looking along the surface), the acrylic appears clear, while the polycarbonate appears blue.

 

[Blueadventures]

18 minutes ago, skippydiesel said:

Ever tried getting a photo of something on the inside of a shiny  tinted "window" (my polycarbonate is tinted) - I suspect this would be very much the same.

Look at it with 35x magnification as may be mid thickness stress or a manufacture flaw and will just have to live with it.  also maybe talk to ollie at Taree as Gary Morgan was moulding canopies and he may know about blemishes.  Or email Sonex for any info they know.

[turboplanner]

22 hours ago, facthunter said:

A lot of crash helmets are polycarbonate. You might find some information there.  I would never paint one. So I'd keep thinners away.  Nev

In racing if they have cracks, or are painted they're usually broken up........in front of the driver. I've seen about half a dozen depart this life.

 

A lot of good ideas here, but I would recommend contacting the manufacturere of the material used. If it's polycarbonate, a polycarbonate manufacturer, not an aircraft manufacturer who just buys it in. There may be grades of polycarbonate or types of polycarbonate. The original manufacture will have the most knowledge of the product and most likley a very simply tried and true solution.

Edited November 10, 2022 by turboplanner

[Old Koreelah]

1 hour ago, spacesailor said:

An Idiot's  question !.

But

How to tell if the clear sheet of plastic iß ' acrilic ' or ' policarbonate ...

Spacey just grab a corner with a vice grip and bend it. Polycarb will bend, acrylic will break.

[kgwilson]

Perspex and plexiglass are just a brands of acrylic and it is easy to restore and remove scratches. There are plenty of branded products but they charge a lot for a few squares of wet & dry, some cutting paste or cream and then some acrylic polish. My bubble canopy somehow got scratched & it was basically quite simple to remove them. When you start with the coarse (about 600 grit) W&D it looks terrible, just an opaque mess. Then as you get finer 1000, 1500, 2000, 3000  it gets smooth and you can start to see everything fairly clearly. After the cutting paste it is almost perfect and then a polish at the end and you would never know there ever was a mark there.

 

Deep scratches can be got rid of the same way but you may end up with a little bit of distortion due to removing a fair amount of the acrylic to get back to a polished surface. Just check out you tube. There are dozens of clips that show you how. The same process is used to completely restore old yellowed headlights and most of these are polycarbonate so the process works for both materials. They come up like new.

[facthunter]

A lot of headlights have a coating that goes off. Cutting compound often fixes them using finer ones at the finish.  Nev

[skippydiesel]

Well the Meguiar's Clay kit has no discernible  benefit - will move to the next level.