This K75S I recently acquired has a major problem with cracked paint on the side of the front fender. I've hopefully found a matching paint to the orange red color. Thought it was called Marakesh red. But the issue now is how to remove the cracked paint. Some of it just peels/breaks off and I have tried to a knife edge to pop it off in some places. But I was wondering/asking again if anyone has an approach to removing the paint from the plastic bits other than just sanding it down? In a previous thread someone mentioned using brake fluid to soften/loosen paint. But how would that affect the plastic?

Thanks J.

Simply sand it.

Wet sanding is the most successful way I have found. One front guard on my K100 had 9 different colour coats on it.
Before painting make sure you get the correct plastic primer coat or the coats closest to the plastic cracks and will show up as small flaws in the paint and gets worse after a few years. It is a primer used for plastic bumpers on cars.

Rick G wrote:Wet sanding is the most successful way I have found. One front guard on my K100 had 9 different colour coats on it.
Before painting make sure you get the correct plastic primer coat or the coats closest to the plastic cracks and will show up as small flaws in the paint and gets worse after a few years. It is a primer used for plastic bumpers on cars.

I expect to use "UPOL GRIP #4" as an adhesive on the plastic. But my concern is where the paint has splintered and come off in flakes. Sanding and then should I use primer or the adhesive. And how to get a smooth surface when the old paint came off in patches after some collision. Sanding will help but usually I like all of the old paint to come off or be sanded off.

Right back to black plastic then the plastic primer and a light rub with 600 grit and another coat then a light dry rub then the paint primer starts.
I've never had success any other way but remove all the previous paint. I did once use a stripper for plastic but it was just as much work as sandpaper.

Try using oven cleaner.  Wear gloves and test it on the underside of the mudguard.  Rinse with lots of water. 

Get a can of adhesion promoter at the autopaint shop.  This stuff is designed to make primer stick to the flexible bumper fascias on cars.  It is a clear spray that acts as a fast drying adhesive between coats of paint and the plastic.  It's cheap insurance, and I use it almost everywhere now.

Point-Seven-five wrote:Try using oven cleaner.  Wear gloves and test it on the underside of the mudguard.  Rinse with lots of water. 

Thanks Point-Seven-Five, but the oven cleaner didn't seem to affect the paint. But it got me to thinking about water at pressure. And I have one of those cheesy Harbor Freight pressure washers  which I've used at various times. So I tried it. Takes the paint off fairly effectively. Does leave behind the occasional nip of paint but wet sanding will take care of that. Though it is a water waster and apparently mine is failing somewhere internally.The plastic surface it leaves behind is right dark almost black and shiny. If it weren't for the occasional scratch during the cleaning process I'd be tempted to simply leave it.
But thanks for getting me to thinking about how to.

J.

Media blast?

duck wrote:Media blast?

Not sure. Like walnut shells? That sort of thing? I'd want to try it on a disposable part before going with the expensive bits. Well the act of locating another fender might be more costly than a simple purchase.

Maybe soda blasting, however a place that does blasting should be able to recommend a suitable media.
Regards Martin.

Well it worked up till the pressure washer broke. A small plastic nut holding a pressure gauge (I think that's what it is) broke. So I'm into repair of plastics now. Waiting for it to bond, set, and so on.

But I might be in the market for a pressure washer,
J.