Have I messed this up? Windsurfer refurbishment

[MauiBreeze]

I have picked up an old Hifly Motion board, in generally good condition, its got a few stains and scratches. The construction material is polypropylene and on the underside the finish is a 'satin', not matt or gloss.

I should preface this post by saying I am one of those people who like to detail cars and watch lots of videos showing dirty cars being detailed and I'm bit anal about scratches and marks. Its cold out and we are locked down, so what else am I going to do today?

Method so far

1. Wash x 2 with washing up liquid, stiff brush and sponge.
2. Removed some of the rust with rust remover, most remained.
3. Removed black marks with Tardis. Use this on cars to get rid of tar spots.
4. Tried various products on the rust, most effective was Jif and Brillo Pad.

I decided to do something about the scratches and and into trouble. On a small underside area I used 120 grit wet an dry followed by 320 then compound on a DA polisher. This did not completely remove the scratches but improved the colour and removed the staining. I then applied some some car high quality polish but now I cannot get a shine to the surface, it is matt, not even the satin finish I am trying to achieve.

Can anyone suggest a solution? Is it possible to get a shine on polypropylene which has been sanded? John

 

[RJJ]

I would go and peruse the Topper association website...my guess is you need to go higher on the grit

 

[duncan99210]

You need to use a series of increasingly fine wet and dry papers until you’ve almost got a shiny appearance: think 1200 or higher. Then you move on to compounding the surface to get the final finish you want. Take your time and it should work.

 

[wully1]

Just go sail it off a sandy beach....

polyethylene is a nightmare to try and repair. The surface will be difficult if not impossible to get any kind of finish on.

Good Luck!

 

[TernVI]

Normally, this time of year I'm fixing gelcoat scratches to my Laser. Alas last year it didn't see much action....

I would suggest much finer w&d paper, I normally use 1200 and then 2000 or higher number, before picking up a polishing machine.
But some plastics are not very co=operative, especially as they get older and more UV'ed.

 

[AntarcticPilot]

WARNING! I have no experience whatsoever, so this is a thought experiment!

But Polyethylene is usually welded using heat, and it melts at quite low temperatures; that could be part of the trouble with using abrasives. Would ironing it (through a suitable damp cloth to keep the temperature under control) work? Obviously, something to be tried with caution, as you only want to melt the surface layer.

 

[TLouth7]

Would ironing it (through a suitable damp cloth to keep the temperature under control) work? Obviously, something to be tried with caution, as you only want to melt the surface layer.

I'd suggest using a heat gun (or hairdryer) rather than an iron. We use this technique to improve the surface finish of 3D printed parts all the time, though I haven't tried it on polyethylene. There is a risk of course of ending up with an unfair surface.

 

[wully1]

From bitter experience trying to repair polyethylene windsurfers applying heat to weld

Nothing, nothing ,nothing. A bit more heat. Nothing,nothing ,nothing. Big hole......rod stuck

 

[Spyro]

polyethylene is so soft. Sanding or compounding won’t work. Scrub it best you can and go sailing.

 

[MauiBreeze]

Thanks all for your responses.

The construction material is polypropylene rather than polyethylene so its a bit harder and seems to sand okay. I am not going to take heat to it, seems too risky based on the comments here. The plan now is to remove the polish I applied then, wet sand with 600 then 1200 grit paper. Then take the DA polisher to it.

The top has a textured non slip surface from the mold which I want to keep and I don't want to damage the decals. Going to try a good cleaning with Jif or similar and then Starbrite Deck Cleaner. Might try Starbrite Hull Cleaner but wasn't that impressed with Starbrite Rust Remover on the polypropylene, which is strange as I know Starbrite Rust Remover works well on gelcoat.

 

[AntarcticPilot]

Thanks all for your responses.

The construction material is polypropylene rather than polyethylene so its a bit harder and seems to sand okay. I am not going to take heat to it, seems too risky based on the comments here. The plan now is to remove the polish I applied then, wet sand with 600 then 1200 grit paper. Then take the DA polisher to it.

The top has a textured non slip surface from the mold which I want to keep and I don't want to damage the decals. Going to try a good cleaning with Jif or similar and then Starbrite Deck Cleaner. Might try Starbrite Hull Cleaner but wasn't that impressed with Starbrite Rust Remover on the polypropylene, which is strange as I know Starbrite Rust Remover works well on gelcoat.

Have you tried plain Oxalic acid on the rust stains?

 

[MauiBreeze]

Have you tried plain Oxalic acid on the rust stains?

I didn't try this AntarticPilot. Starbrite Rust Remover has 8% Oxalic acid. For now going to continue with Jif and Brillo Pad. If that doesn't work will try Oxalic acid.

 

[AntarcticPilot]

I didn't try this AntarticPilot. Starbrite Rust Remover has 8% Oxalic acid. For now going to continue with Jif and Brillo Pad. If that doesn't work will try Oxalic acid.

You need quite a strong solution, and leave it on for hours rather than minutes. In this cold weather it will be slow to act, too.

 

[Ink]

You need quite a strong solution, and leave it on for hours rather than minutes. In this cold weather it will be slow to act, too.

What you are applying oxalic acid to needs to be above 8deg for it to work.

Ink

 

[Bodach na mara]

You seem to be using methods designed for refinishing polyester gel coat when you're board is made of polypropylene, similar to the stuff that plastic buckets and basins are made from. Several of the other posters are making the same mistake. I have no experience of trying to refinish soft plastics like polypropylene or polyethylene, only trying to fix holes in fenders and mooring buoys and failing miserably. Although the polymer that the board is made from will be harder than the stuff used for domestic plastic basins etc. I doubt that you will be able to achieve much in the way of returning the surface to its original state. Sorry about that but some things are just made to be disposable

 

[northwind]

 

[ronsurf]

The plastic is far too soft to get a polish on. The finish is meant to be satin/matt. I'd go up to about 600 grit and leave it that

Oxalic acid mixed with wallpaper paste for the rust, or just sand it out.