Polishing stainless steel

[rick]

I need to polish stainless steel .... these are large (15" propellers)

They are new ... but the stainless has not had a huge effort into polishing during manufacture (annoying at £1400 a set) a lot of it is semi-matt.

I keep them clean on previous boats with Autosol metal polishing paste, it's going to need a bit more than that to get them initially right.

Happy to work my way through wet& dry grades 240, 400, 800, 1200, 2400 ...... but what then ... is Autosol the best for Stainless steel ? The standard Gold packaged Autosol states Chrome, Aluminium & metals. There is a 'Black' packaged that states Chrome, aluminuim, stainless, brass & copper.

Not sure if there is a difference.

[newshound]

At that scale I would say Autosol is an unnecessarily branded luxury. I'd be looking for an industrial polishing compound, perhaps good old "rouge", ISTR that alumina is another option. Also diamond, of course (and indeed you need so little that it might be cost effective).

In the old days when car bumpers were chromed steel I think one of the advantages of autosol was that it also left an organic film on the surface that helped to seal the natural cracks in the chromium. That property won't give any extra benefit with stainless, especially if it is in seawater.

[nightjar]

Start with Carbrax on a close stitched polishing mop for fast removal.

Follow with Steelbrite on an open stitched polish mop for the final finish.

If you want a really good mirror finish, end up with whiting powder on an unstitched mop.

I used to make mirrors for directing lasers in keyhole surgery that way.

[DJC]

Steel, Stainless Steel & Iron.

If the metal is in a poor condition then abrasives will be needed. Thats where experience of polishing comes in, looking at then metal and knowing what process you need to start at. You will need to get the surface to 240/400 grit before you start polishing at process 1. If the condition of metal is not too bad or you have the surface to 600 grit + then you could start at process 2.

Process 1 (Burnishing) Grey 523LBZ compound with a sisal polishing mop

Process 2 (Prepolishing) Green 439T compound with a white close stitched polishing mop

Process 3 (Polishing) Blue P164 Compound or Rose P126 Compound with a Loose G quality

Process 4 (Finishing) P175 for super finishing with a Loose WDR quality mop

also

[Brian Gaff (Sofa]

How much? Really? I'd expect balanced diamond encrusted props for that cost. Brian

[rick]

Thanks .. I'll follow the links

[rick]

Duoprops - contra-rotaing matched pair, where front is larger diam that the rear are very expensive ... This is what I'm talking about ....

and that is a bargain set

[rick]

These are aimed at 4", 6" bench machines ...... to you know if you can get equivalent to suit a die grinder. Due to the curves of the blades etc., a 2" - 3 " pad is going to be much better

[nightjar]

Good luck, but practice on something unimportant first. Carbrax can remove a lot of metal very fast.

[Fredxx]

Does the precise surface make much difference? Sometimes a comparatively rough surface causes less drag.

Some articles suggest a shiny surface suffers from less corrosion.

[rick]

Want them to look good

[The Natural Philosopher]

Yes. The theory is that by creating a small controlled turbulent boundary layer, you avoid a large unstable one.

Reduces the surface area for sure

[Fredxx]

Ok, a good reason.

But once in the water who's going to see this piece of artwork. I'm used to boats that stay in the water that use bronze props

Is this trailered in and out on a regular basis?