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MennoR

WD40 corrosive or not; your opinion / expertise please!

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I need some input/help: Chemistry wasn't my forte at school (sorry Professor Pete) so I need to ask here. 

As many (some) of you know, I'm knee-deep into sailing. Most materials on a boat are non-corrosive or it takes a lot of time before 'oxidation (rust) gets a grip on parts. 

Here's the problem: on a sailing-related forum someone wrote:

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Since then I have been super finicky with my masts, always cleaning them and ensuring that they are corrosion-free, rinsing them with fresh water after every sail and giving the stainless steel/aluminum junctions a coat of WD40 oil to try prevent corrosion for as long as possible. 
 

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Then today, someone commented:

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It's a cleaning product, it has paint thinner in it (solvent) and has very little lubricant. It's good to de-grip rusted screws but it'll generate more rust than before.

It's not meant to protect the surface, actually, it's the other way around.

For galvanic corrosion (two different metals in contact) use tefgel or similar, for metal protection I use an amazing french product called Mecacyl, but I'm pretty sure there are others just as good...

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Well, I never noticed the corrosive result of using WD40. 

Surely, most of us here are 'heavy users' or all sorts of anti-corrosive 

 

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I have noticed many time that a cleaned metal item sprayed in WD40 does tend to start showing rust way quicker than I would have expected, I never use it any more other than as a release agent, and then I find that PlusGas works better.  I now use either a silicon spray or a fine grease spray if I want some temporary corrosion resistance.

I have no idea of the chemistry of WD40 though.

NB Silcon spray is shit if you intend to subsequently paint the part though, as to remove it completely takes more effort than getting the part clean in the first place.

Alan

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What is the hull / deck made from ? I wouldn't use WD40 any  where near wood where it will penetrate varnishes and seams.

Why not use PTFE spray which  is a similarly  priced, has good anti-corrosion properties and will not stain. A squirt down the luff will allow the main to slide nicely along the mast.

 

Alan 

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The thinners part makes sense, but I would think even a small amount of oil content would give some protection. I feel an experiment coming on....

I like chain lube as protection/grease or whatever. A bit sticky, but seems to work well. I also by cheap toolstation aerosol wax protect stuff which is reasonable at its job (but use dinitrol for proper protection)

Apparently Plusgas sent Guy Martin a box of cans to try, with a view to sponsership. Some time later he refused on the basis it was not as good as WD40... (I have some cans of plusgas, agood friend works for Norton Abrasives, a sister company so he gets some samples, but they tightened up on freebies a couple ofyears ago, so I actually have to buy discs now)

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Plus gas or super de grippant for rusty bolts, WD40 do a version, not sure if you can get that in your island.

For bolting thinks together at sea then it's aqua lube you need, sticky messy stuff but been using it for 30 years and it works, they now call it aqua shield but it's the same stuff.

RR

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But it's got shelack in it, which is the 40th try at water proofing, basically a very fine varnish, don't use the stuff on your Purdy 12 bore.

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Hi Menno,

           when you ask people what they use WD40 for many of the answers circle around some form of cleaning. 

Its high solvent content obviously do the cleaning.

If you have two dissimilar metals in contact the last thing you want to do is clean off any oil deposits Put more oil on not WD40.

Ideally any Ali in contact with other metals needs to be Anodised. This gives a non-conductive coating to the Ali.

Indeed wash off the salt water with fresh water. Apply oil/grease,  Keep the WD40 safely in the dustbin.

 

Roger

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1 hour ago, PeterC said:

Menno, I'm no chemist !  The safty data sheet https://cdn.wd40company.eu/wd-40/en-GB/uploads/2018/01/22135517/WD-40-MULTI-USE-PRODUCT-Non-Aerosol.pdf

shows 80% is solvents and the rest unspecified mineral oil and paraffin wax. No silicone oil it seems.

Peter

 

I know, but you're the highest educated in (more or less) this field I know of. 

@ Roger: that underlines the second of the two quotes I posted. Thanks.

 

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Duck oil..... for preservation 

Plus Gas for rusty fasteners 

WD40 for wet wiring, especially HT leads. WD is for Water Dispersant.

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I had a bare metal Vitesse bonnet on the car in a damp lock-up for twelve years. The only thing protecting it was coating's of WD40, I maybe gave it another coating once a year, max. Often the bonnet was covered in droplets of water from the leaky roof. Over time layers biuld up and it does discolour to a light rusty brown colour, but if you scrape the layers of WD off the surface with your nail there is shiny metal beneath.

Finally degreased and resprayed last month. Used a pressure washer with degreser and couple of wipeovers with thinners, came back to shiny metal with little effort and no signs of rust, and no issues when paint spraying.

Used the same process years ago on a bare metal Vitesse tub restored out in the open over a year. After repairing a section I just gave it a couple of coates of WD40 and left it until the next time with no issues.

This is on mild steel, not used it to protect any other metals.

Mark

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As said above, WD stands for Water Dispersant.      I use it routinely after cleaning parts in degreaser.    Spray of WD, blow off the water with the airline, store.     I needed to get out some conrods recently, that were in a previously failed engine.    I had lightened them by grinding and polishing, had them shot peened before use.     The only protection they had was WD, and after some years in store, they had no rust at all.

On chewing gum etc, the advertising blurb for WD40 goes on about the thosuands of uses people have found for it.  I am reminded of the veneration that is shown across the Atlantic for "Marvel Mystery Oil", which will clean your engine, improve perfomance by better ignition, or else by reduced friction,  be best damper oil in your carburettors and stop leaks in your gearbox!   Some incompatible claims there, but never mind.   In America, "Seafoam" has a similar evangelical following.

  WD is, of course, American, but they invented snake oil too.

John

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UPDATE:

Hey presto: an answer within 60mins after posting my email!

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Hi Menno,

 
Thank you very much for this information.   This is very interesting and does indeed give me something to work with.
 
Thanks again and best regards, 
Todd
 

Menno

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Nice that you got a quick and positive reply Menno. I'm hooked on Project Farm videos, so I'll be watching with interest to see if Todd does one on WD40 and rust. 

Darren

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