WD-40 and crack propagation

It sounds like complete bollocks to me.
I can understand it causing propagation of craks in some PLASTICS but not a metal.
I've seen problems with Loctite used to lock a thread on a brass insert in a plastic component causing the plastic to degrade (mic boom in an aviation headset ...whoops)

(Usual disclaimers apply)

Del

I'm with Del on this one.

WD-40 is about 80% descented mineral spirits. How does that contribute to cracking?

It has an anticorrosion package in it but no chlorine/chlorides so ????

I'll bet it would play hell on various foams

milo

I seem to remember reading it is primarily denatured fish oil with some anti-polymerisation additives (which may be corrosive to some metals). The same article said it was produced for NASA as a Water Dispersant hence the name, 24 was the twenty fourth time they reformulated it after testing...

Of course if it were used improperly as a Lube oil instead of water dispersant it would probably accelerate wear by drying out the parts

Guest N:

Might you be thinking of Kroil or AeroKroil? I believe these contain some form of fish oil, but I'm pretty sure WD-40 does not.

- Guest N+1

Good comment, it acts as a solvent. Many mechanics I know mistake it for a pure lubricant.

with you on the using it on dissimilar material as in plastic and brass, transfer all the stress to the weaker material.

But when they the so called experts which is nothing more than bureaucrats, when in doubt cover you butt. too bad there are not more qualified people with some 'practical' material science background making these decisions.

Hello Laughing Jaguar

Refer to the statement by WD-40 makers: http://motocross.transworld.net/2006/11/21/tuesday-tip-the-wd-40-debate/

Preserving Aircraft Outdoors has several references to extensive use of WD-40 on vintage and other long-stored aircraft quite successfully.

Perhaps if the WD-40 liquid is not fully wiped off, but penetrates into micro-cracks then freezes at altitude, the crack may propagate further.

Water, having a high surface tension, would not penetrate such micro-cracks, thus not extend the cracks further.

WD-40 application does seem to prevent correct bonding of paint to aluminium.

Kind Regards....

Sparky may have something here...

Years ago, as a kid, I made money doing valve/head jobs (no smart remarks) in my dad's garage. If you've ever done this, you know that you clean the carbon off the cylinder heads with a hand drill holding a fluted-out wire brush. Anyway, one day my dad came home with a new toy - A huge, two-handed, all steel "Dremel tool." This thing was a beast! It ran at 30,000 RPMs; and if you turned it on with a wire brush in the chuck, everything got sprayed with the wires that made up the brush! The trick was to turn it on only when the wire brush was held against something, like the cylinder head. This thing cut the time it took to clean the carbon from a cylinder head by about 90%!!! Worked great!

One day, though, I got a valve job for an engine with an aluminum head. The head was throughly cleaned, and now it was time to remove the carbon using the 30,000 RPM monster Dremel tool. When I turned it on, in just seconds, the cylinder head was completely filled with oil! The oil just seemed to appear from nowhere!!!

Later, I reasoned that the oil was hiding, absorbed within the aluminum metal, and that the 30,000 RPM vibration made it come oozing back out of its hiding place. If this is correct, I could imagine WD-40 penetrating aluminum, and later causing all sorts of problems.

Come and listen to a story about a man named Verm
A poor mechanic workin' for the family firm,
Then one day while messin' under a hood,
Whoa! Outta nowhere came a bubblin crude!

Oil that is, black gold, Texas tea.

Well the first thing you know ol Verm's a millionaire,
Kinfolk said "Verm move away from there"
Said "Californy is the place you ought to be"
So he loaded up his truck and moved to Beverly.

Hills, that is. Swimmin' pools, movie stars.

looking at this in terms of basic physics, I envision the very end of the crack as a micron sized crevice with metal under stress and metal can rebond if the gap is airtight as the stress is relieved, but if there is a film of lubricant then each time a stress opens the crack, the lube covers the exposed metal and when the stress goes away the gap closes, but the metals do not bond. Next stress, the gap quickly opens to the depth of the lube wetted zone and expans the crevice, which is then covered and the crack gradually propagates.

This seems to be something that would have been looked into.

a google search finds almost 10,000 hits.

http://www.google.ca/search?hl=en&q=%22crack+propagation%22+%2Blubricant+%2Bstress&btnG=Google+Search&meta=

WD-40 application does seem to prevent correct bonding of paint to aluminium.

Is that surprising ? I suspect that a teflon spray would also prevent correct bonding of paint to aluminum.

While serving in the RN in the 60s and 70s, we used to wash off the whole of the magnesium airframe of our helicopters to remove any salt deposits picked up after a flight. I never saw any corrosion or cracks that could be attributed to WD40.

We used to get it in 10 gallon cans! I sure would like one of those today.......

Really great stuff. Also, as far as I am aware, there is nothing in it that could freeze and cause a crack to extend......not that I have placed it in a freezer to find out.

All the intercontinental rockets of the 50s and 60s were protected from moisture with WD40......which is why it is sometimes call Rocket WD 40, or Rocket War Department 40th. mixture.....

It is even used to lubricate machines for preparing food stuffs.....

Ya think maybe the expected useable life of the crafts may have been so short non-compliance didn't matter

Actually,

WD40 is not aproved for incidental contact in food processing.

That would require a H-1 classification.

Back to the matter of those undisclosed ingredients......

Several years ago a plant I worked at failed AIB [american institute of baking] audit, when WD40 was discovered in the maintainance shop. Lubrication in a food processing environment, is another sticky wicket. H-1 lubricants suck, since the base is usually mineral oil & aren't very good when high temps are involved. Then there the matter of the copious amounts of water & harsh cleaners...

As others have pointed out Wd40 is not a very good lubricant.

I've seen an aluminium alternator sprayed with WD40, sealed in an airtight, heat-ssealed bag as a spare for a world cruising yacht. When we tried to use it it was corroded as if it had been laying in a wet bilge for a couple of months. If Wd40 does that to the outside i could well imagine it would extend a crack.

Chas

Agree. WD40 has good anti-friction characteristics, but, enclose metal sprayed with it and you'll note that it does not protect the surface in long term storage. That's my main concern about it.

About using it to release bolts during disassembly, and then send parts for cleaning, inspection, and adequate preservation procedures, I see no problem.

Would a lubricated crack have more freedom of motion? Would this additional motion, even if VERY SMALL, cause more stress at the end of the crack and therefore increase the rate of crack propagation?

This would only have a chance of being true if vibration were present to cause the material "broken free" by the crack to move more than it would have moved if the crack was not present.

And yes:

1) If the crack was going to grow with the WD40 present then it would have grown dry (but possibly slower, maybe giving the plane one more landing).

2) If there is any truth to the above idea then you could substitute 10W30 or any other oil for WD30 and still have the same argument.

I have never heard of WD40 causing cracks in metal, however, spraying liquids onto metal surfaces is an old technique for locating cracks. Could it be that people have located cracks by spraying WD40 on them and blamed the liquid for causing the cracks? After all, if you couldn't see the crack prior to spraying the liquid on it and you could see the crack after, some may have confused cause with effect.

welder man yours and the ;ast posts are perhaps the best responses to the issue.if as i suspect that what i had been told years ago is true one of the resaons the wd40 is so good as a penetrtant that it not only covers minute cracks but waterproofs the area around them is because it has a seal oil component to it.

as for the causing the cracks ithat statement is by my experience and more likely yours is more than likely to be bullpuckey. whoever put that memo out did not intend to go beyond a attorney's suggestion? warning? minibrick load? of we have to find something to blame for the prop blades to disintegrate other than bad castings or if it was rebuilt done improper balancing and testing of it before recertifying the prop as fit for use intended.

i don't know if you ever used singer sewing machine oil and baking soda to locate fine cracks in 5 or 10 horse motor end bells so they could be repaired. the idea works great but it is a real bear to clean out the oil from the metal fatigue fracture line's site even though the cracks show up real good in the baking soda. i think the same thin could have happenned in this case but like i just wrote it is more likely some d.n.g.s. and recommed the prop for use then it disintegrated.

'da ber

I wonder where WD-40 would be used on aircraft? I've used it to loosen frozen bolts and as a rust inhibitor. It's downside is, as a solvent it will remove grease where it's needed. Because it penetrates well, it gets into bearings and small recesses where grease could be required. It also lubricates, so bolts can get stretched past their yield when torqued to spec.

Maybe WD-40 was used to free oxidized aluminum? Maybe the metal had corroded excessively? After all, corrosion on aluminum isn't that unsightly, and the application of oil would disguise the oxidation.

May not be an issue with WD40 but at least one other product used to loosen nuts and bolts WILL indeed promote corrosion in aluminum left to stand in contact with steel (I would guess just about any product made specifically for that purpose). Maybe that is how the controversy started in relation to the aviation maintenance facilities.

Another person mentionned to me a long time ago that the residues would attract bug that would later decompose and produce an harmfull juice. That was not a reliable source but, that guy proved to be right in at least one instance.

I cannot think of any reason why WD-40 would cause cracking in Aluminum. I CAN think of one way in which it MIGHT in some steels. But this is only an outside possibility and I don't give it much creedence even then. IF there is any sulfur in the product (and I'm not at all sure that there is!) then if used on a highly stressed steel part that has nickel as an alloying component, you could have an instance of liquid metal embrittlement. If memory serves, WD-40 is chemically not terribly different from Kerosene or Deisel or Varsol. So if the part can withstand contact with any of them, it should be able to handle WD-40. The MSDS gives no indication that there is any sulfur in the product.

Liquid metal embrittlement is a great insight. It occurrs at temperatures where one of the involved metallic constituents is liquid. It seems to involve a change in bulk properties due to changes at the grain boundaries phenomenon. (Think of every grain being surrounded first by slush, then by ice).

WD-40 would have burned off at those temperature for steel or aluminum. This is a great point, in that this is the proposed method that we think makes Bismuth an enhancer of machinability. (Bhattacharya, 1981 US Patents : 4741786, 4666515, 4786466) but it is at temperatures above which the WD-40 would vaporize.

good thinking.

milo

How it was taught to me (or at least how I remember it was ) sulfur and nickel combine to form a low melting point eutectic alloy that leaches the nickel out of the alloy and leaves behind a liquid metal that has a larger volume than the original metallic nickel, forcing a crack to propagate through the now "foamy" alloy matrix. Mercury, Tin, Cadmium, Indium, Selenium, Gadolinium, and Zinc can also do this as well, depending on the alloy system in question. I think Zinc might form one with Aluminum, I'm not sure. But that said the process is pretty much immediate, you'll hear the crack form essentially on contact if the temp is high enough for the resulting alloy to form and melt. That is why sulfur is used in cutting fluids for nickel based alloys. You have to be careful and wash it off thoroughly however or you can have cracking problems later.

Even if the hydrocarbon carrier of the WD-40 burned off, if there was a zinc based anti-corrosion additive that was left behind it MIGHT act similarly.

That said, I don't recall temperature being mentioned as a process component in the problem Laughing Jaguar mentioned. But then again maybe I was sleeping when it came up and didn't notice.

LJ, fatigue cracking is by definition going to accellerate as it progresses. the load doesn't change but the cross-section it is distributed across is steadily getting smaller and smaller, therefore the localized stress is getting higher and higher. This is what causes the 'beach marks" to get farther and farther apart as the crack progresses.

I have not checked the pH of WD-40 lately, but I seem to remember the product being acidic.

a simple test and unscientific field test is rubbing between your fingers, if its rather slimy and slick its above 7 alkaline, if its tacky/sticky its below 7 acidic

if as i related having recalled having been totld that seal oil is the 10% other material that is part of the w d 40 formula then there is no way that there could not be anything but a acid content to the material BUT that acid will be one of several that are under the name essential polyunsaturated fatty acids.

what i am finding fascinating is that with the number of bio chemical engineers and metallurgists who read this web page not one of them has offered anything near a non technobabbled opinion about what is in the product that could possibly be a factor in the air forces' banning of the compound or what could possibly be a reason to associate it with cracking of metal structures.

does that not strike you as really odd?

'da ber

many years back I applied WD40 on the Selector switch of my Micronta analogue multimeter, to counter moisture deposition related problems. moisture problem was solved but within four months the plastic studs/pillars & the Selector switch itself simply broke off rendering an excellent device use less !

that it causes fatigue in Aluminium alloy too is news to me

thanks

pkd.

plastics and hydrocarbon solvents rarely make a good mix.

plastic and UV also

We had a standing rule in the intermediate aircraft repair facility "Do not use WD-40 on hot materials" due the ingredients in the proprietary secret sauce thought to be or include carbon tetrachloride

unless it has been reformulated, there is no Carbon tetrachloride in WD-40. If it were it would show up on the MSDS.

When installing Walk In Coolers, many moon ago. Many installers would wipe down any corrosion with WD-40 to make the Aluminum all shiny again.

I did this when I started but I soon noticed that the corrosion was far worse in a day or two when I came back. When I asked about this the reply was "yes it is worse but it is just to keep the customer from complaining when they do an inspection. Once we are gone who cares".

This was the outside skins of cooler panels. One application would make any corrosion twice as bad once the WD-40 had evaporated. In a crack the evaporation and corrosion would be magnified do to longer evaporation times.

Just an observation

Brad

Good point, maybe we didn't use WD-40 on hot parts because people acted like Winnie the pooh from breathing the fumes

Or because when combined with water the differential in expansion were unpredictable especially when you're Winnie the pooh bear

I don't know, I try not to huff VOCs. Gives me a headache.

I'm no fan of WD-40 the only things I use it for is: wasp and hornet killer; and to add to ether starting fluid so as not to get a dry cylinder when all else fails at starting a piston engine.

Brad

It used to come in a pressurized aluminum can...

http://www.highbeam.com/doc/1G1-110738696.html

milo

Coca-Cola comes in an Aluminum can. if it was on the outside the can would last minutes. Liners do wonders.

Brad

I don't know about metals, or such, but it does stop squeaks. I sprayed it on a cricket, and the little booger just sat there, rubbing his feet together, trying to make noise, and couldn't.The WD got so hot, it began to smoke,a little wisp rising from the cricket's feet. He didn't bust into flame, but I think it may have ruined his love life. - BM Guest

The smoke was his exoskeleton melting. I've never seen an insect last More than a second after petroleum distillates. Took out a Yellow Jacket nest 6 inches across this summer with a can of WD-40 and a can of wasp and hornet foam. The foam knocked them out of the air and they crawled a bit. The WD-40 they were dead by the time they hit the ground or just twitched.

Brad

When I worked with airframe and power plant mechanics they told me that WD-40 was not really a lubricant, but suitable for cleaning. I was told it was "water based". Since it often seems to "Lubricate", I used it lubricating the throttle slide channel for my motorcycle, which wasn't supposed to be lubricated at all. It was Rochester New York winter and I lost the use of my handlebar throttle control and had to operate my Kilmer Carb by hand. This would imply that Blue WD40 is not recommended as a lubricant in the cold. Further it would imply that there is some good reason aviation mechanics would view it as dangerous. There is the rarely available Red can WD40 that is supposed to be a true lubricant. -Reported to displace water. This is the second time WD 40 has come up in my readings and correspondence in the past week and I wonder if the company has initiated thoughts about WD40. P.S. Stopping skin cracks by drilling a round hole at the terminus of them was interesting to me.

I did a little Google searching on WD-40. Lots there. Quickly apparent is that they try real hard to make a secret out of the ingredient list. The MSDS basically lists hydrocarbons and 10% no problem (my words) ingredients. I'd be willing to bet the "deep dark secret" act is what turned off the FAA folks.

As one who has many times placed my faith in the way the FAA manages airline safety in general and aircraft maintenance in particular I am ready to 100% support a position that "secret potions" not be used in the maintenance of airplanes. That may well be the only reason they banned its use.

My primary use of WD-40 is for the cheap and easy rusty fastener removal jobs. For the really tough jobs I use the more expensive product, Kroil. I suspect there are other Kroil-like products; just haven't tried any for long enough to draw conclusions. My experience is that Kroil very often works where WD-40 won't.

I've long heeded the fairly common wisdom that WD-40 is not really suitable for rust protection and may even accelerate rusting. I have other stuff for that. And I hasten to note the commentaries about how WD-40 will loosen rust giving the appearance of creating new rust but not actually causing new rust.

I did pick up some mention about WD-40 containing "fish oil" whatever that means. Whether this has a basis in known truth or is a rumor based on other "fish oil" applications such as Rustoleum Rusty metal primer I don't really know.

BTW, this damp proof primer or Rusty Metal Primer, as they call it now, really works; I've been using it some 40 years now. I put it on the surface rust pits on an antique car (which I still own) 35 years ago and let it sit outside for 5 years. I sanded it smooth, sprayed it with acrylic primer/sealer and acrylic laquer finish coats 30 years ago. It didn't bubble then and it is still good today, 30 years later.

WD-40 does work very nicely as a quick kill for annoying insects and spiders although I avoid spraying it on surfaces that may have to be painted sometime in the future.

Ed Weldon

I'm no fan of WD40 ether. Several years ago, I worked part-time in a high end bicycle shop. We'd get people in all the time with shifting problem's, and our first question was, "what did you use for a chain lube?". 9 chances out of 10, they would say WD40. We would clean it off, and apply a real bike chain lubricant.

I like the idea that the FAA, or whoever, can't live with the idea to use a product with a "secret formula".

reference drilling a hole at the end of a crack to limit growth: This is an old welder/mechanic trick from way back.Sometimes if you weld a crack without the hole, it will reappear further down the original spot.The hole prevents a stress riser from forming as the metal expands and contracts.It tends to spread the stress evenly around the perimeter of the hole,reducing concentrated forces from accumulating. MY.02$ worth

This is an old welder/mechanic trick from way back.

they do that with saw blades from saw mills.

I don't think that would be an approved method with a plane's structure full of holes.

I don't think that would be an approved method with a plane's structure full of holes.

Other than a plane's structure is full of holes

Actually its why aircraft windows are radius corners rather than sharp.

The brits used square cornered windows on the comet.

Till they figured out why they were falling out of the sky.

Also, riveted small pieces of metal do not allow cracks to travel as far as monocoque construction. thus, many small riveted pieces. Cracks would be contained to the single piece.

milo

In critical mission applications such as aircraft, safety is higher priority than in other applications. Remember the square headlights of the 60s-70s. The scientists warned Madison Ave. stylists that square is not reliable from a stress viewpoint. History shows that the stylists won that argument. Don't count on engineering logic to prevail in all cases.

Not really, most modern headlights nowadays use cylindrical bulbs in a non-pressure containing reflector assembly. You can't get around physics. You may have to change the way you look at something, but physics is immutable.

I guess I didn't make myself clear. The stylists won the contest in the 60s and 70s when square headlights were common. This was done over the objections of engineers and scientists who demonstrated the high stress concentration and lower reliability of square shapes. Eventually, higher bulb envelope temperatures forced return to lower stress shapes, but only after the stylists had their way for many years. Physics is immutable, but often misunderstood. Also, program managers think about $$$ first, physics second.

did not know that,

but you can't blame engineering for using its experience thou faulty at times.

Hi, Milo!

Yeah. And at one time the hatches to the holds on ships used square corners

too

oo

_oo

*

_*

!

Mark

"And at one time the hatches to the holds on ships used square corners"

And the early boilers were square, and we know how that worked out.

The square windows were not the reason for the accidents, (the corners were rounded if you look carefully!) the real reason was that all the rivet holes for the mainframe were punched, not drilled. Including those for the window frames as well....

This caused minute cracks around the rivet holes in a stressed skin that was very thin. Some flights later the vibration of flying would allow the cracks to propagate and the aircraft would start to come apart while flying. Once one piece of metal was lost, the speed of the wind while flying ripped the rest of the skin to threads......the fuselage would disintegrate into several pieces within a few seconds.....

Today all rivet holes are carefully and accurately drilled, with special drilss, so that cracks are not produced. Also, the frames are crack checked before assembly.....

There are some inaccurate web sites around that purport to know what caused the problems with the Comets, but are way off in accuracy.....maybe that is what mislead you.....

Many Comets are still flying, some in a different guise, for the RAF, in long range search aircraft called the Orion if my memory serves me well! They can stay in the air for 24 hours at a time and cover vast sea areas at the same time!!! The aircraft is a long way from being dead!!!

Exactly how many still fly I cannot say as I have no idea.......but when one remembers that it was the world's first passenger jet aircraft, it was not really surprising that some serious "Birth Pains" were the result.......

Andy, It is true that many of the military versions of the Comet are still flying, but they have one attribute that the commercial variant did not. No Windows (ok, FEW windows).

I think you may be partially correct about the method of holemaking playing a role, but I have to think it was the relatively minor one of giving a crack a place to start, if it were not there it would have been something else, few metalworking processes leave a completely microcrack free surface. I still believe that the geometry of the hole was the overriding factor based on the fact that not a single airliner porthole since then has been square, they have all been oval. The consesnsus of all the failure analysis that I have seen has been window geometry. If you can point to studies that refute that, please do so.

According to my materials lecturer, some 7 or 8 years after the Comet left commercial service, the main cause of the fatigue failures was an underestimate of the effect of repeated cycles of pressurization and depressurization of the fuselage. I believe this was the first commercial pressurized aircraft.

That was the basic cause, the thinness of the aluminium and the level of pressurization were further points, all made worse by punching rivet holes instead of drilling them....

A pretty accurate article on this Aircraft and its faults can be found here.

Hi, Andy Germany!

Wow!

Thanks for that. Until I read your entry it hadn't crossed my mind that punch vs drill would have been an obvious tear initiator.

Mark

Don't blame yourself, it wasn't obvious to De Haviland till many aircraft fell out of the sky and they had invented a new way to test a completed aircraft (water tank!).......

Dear Ed, I have no verifiable knowledge about blue can or red can WD-40, but do suspect that the Red Can was made to use when the Blue Can was not appropriate, and overall consider WD40 useful, up to a non critical point. In general people use WD40 as a lubricant. I have myself, though it is a lubricant of last resort in non critical applications from advice and experience. 10 percent secret stuff is not acceptable to my ethics in critical applications. I am almost sorry I know as much about WD40 as I do. Do not use WD40 as a lubricant on anything that will get cold. It is okay for door hinges or cleaning. The rare Red Can formula is probably superior, but it is rare, and also has unknown properties. We of CR4 may want to make sure a Chemist eats these thoughts and throws up on us something wise about WD40.

Here is the text of an inquiry I made to the manufacturer today. Perhaps they will respond.

"A discussion group on an engineering forum has questioned the contention by several FAA inspectors that WD-40 may not be used on airframe components due to the claim that the product causes or promotes cracking in aluminum alloys. Several of us with some metallugical background have looked at the MSDS contents and can find no basis for that claim based on the contents listed. However there is a 10% by volume content that is only described as "inert" which we cannot assign a risk factor to. Is there any information that your company can share that will enlighten us (or the FAA inspectors)? The URL is: http://cr4.globalspec.com/thread/29944/WD-40-and-crack-propagation"

I apologized for being a dumb American,

I also apologized for our short term memory as well as a very, very short attention spa………..look a ball a string just rolled across the floor.

I, too, confess to being dumb. And where is my brain? God only knows. But I do enjoy my A.D.D. nonetheless.

Phoenix911, that is my ball of string. Look! A butterfly!

A very good answer. It sure seems that someone is not taking his happy pills.

Maybe he's barfing up naglers.

...Sorry barf, I just couldn't resist it!

naglers? happy pills? neither just have bit of a problem understanding how educated people can be so ignorant of being ignorant of the world around them how it was shaped and how thier think about it shapes up. thanks for the civilzed reply, very respectful.

'da ber

actually if you take the time to g.o.ya. spend about 45 minutes reading and use another 45 to think about what i wrote you might be somehow able to comprehend the import of the message i posted.

'da ber

Why spend an hour and a half pondering tripe from some git who's just slapped my face? Everyone here -- sans possibly yourself -- has better things to do.

I read that crap you posted and once I press 'Send' I won't waste another nanosecond reading nor responding to your worthless posts. You don't deserve my time. You do deserve a swift kick in the ass and I'm wearing boots but, like I said ...

Ciao, sucker. We'll miss your sweet laughter.