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topic 18957

Aluminum threads galled and frozen

A discussion started in 2003 and continuing through 2020
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Q. I'm hoping one of the experts here can offer some advice. I have a pair of aluminum rings that thread together to hold a filter on the front of a camera. Lack of care by the previous owner caused them to freeze together. These rings are about 4" in diameter, .2" high, and turned to about a .075 - .090 thickness, so any heavy force is likely to bend them out of round. They appear to be a hard, stiff alloy like 5000 or 6000 series with hard black anodizing. As a professional camera part, the threads are very fine, the fit is very close, and the surface finish makes a Rolex look cheap. There is knurling on the outside of each ring intended to provide a grip to separate them. Turning by hand will not break them loose. Usually, the manufacturer uses a bayonet fitting instead of threads, or makes one part out of brass, but not this time. Any thoughts on how I might separate them?

My first attempt was to spray some WD-40 into the joint and let it soak. No effect. I also tried heating the outer ring with a hair dryer, but that didn't help either, as it wasn't possible to get much of a temperature differential between the two rings.

My next thought would be something like Liquid Wrench [affil. link to info/product on Amazon] - but I thought I'd get some advice first. There is paint in engraved lettering on the rings I'd like to keep, so really strong solvents would be a last resort.

Any thoughts?

Robert Bleidt
- Santa Clara, California, USA


A. Hi, Robert. When it comes to aluminum-to-aluminum galling I've pretty much given up trying to light candles, and resigned myself to cursing the darkness. After a lifetime of broken bulbs because the bases are aluminum, hacksawing of frozen aluminum hose couplings, aluminum keys stuck in locks, and a dozen similar petty aggravations: If it has a thread or a moving part and it's aluminum, I don't want it.

The manufacturers may disagree with me but I've never seen any big difference between WD-40 [affil. link to info/product on Amazon] and Liquid Wrench, so I don't think the Liquid Wrench is going to be your salvation.

I hope you prove me wrong, but my prediction is that filter ring is coming off only with a hacksaw.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


A. Just a thought. No guarantees ! Try to determine which of the parts has the female threads. Once that has been determined, put the parts in your freezer for a couple of hours until they get as cold as they can get. Warm a hot plate or similar item (stove burner if electric)and after removing the parts from the freezer, immediately place the female part of the connection on the warm element for a few seconds then quickly try to unthread them. This may take several attempts to get the temperature differential just right. Good luck.

Bill Miller
- Shinnston, West Virginia


Q. I was away on a trip for several days, and had left the WD-40 on the part. Today I picked it up and it unscrewed like it had never been frozen, without any effort at all. Last week, I would have bet that the wall of the part would snap before the threads came loose. Apparently, 4-5 days of soaking had an effect.

Any suggestions on how I might keep this from happening again? I was thinking of some sort of lubricant or anti-seize product. WD-40 seems to have done the job, but it tends to migrate away from the area it was applied, and could get on the lens. Cleaning a $3000 lens is a serious matter, and you're limited to sodium lauryl sulfate, methanol, or Acetone [affil. link to info/product on Amazon] as solvents.

Robert Bleidt
- Santa Clara, California, USA


A. Find a local anodizer and ask them to do the following:
1) Measure the anodic thickness to determine whether hard or conventional ( Mil-A-8625 [link is to free spec spec at Defense Logistics Agency, dla.mil] Type II) anodize.
2) Soak clean (ultrasonic if available) to remove WD-40.
3) Mask the lettering area with a tape resistant to step 4).
4) Remove any corrosion in the threads (and the unprotected anodize) using hot chromic acid-phosphoric acid solution per ASTM B137 [affil. link to spec at Techstreet]. It may take longer than usual due to limited diffusion, but this solution should not harm the aluminum.
5) Re-anodize* the separated parts, dye and seal.
6) Remove masking and touch-up if necessary.

*Owing to the thinness of the parts and uncertain alloy, perhaps do Type II anodizing regardless of initial anodize.

Ken Vlach
- Goleta, California

contributor of the year

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thumbs up sign Surprised and happy to hear that it came apart after 4 days of WD-40!

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


A. Robert,

Interesting reading re. galling!

To prevent this happening again, here are two ideas.

l. Use teflon tape ... then they'll never freeze together.
2. Get some molyslip ... but because it is very viscous, dilute with an appropriate solvent such as methonol, but not acetone. And if you're short of methanol, use Vodka or Canadian Club !

I used to keep a hypodermic (a glass one!) filled with this ... highly useful for getting into awkward places in order to lubricate them pdq.

freeman newton portrait
Freeman Newton [dec.]
White Rock, British Columbia, Canada

(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)

Will Loctite prevent galling/seizing in tapped aluminum threads?


Q. I am installing 304 fasteners in a cast aluminum, high vibration situation. I need to know how to prevent galling and also prevent the bolts from backing out without the use of lock washers. Will LOCTITE prevent galling?

Sonny Smoyer
paints - Frederick, Maryland

affil. link
"Tightening Threaded Fasteners - A Designer's Notebook"
from Abe Books



A. There are many kinds of Loctite as well as numerous similar products from the competition. Prevent galling, probably not. Reduce galling, yes. The degree will depend on many factors that you have not given.

James Watts
- Navarre, Florida

thumbs up signHi Sonny. My personal experience, not based on scientific study, is that threads in aluminum are almost always bad news: light bulbs stuck in sockets, hoses that won't unscrew from faucets, aluminum keys that won't come out of locks ... I think James is exactly right that the Loctite may be useful but is no guarantee. If you want it right, see if you can figure out a nut and bolt arrangement with nyloc nuts instead of the tapped aluminum. Good luck.


Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha

June 10, 2019

A. Hi, you can use Loctite or you can buy fasteners with Butanone pre-applied to them. You can reuse them up to 5 times. There is some more information about them here: www.accu.co.uk/en/p/45-thread-locking-patches.


Harry Crowther
Engineering - Sheffield, Yorkshire

April 10, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. A few years ago I acquired a fairly large (6 inches dia.) astronomical telescope that was made of aluminum. It had a pretty heavy brass screw-on lens cap. After playing with it for a while, I put the cap on and sat it in the garage. A few years later, now I decided to get it out but the brass cap is stuck on--hard! I don't want to pound, heat, or otherwise abuse it and hurt the expensive lens. Is there any way to dissolve the aluminum oxide, or whatever it is, so I can get the cap off? Is there any other method? Thanks

Bill Hankins
Hobbyist - Tuscaloosa, Alabama USA

April 11, 2011

A. Hi, Bill. Maybe you'll get lucky like Robert did. Put the WD-40 or Liquid Wrench on and wait several days. Good luck.


Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha

Brass spray nozzle stuck on an aluminum hose end

June 23, 2020 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. My brass nozzles get so tight on a hose end that is aluminum, I can't unscrew them. Why? And what can I do about them?
Thanks for your reply.

Gordon Mortensen
- Queen Creek, Arizona USA

June 24, 2020

A. The first thing I'd do is take note of the brand name of your hose and make a pledge to yourself to never buy anything from that company again :-)

Because every engineer knows full well the curse they are laying upon the user when they specify aluminum instead of brass hose ends; it wasn't an error, it was a choice -- and that it was done solely in the name of cheap is bad enough ... but if they colored them yellow to deliberately deceive you, there ought to be a law, but there isn't.

At this point, try WD-40 and patience. Apply it, tap-tap-tap, do the same several days in a row, then some channel locks or vice grips. Next time you can try a thread lubricant and hope for the best, but as a guy who has had to carefully hacksaw aluminum hose ends off of hose bibs, and who wasn't able to ever find a King Arthur able to pull the aluminum key out of my garage door lock, I won't promise it :-)

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

November 6, 2020

! All garden hoses now are imported from the China and fitted with brass threads on the connection side to the house but brass threads are covered with an aluminum threaded connection to the house faucet. All new hoses are like this and Ace Hardware is no exception. These hoses have an aluminum connection pressed onto the brass fitting that is pressed into the hose. Wow. I am having a problem getting the hose off the faucet on the outside of the house. I finally got it off by cutting the aluminum.

Robert Majcher
- Mesa, Arizona

November 2020

thumbs up sign Thanks Robert. I wouldn't know if it's all hoses but it certainly seems to be most.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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