Liquid Wrench

On Wed, 23 Feb 2005 23:34:27 -0500, Sheldon Brown
wrote:

Andy Ksjls wrote:

I got a stuck seat post in a seat tube. Someone suggested Liquid
Wrench. I found it was just some lubricant. Will the more readily
available WD-40 do the job?

Jobst Brandt replied:

That probably won't help either because, although you didn't say so, I
suspect you have a steel frame and an aluminum seat post. When these
two corrode together aluminum expands enough to stretch the seat post.
Yours may not yet be at that point but it probably cannot be removed
non-destructively.

Maybe so, maybe no. See: http://sheldonbrown.com/stuck-seatposts

The way frame builders remove these is to saw them off, bore them out
to a thin shell and grind away a slot in one side to collapse the
aluminum remains to remove them. Oil bases lubricants will not help.
An acid solvent might work its way in there but I doubt it.

Ammonia is good for this...I believe it's a base, not an acid.

Sheldon "Unnnggggggggh!" Brown
+-------------------------------------------------------------+
| If brute force doesn't work, you're not using enough! |
| --BOB Simon |
+-------------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com


I'm not sure that is is really the place for a Dr. King quote. Very
funny though.

LioNiNoiL_a t_Y a h 0 0_d 0 t_c 0 m wrote:
Sheldon Brown wrote:

An acid solvent might work its way in there but I doubt it.


Ammonia is good for this...I believe it's a base, not an acid.


Aqueous ammonia is indeed alkaline [a base], and it is corrosive to
aluminum; but a less toxic corrosive is vinegar [dilute acetic acid].

The base also dissolves the aluminum oxide, aka the corrosion that froze
the seatpost in the frame.

Pat

On Thu, 24 Feb 2005 17:34:19 +0800, Oscar
may have said:

Werehatrack wrote:

WD40 is not as good as a penetrant as Liquid Wrench. Neither is likely
to have much effect in my experience, but LW has the better shot at
actually doing something.

For real hints, start he

http://www.sheldonbrown.com/stuck-seatposts.html


Diesel fuel is better than either of those for penetrating fine gaps.

Its presence on the bike and user may cause both to get evicted from
the house for the duration, though. (But LW doesn't smell much
better, as I recall; it's just a lot less pungent.)

--
My email address is antispammed; pull WEEDS if replying via e-mail.
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Words processed in a facility that contains nuts.

sheldon has the floor!
howbout heating the outside tube
jamming dry ice down the inside
then soaking with PC blaster
repeat

Pat Lamb wrote:

An acid solvent might work its way in there but I doubt it.

Ammonia is good for this...I believe it's a base, not an acid.

Aqueous ammonia is indeed alkaline [a base], and it is corrosive to
aluminum; but a less toxic corrosive is vinegar [dilute acetic acid].

The base also dissolves the aluminum oxide, aka the corrosion that
froze the seatpost in the frame.

You're certain the corrosion is aluminum oxide?

--
"Bicycling is a healthy and manly pursuit with much
to recommend it, and, unlike other foolish crazes,
it has not died out." -- The Daily Telegraph (1877)

If ammonia is corrosive to aluminum, does that mean that using it when
you've got an al post stuck in an al frame might be bad?

On 24.02.05 05:34 Sheldon Brown wrote:
Andy Ksjls wrote:


I got a stuck seat post in a seat tube. Someone suggested Liquid
Wrench. I found it was just some lubricant. Will the more readily
available WD-40 do the job?


Jobst Brandt replied:


That probably won't help either because, although you didn't say so, I
suspect you have a steel frame and an aluminum seat post. When these
two corrode together aluminum expands enough to stretch the seat post.
Yours may not yet be at that point but it probably cannot be removed
non-destructively.


Maybe so, maybe no. See: http://sheldonbrown.com/stuck-seatposts

The way frame builders remove these is to saw them off, bore them out
to a thin shell and grind away a slot in one side to collapse the
aluminum remains to remove them. Oil bases lubricants will not help.
An acid solvent might work its way in there but I doubt it.


Ammonia is good for this...I believe it's a base, not an acid.

Yup, ammonia is a base. For the more extreme cases, a solution of
caustic (AKA sodium hydroxide) literally removes the seatpost. The base
dissolves aluminum forming sodium aluminum hydroxide and hydrogen gas.
Takes some time with thick-walled seatposts, but it works. I tried it
once after using up two hacksaw blades and still not having gone through
the post.

Don't try this at home, kids, and read the MSDS.
--
Størker "sometimes chemistry is useful" Moe
'97 GT Avalanche, '98 Trek 800, '01 Trek Fuel 90

Email Storker(DOT)Moe(AT)c2i(DOT)net
WWW http://home.c2i.net/storker_moe/

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

Bikenate wrote:

If ammonia is corrosive to aluminum, does that mean that
using it when you've got an al post stuck in an al frame
might be bad?

Not in moderation, in order to etch away only the portion that is
preventing the removal of the stuck post. A hasty flushing afterwards
with lots of water will stop the etching. I myself wouldn't use ammonia,
though, because I'm allergic to it.

--
"Bicycling is a healthy and manly pursuit with much
to recommend it, and, unlike other foolish crazes,
it has not died out." -- The Daily Telegraph (1877)

Størker Moe wrote:

Yup, ammonia is a base. For the more extreme cases, a solution of
caustic (AKA sodium hydroxide) literally removes the seatpost. The base
dissolves aluminum forming sodium aluminum hydroxide and hydrogen gas.
Takes some time with thick-walled seatposts, but it works. I tried it
once after using up two hacksaw blades and still not having gone through
the post.

Don't try this at home, kids, and read the MSDS.

Is sodium hydroxide any worse than potassium hydroxide? I have had skin
contact with potassium hydroxide many times and as long as it was washed
off right away, it was not big deal.

Sodium hydroxide is inexpensive - I can buy a bottle of drain cleaner
crystals [1] for a couple of dollars at the grocery store.

[1] It says "100% sodium hydroxide", but I doubt it is reagent purity.

--
Tom Sherman - Earth

Tom Sherman writes:

Størker Moe wrote:

Yup, ammonia is a base. For the more extreme cases, a solution of
caustic (AKA sodium hydroxide) literally removes the seatpost. The
base dissolves aluminum forming sodium aluminum hydroxide and
hydrogen gas. Takes some time with thick-walled seatposts, but it
works. I tried it once after using up two hacksaw blades and still
not having gone through the post.
Don't try this at home, kids, and read the MSDS.

Is sodium hydroxide any worse than potassium hydroxide? I have had
skin contact with potassium hydroxide many times and as long as it was
washed off right away, it was not big deal.

They are both about the same, but don't let your experience with KOH
fool you, these are not exactly benign compounds. They are not
"poisonous" per se, but strong solutions will happily disolve your
flesh. Brief skin contact is no big deal, but get some in your eye or
swallow some and you are likely to have problems. (There are lots of
folks running around who can't eat anymore and have to collect their
spit in a cup because they tried to kill themselves drinking drain
cleaner.) Just use common sense and follow standard safety
precautions like wearing goggles and always adding the crystals to the
water and not the other way around.