Liquid Wrench - Page 4 - Cycling Mob: Road Cycling, Mountain Biking and More

02-24-2005, 05:11 PM

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?

02-24-2005, 11:02 PM

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: [Only registered and activated users can see links. ]
>
>> 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 [Only registered and activated users can see links. ]

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?

02-24-2005, 11:02 PM

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: [Only registered and activated users can see links. ]
>
>> 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 [Only registered and activated users can see links. ]

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?

02-25-2005, 02:20 PM

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)

02-25-2005, 02:20 PM

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)

02-25-2005, 05:35 PM

In article <1109293868.414441.194070@o13g2000cwo.googlegroups .com>,
"[Only registered and activated users can see links. ]" <[Only registered and activated users can see links. ]> writes:

> 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?

In that sort of case, I consider there might not be much
(bimetallic/galvanic) corrosion to remove with ammonia
anyway, because the seatpost and frame metal might not
be too dissimilar. I'm not sure about that, though.

cheers,
Tom

--
-- Nothing is safe from me.
Above address is just a spam midden.
I'm really at: tkeats [curlicue] vcn [point] bc [point] ca

02-25-2005, 05:35 PM

In article <1109293868.414441.194070@o13g2000cwo.googlegroups .com>,
"[Only registered and activated users can see links. ]" <[Only registered and activated users can see links. ]> writes:

> 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?

In that sort of case, I consider there might not be much
(bimetallic/galvanic) corrosion to remove with ammonia
anyway, because the seatpost and frame metal might not
be too dissimilar. I'm not sure about that, though.

cheers,
Tom

--
-- Nothing is safe from me.
Above address is just a spam midden.
I'm really at: tkeats [curlicue] vcn [point] bc [point] ca

02-25-2005, 06:20 PM

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

02-25-2005, 06:20 PM

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

02-25-2005, 09:39 PM

Tom Sherman <[Only registered and activated users can see links. ]> 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.