Brake Pedal still mushy after brake job

Um, "air" is a mixture of several gases, the most prevalent one being
Nitrogen (approx. 78% IIRC). Hard to imagine any significant difference
in diffusing.

http://education.jlab.org/itselemental/ele007.html

Reminds me somewhat of the "enriched" water for sale in my local deli a
few years ago. It was enriched with extra oxygen to promote good health
- I asked the guy how he could differentiate it from hydrogen peroxide
(H2O2). Got a really blank look.

 

Unlike plain old air, race cars sometimes use pure nitrogen in the
tires becasue the pressure build-up as the tire heats up is more
predictable. Pure notrigen also doesn't react with the rubber inside
your tires to an extent.

This "enriched" water has excess oxygen, more than the 2 to 1 ratio
of H2O water. There are two types; one with a high reduction
potential (ionized "enriched" water) and the other with a high oxidation
potential like H2O2.

And, yes, I do take this "enriched" water and H2O2. H2O2,
on the hand, reacts with your tissues just like plain old
oxygen do to tires.

 

Which has what to do with the OP's question regarding *diffusion*?

The only place O2 does a human being any good is in the lungs (and
subsequently the bloodstream - do you know why cardiac patients and
people who've had diving accidents are put on O2 and why it's via a
nasal cannula/face mask and not by mouth or injection?), otherwise it's
free radicals and harmful - how badly do you want to oxidize your GI tract?

 

Can't you differentiate by pumping the brakes? if you cannot pump the
brakes to stiffness (each successive pump remains spongey) then it's
probably the master cylinder seals?

 

well, dissolved oxygen is definitely not peroxide...

 

as you probably remember from biology classes and the semi-permeable
membrane experiment, diffusion depends on molecule size. as stated
earlier, air is a mix of gases, some being larger, some smaller than
nitrogen. if pure nitrogen is used, the diffusion rate will /not/
include the relatively rapid "disappearance" of the small molecules.

 

if it's still spongy, there's still air in the system. seals are
effectively inelastic.

 

Ever tasted peroxide? Yuck.

This "enriched" water in the deli is the same stuff you create in your
fish tank with that little bubbler thing. Mixing dissolved free oxygen
in with H2O is not the same thing as chemically binding O2 to H2.

 

Either air or a failed MC can both be pumped up. That is not a reliable
test.

 

Well, when this happened to my civic a while back, the master cylinder
seals were the problem. I was totally unable to pump the brakes to
stiffness at all, even after bleeding the air out. The mechanic suggested
to me that the inability to pump to stiffness combined with the bleeding
indicated the master cylinder seals. :-?