[R-390] Aluminum Cleaning

Thu Mar 24 19:42:03 EDT 2011

Hi,

 Tricloro etileno solution , what I hate, because I was forced to use it
many years ago by my chief at that time( 27 years ago) is risky also,
because when you did not work it carefully , what is very difficult, when is
warm, it get acid ( because the CL what with water convert in H2CL )( I am
not at all strong in chemie).

(Also is terrible for human and the environment (At that times that was not
take in consideration). 

The use of tricloro ethylene  was a very hard  experience in my work like a
new engineer, after powder painting with polyester a brass surface cleaned
with tricoloro ethylene , I began to have nice ugly  brown points under the
painting after several  weeks or more , this happened with the first run of
production of faucets ( my job) at that time.

Later I  started to clean all with alkaline  and acids water solutions , and
coating with gold that did not corroded so easy prior to the transparent
powder painting over it. Now we do all that with PVD (physical vacuum
deposition),that looks like gold but is not and is very hard and don't need
to be painted and did not corrode after 200 hours in a salt atmosphere.( Buy
the way a Pvd mashine is like a vacuum tube were the parts that receive the
coating ( less than Micron) are the anode of the tube).

Powder coating (polyester, epoxi, pulieritano ) are hygroscopic , all of the
absorve water and with time corrode the base of the metal.  One solution for
white power coating was a nickel plating before the powder painting.....it
helped to prevent oxidation of the base. Cars had those problems also at
that time...

I agree with Tisha, It is very important to rinse with neutral (PH7) water
(if exist), normal water, very carefully, but I would prefer after cleaning
in a dishwasher, what I think is a good idea, rinse with water, then put all
in a solution of water and vinegar (acetic acid) to get all the alkaline
residues out, and again rinse with water very carefully and many times.
Acetic acid is not strong and in a low % solution will eliminated all
alkaline residues and then rinsed with water I think will work. Also
problems in metals are holes that we don't see, and if this holes are filled
with alkaline or acid spots will appear later.... That's way is good to
clean with hot water and good mechanical help, to instead to have acid or
alkaline residues in this hole we have water, that when they dry did not
really affect the surface to much. 

You can clean also aluminum with the juice of a Limon (it was mentioned
earlier in this forum). It is a good way to clean a metal surface also; it
is acid...but not strong at all.

Cleaning is still a very difficult process in galvanic! And every metal you
clean what you are doing is taking out not only oils or dirty thinks you are
taking out  part of the surface that was corroded, this corrosion help to
stop the corrosion in the case of aluminum and brass, it is not the case
like I mentioned first for  normal steel.

I am still working in a faucet company and all what is new nice looking
surface gave us a lot of problems, the best is the Chrome finish... but  if
we think in the environment we should accept that metal corrode and then
they keep in that way for years without problems for nobody.  

I have here 4 R390a, sitting to be improve.

No more storrys, sorry, It happen today that my wife is not home....

Thanks,

Francisco lu3eec

-----Mensaje original-----
De: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net] En
nombre de Tisha Hayes
Enviado el: Thursday, March 24, 2011 7:28 PM
Para: r-390 at mailman.qth.net
Asunto: [R-390] Aluminum Cleaning

While I do use the dishwasher for most everything (not the cats) I had not

really thought of the pH. Thanks to Francisco and others for pointing that

out.

Without applying it to "radio" and more to "kitchen" I have used "Cream of

Tartar" (tartaric acid) to polish up aluminum. Normally it is used for

making meringue as in lemon meringue pie.

I am reticent to deliberately doing alkaline <-> acid things to electronics.

That is probably one of the top benefits of things like Simple Green and

distilled water.

'long time ago I was tasked with figuring out the potential for corrosion on

circuit boards we fabricated. They had solder masks but we did not do

conformal coating. What brought it to management's attention was after the

folks in the panel fab area left an entire tray of circuit boards immersed

in the boiling side of a solvent cleaning tank all night long. (trichloro

type solution). We had other issues where the circuit boards were installed

in an enclosure, sealed with silicone RTV that releases acetic acid as it

cures (vinegar smell), those corroded as well*.

Tisha

***

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