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In article <1144213703.375687.127290@v46g2000cwv.googlegroups.com>,
"Andrew Sarangan" <asarangan@yahoo.com> wrote:
> I'm using the following steps for treating my aluminum parts:
>
> - scrub clean with Acetone and scotchbrite
> - dry
> - scrub clean in Metalprep-79 and scotchbrite
> - rinse in water
> - repeat until water forms smooth sheet (water break test)
> - dip in alodine 1201 until part turns golden brown
> - rise in water
>
> After the final rinse, the golden brown coating feels soft and
> delicate, and could be rubbed off easily. I've to hang the part and
> let it completely dry before touching it.
Golden brown is too much! All you need for best results is a light
golden hue. Keeping it in the Alodine too long actually reduces the
corrosion protection! About 10 - 20 minutes immersion should suffice.
> Now, I can remove the alodine by scrubbing the part again with
> Metalprep-79 and recover its original shiny surface. If it repeat the
> above surface treatment all over again, I get a more stable coating
> that looks more uniform and not so soft, and also appears slightly
> darker in color.
>
> I'm not sure if I understand why this is happening. This has happened
> every time I tried it, not just once, so it isn't a random occurence.
> Why is the re-coat giving me better results than the first-time coat?
You can also use a weak mixture of lye and water as a prep. For best
results, heat it to 120 deg F and dip the part for about 5 minutes.
Yes -- the aluminum must be free of dirt and grease befor starting the
process.
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Re: Question about Alodine 1201
