Subject: Explain Anodizing

From: [email-masked] (Wayne Perrier)
Date: Fri, 8 Oct 1993 18:05:44 GMT

Hello all!  I would like to ask about the process
of anodizing aluminum, namely, how does the process
work, characteristics of the metal before and after
anodizing, and will the physical size of the part
change (ie, increase or decrease) after anodizing?
thanks a bunch!

--
regards,

Wayne Perrier    
([email-masked])

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From: rey@safn2 (M Reynolds McClatchey Jr)
Date: 9 Oct 93 17:24:26 GMT

> work, characteristics of the metal before and after
Make it anodic in 15% H2SO4. 17 VDC 12 amperes/sq ft.

> change (ie, increase or decrease) after anodizing?
The coating can be built to application dependent thicknesses.
.00008 in to .008 in.
The al oxide film grows outward the same amount as al is consumed from the
surface, so the rule is that the dimension increases 1/2 the coating
thickness.
.040 sheet al with .0005 film on both sides = .0405 final dimension.

We etch off .002 in before anodizing to start with a clean surface.
So typically the parts get smaller. We have anodized to a final
dimension. Many shops will.

Many cities have "Anodizing" in their yellow pages.

-- 
Reynolds McClatchey (Southern Aluminum Finishing Co, Atlanta, GA, USA)
Architectural Aluminum. Custom Fabrication. Paint, Powder Coating, Anodizing.
MCImail 414-2935  Voice 404-355-1560  Fax 404-350-0581
uunet!safn2!rey			KQ4TS				[email-masked]

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From: [email-masked] (Wayne Perrier)
Date: Sat, 9 Oct 1993 21:51:25 GMT

I also have some further questions about anodizing, the answers
to which may interest other readers of this newsgroup.  Firstly,
I've heard that metal can be anodized in different colours.  What
chemical compositions should be used for the various colours, and
does the final surface of differing colours have different
properties besides colour (hardness, etc).  Also, how much harder
does anodizing make the surface (if at all)?
thankx very much for your comments.

regards,

Wayne Perrier

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From: [email-masked] (Barry Sanders)
Date: 11 Oct 1993 03:58:56 GMT

Hello Frenz,

In an art history class I attended, we had a visiting metal artist who
showed us numerous pieces of aluminum sculpture.  I asked her detailed 
questions about the anodizing process she used.  Being under the 
impression that it required electricity and solution baths, I was quite
surprised when she told me: "There's this chemical stuff that you paint 
on the aluminum.  It opens up the pores of the metal. Then you 
just paint it with any old dye or ink and then you paint some other
stuff on it to close up the pores, and that's it."  I asked her what 
kind of dyes or inks, and she said she had used all kinds, even water
based ones. (?!?!)  I kept at her, certain that she was lying, but she
insisted that it was just that easy.  No electricity, she said. (!)

What process was she using?  Where can I get the "stuff that opens/closes
the 'pores' of the metal", if indeed that is roughly what is happening.
The pieces she displayed looked really great; with nice, even coloring and
a kind of satin finish.  Really pretty.

Follow up to this group or reply via e-mail to [email-masked]

Thanks,

Barry Sanders

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From: [email-masked] (David Jenkins)
Date: 11 Oct 1993 08:00:12 GMT

In article <[email-masked]>,
[email-masked] (Wayne Perrier) writes:
|> 
|> I also have some further questions about anodizing, the answers
|> to which may interest other readers of this newsgroup.  Firstly,
|> I've heard that metal can be anodized in different colours.  What
|> chemical compositions should be used for the various colours, and
|> does the final surface of differing colours have different
|> properties besides colour (hardness, etc).  Also, how much harder
|> does anodizing make the surface (if at all)?
|> thankx very much for your comments.
|> 
|> regards,
|> 
|> Wayne Perrier    
|> ([email-masked])
|> 
|> 

If I'm not mistaken (who, me?) anodizing is a process for getting an
even and carefully controlled layer of alumin(i)um oxide on your item.
This can then be dyed any colour you fancy, followed by lacquer for
protection.

-- 

David Jenkins

Todays programme has been brought to you by the letters 'A', 'D' and 
'F' and by the number 27...

---

From: [email-masked] (bill nelson)
Date: Mon, 11 Oct 1993 19:07:03 GMT

[email-masked] (Barry Sanders) writes:
: 
: In an art history class I attended, we had a visiting metal artist who
: showed us numerous pieces of aluminum sculpture.  I asked her detailed 
: questions about the anodizing process she used.  Being under the 
: impression that it required electricity and solution baths, I was quite
: surprised when she told me: "There's this chemical stuff that you paint 
: on the aluminum.  It opens up the pores of the metal. Then you 
: just paint it with any old dye or ink and then you paint some other
: stuff on it to close up the pores, and that's it."  I asked her what 
: kind of dyes or inks, and she said she had used all kinds, even water
: based ones. (?!?!)  I kept at her, certain that she was lying, but she
: insisted that it was just that easy.  No electricity, she said. (!)
: 
: What process was she using?  Where can I get the "stuff that opens/closes
: the 'pores' of the metal", if indeed that is roughly what is happening.
: The pieces she displayed looked really great; with nice, even coloring and
: a kind of satin finish.  Really pretty.

Sounds like she is just confused about what is happening - it certainly is
not as she said.

I suspect that she brushed on a chemical that oxidized (anodized) the 
metal. She then dyed the oxide and finally painted it with a clear overcoat
to protect the dyed surface.

I know of no chemicals that can "open and close pores in aluminum".

Bill