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Old July 16th 05, 01:30 AM
RadioGuy
 
Posts: n/a
Default Finishing Aluminum

Howdy:

Its been a common practice with me to finish the aluminum surface of a
chassis or box with an immersion into a caustic solution followed with a
coating of clear acrylic spray---I like the satin finish it produces. I
normally use lye that I regularly found on the shelves of our neighborhood
hardware stores. However, I've been having a harder time of finding the
flaked lye that I have used over the years for that purpose. I have used
'Lewis Red Devil Lye' that I found at Ace Hardware.

A project that I am currently working on made me think of trying a
substitute for lye with an item that I seem to find everywhere. Often found
in the automotive stores is a product that is referred to as a
'cleaner/degreaser' or 'heavy duty industrial cleaner'. I have seen it
marketed as 'Purple Stuff' yet I purchased a gallon called 'Right Stuff
(Purple Stuff Concentrate)' manufactured by Sunbelt Chemicals, Palm Coast,
Florida, 386.446.4595. Nevertheless, the contents of both bottles have a
characteristic purple color and contains (besides sodium hydroxide) a
component derived from citrus---but more importantly, the label states that
the product is NOT TO BE USED ON ALUMINUM!

I finished the surface of both halves of a mini-box by immersing them into a
solution, by volume, of 1 part 'Right Stuff' to 8 parts warm water (I used
1:8 for no particular reason---It just happened that way). The surface of
the aluminum began to bubble rapidly, but not uncontrollably, causing a fine
white froth to appear on the surface of the solution. I let the mini-box
soak for 30 minutes whereupon I removed them and placed them into a bucket
of water. I found that the removal of the black residue is easier to
achieve if I wash the aluminum parts while they remain under water---a
sponge or cloth works fine and a Q-Tip removes the residue from corners. I
observed that as the reaction proceeded the purple color of the solution
became clear.

Needless to say, I am entirely satisfied with the results. The dilute
solution of 'Right Stuff' provided a uniform satin finish identical in
appearance to a solution of lye (sodium hydroxide). If you can't find lye I
suggest a solution of industrial cleaner possessing caustic properties. The
next time I use 'Right Stuff' I will increase it by 1 part just to see the
result. The reaction liberates hydrogen gas---use adequate ventilation.

RG



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Old July 16th 05, 02:01 PM
Roger Conroy
 
Posts: n/a
Default


"RadioGuy" wrote in message
...
Howdy:

Its been a common practice with me to finish the aluminum surface of a
chassis or box with an immersion into a caustic solution followed with a
coating of clear acrylic spray---I like the satin finish it produces. I
normally use lye that I regularly found on the shelves of our neighborhood
hardware stores. However, I've been having a harder time of finding the
flaked lye that I have used over the years for that purpose. I have used
'Lewis Red Devil Lye' that I found at Ace Hardware.

A project that I am currently working on made me think of trying a
substitute for lye with an item that I seem to find everywhere. Often
found
in the automotive stores is a product that is referred to as a
'cleaner/degreaser' or 'heavy duty industrial cleaner'. I have seen it
marketed as 'Purple Stuff' yet I purchased a gallon called 'Right Stuff
(Purple Stuff Concentrate)' manufactured by Sunbelt Chemicals, Palm Coast,
Florida, 386.446.4595. Nevertheless, the contents of both bottles have a
characteristic purple color and contains (besides sodium hydroxide) a
component derived from citrus---but more importantly, the label states
that
the product is NOT TO BE USED ON ALUMINUM!

I finished the surface of both halves of a mini-box by immersing them into
a
solution, by volume, of 1 part 'Right Stuff' to 8 parts warm water (I used
1:8 for no particular reason---It just happened that way). The surface of
the aluminum began to bubble rapidly, but not uncontrollably, causing a
fine
white froth to appear on the surface of the solution. I let the mini-box
soak for 30 minutes whereupon I removed them and placed them into a bucket
of water. I found that the removal of the black residue is easier to
achieve if I wash the aluminum parts while they remain under water---a
sponge or cloth works fine and a Q-Tip removes the residue from corners.
I
observed that as the reaction proceeded the purple color of the solution
became clear.

Needless to say, I am entirely satisfied with the results. The dilute
solution of 'Right Stuff' provided a uniform satin finish identical in
appearance to a solution of lye (sodium hydroxide). If you can't find lye
I
suggest a solution of industrial cleaner possessing caustic properties.
The
next time I use 'Right Stuff' I will increase it by 1 part just to see the
result. The reaction liberates hydrogen gas---use adequate ventilation.

RG



Has anyone ever tried mag wheel cleaner? It's specifically intende for use
on Al/Mg Alloys.



  #3   Report Post  
Old July 16th 05, 03:22 PM
Wes Stewart
 
Posts: n/a
Default

On Sat, 16 Jul 2005 00:30:33 GMT, "RadioGuy"
wrote:

Howdy:

Its been a common practice with me to finish the aluminum surface of a
chassis or box with an immersion into a caustic solution followed with a
coating of clear acrylic spray---I like the satin finish it produces. I
normally use lye that I regularly found on the shelves of our neighborhood
hardware stores. However, I've been having a harder time of finding the
flaked lye that I have used over the years for that purpose. I have used
'Lewis Red Devil Lye' that I found at Ace Hardware.


I still have a couple of cans of Red Devil "in stock" after my last
project. That was the rejuvenation of a 20-year-old Yagi antenna. I
built a plastic sheet lined trough outside that was long enough to
hold the longest piece of tubing and had at it.


A project that I am currently working on made me think of trying a
substitute for lye with an item that I seem to find everywhere. Often found
in the automotive stores is a product that is referred to as a
'cleaner/degreaser' or 'heavy duty industrial cleaner'. I have seen it
marketed as 'Purple Stuff' yet I purchased a gallon called 'Right Stuff
(Purple Stuff Concentrate)' manufactured by Sunbelt Chemicals, Palm Coast,
Florida, 386.446.4595. Nevertheless, the contents of both bottles have a
characteristic purple color and contains (besides sodium hydroxide) a
component derived from citrus---but more importantly, the label states that
the product is NOT TO BE USED ON ALUMINUM!

I finished the surface of both halves of a mini-box by immersing them into a
solution, by volume, of 1 part 'Right Stuff' to 8 parts warm water (I used
1:8 for no particular reason---It just happened that way). The surface of
the aluminum began to bubble rapidly, but not uncontrollably, causing a fine
white froth to appear on the surface of the solution. I let the mini-box
soak for 30 minutes whereupon I removed them and placed them into a bucket
of water. I found that the removal of the black residue is easier to
achieve if I wash the aluminum parts while they remain under water---a
sponge or cloth works fine and a Q-Tip removes the residue from corners. I
observed that as the reaction proceeded the purple color of the solution
became clear.


Good to know. You might find that a dip in vinegar will help with the
removal of the black smut.


Needless to say, I am entirely satisfied with the results. The dilute
solution of 'Right Stuff' provided a uniform satin finish identical in
appearance to a solution of lye (sodium hydroxide). If you can't find lye I
suggest a solution of industrial cleaner possessing caustic properties. The
next time I use 'Right Stuff' I will increase it by 1 part just to see the
result. The reaction liberates hydrogen gas---use adequate ventilation.


If you want a really satiny surface, another trick I have used is to
sand the surface with an orbital sander and medium grit wet-dry paper
lubricated with light oil. It's a messy process but leaves an
interesting surface with the little "orbit" scratches and it's a good
way to recover badly scratched surfaces. Etching afterwards with lye
"softens" the effect and of coarse cleans the surface.

  #4   Report Post  
Old July 16th 05, 05:40 PM
RadioGuy
 
Posts: n/a
Default


Wes Stewart wrote in message
...
On Sat, 16 Jul 2005 00:30:33 GMT, "RadioGuy"
wrote:

Howdy:

Its been a common practice with me to finish the aluminum surface of a
chassis or box with an immersion into a caustic solution followed with a
coating of clear acrylic spray---I like the satin finish it produces. I
normally use lye that I regularly found on the shelves of our

neighborhood
hardware stores. However, I've been having a harder time of finding the
flaked lye that I have used over the years for that purpose. I have used
'Lewis Red Devil Lye' that I found at Ace Hardware.


I still have a couple of cans of Red Devil "in stock" after my last
project. That was the rejuvenation of a 20-year-old Yagi antenna. I
built a plastic sheet lined trough outside that was long enough to
hold the longest piece of tubing and had at it.


I never thought of that for long pieces... thats a good tip.


A project that I am currently working on made me think of trying a
substitute for lye with an item that I seem to find everywhere. Often

found
in the automotive stores is a product that is referred to as a
'cleaner/degreaser' or 'heavy duty industrial cleaner'. I have seen it
marketed as 'Purple Stuff' yet I purchased a gallon called 'Right Stuff
(Purple Stuff Concentrate)' manufactured by Sunbelt Chemicals, Palm

Coast,
Florida, 386.446.4595. Nevertheless, the contents of both bottles have a
characteristic purple color and contains (besides sodium hydroxide) a
component derived from citrus---but more importantly, the label states

that
the product is NOT TO BE USED ON ALUMINUM!

I finished the surface of both halves of a mini-box by immersing them

into a
solution, by volume, of 1 part 'Right Stuff' to 8 parts warm water (I

used
1:8 for no particular reason---It just happened that way). The surface

of
the aluminum began to bubble rapidly, but not uncontrollably, causing a

fine
white froth to appear on the surface of the solution. I let the mini-box
soak for 30 minutes whereupon I removed them and placed them into a

bucket
of water. I found that the removal of the black residue is easier to
achieve if I wash the aluminum parts while they remain under water---a
sponge or cloth works fine and a Q-Tip removes the residue from corners.

I
observed that as the reaction proceeded the purple color of the solution
became clear.


Good to know. You might find that a dip in vinegar will help with the
removal of the black smut.


Thanks... I didn't know that! I often wondered if there was an easier way
to remove the black residue.


Needless to say, I am entirely satisfied with the results. The dilute
solution of 'Right Stuff' provided a uniform satin finish identical in
appearance to a solution of lye (sodium hydroxide). If you can't find

lye I
suggest a solution of industrial cleaner possessing caustic properties.

The
next time I use 'Right Stuff' I will increase it by 1 part just to see

the
result. The reaction liberates hydrogen gas---use adequate ventilation.


If you want a really satiny surface, another trick I have used is to
sand the surface with an orbital sander and medium grit wet-dry paper
lubricated with light oil. It's a messy process but leaves an
interesting surface with the little "orbit" scratches and it's a good
way to recover badly scratched surfaces. Etching afterwards with lye
"softens" the effect and of coarse cleans the surface.


I'll give that technique a try.


Awhile back I heard that after the metal is finished in a lye bath then
boiled in a solution of color dye (RIT) a colored, metallic finish, can be
produced---one of these days I'll try it on a scrap piece.

On simple projects I print or photocopy text then affix them onto to the
aluminum surface (after a first coat of acrylic on the aluminum) with white
glue then with multiple sprays of acrylic affix them permanently to the
surface. It worked real nice with a bandpass filter project---I secured the
graph of the filter characteristics onto the minibox for reference.

RG




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Old July 17th 05, 03:13 PM
Wes Stewart
 
Posts: n/a
Default

On Sat, 16 Jul 2005 16:40:27 GMT, "RadioGuy"
wrote:

[snip]

Good to know. You might find that a dip in vinegar will help with the
removal of the black smut.


Thanks... I didn't know that! I often wondered if there was an easier way
to remove the black residue.


Actually, a stronger acid works better (quicker). The "blackness"
seems to depend on the alloy and it may still take light rubbing to
get the stubborn stuff off. I'm neither a chemist or metalurgist but
in my early days in a real engineering lab environment we had a "chem
lab" where they had tanks of caustic and acid (and Alodine) for
passivating aluminum and I learned a few things there. Always
remember to fully rinse any of this stuff off with lots of water.

[snip]

Awhile back I heard that after the metal is finished in a lye bath then
boiled in a solution of color dye (RIT) a colored, metallic finish, can be
produced---one of these days I'll try it on a scrap piece.


Now you're starting into anodizing. See:

http://w3.uwyo.edu/~metal/anodizing.html

On simple projects I print or photocopy text then affix them onto to the
aluminum surface (after a first coat of acrylic on the aluminum) with white
glue then with multiple sprays of acrylic affix them permanently to the
surface. It worked real nice with a bandpass filter project---I secured the
graph of the filter characteristics onto the minibox for reference.


Nice idea. I use the ruboff lettering (Datak) but of course they
don't have any BPF response curves, [g]



  #6   Report Post  
Old July 17th 05, 03:16 PM
-ex-
 
Posts: n/a
Default

Wes Stewart wrote:
On Sat, 16 Jul 2005 16:40:27 GMT, "RadioGuy"



On simple projects I print or photocopy text then affix them onto to the
aluminum surface (after a first coat of acrylic on the aluminum) with white
glue then with multiple sprays of acrylic affix them permanently to the
surface. It worked real nice with a bandpass filter project---I secured the
graph of the filter characteristics onto the minibox for reference.



Nice idea. I use the ruboff lettering (Datak) but of course they
don't have any BPF response curves, [g]



On a bare metal panel the homebrew inkjet waterslide decals work quite
well and you could do your response curve with that method.

-Bill
  #7   Report Post  
Old July 17th 05, 05:46 PM
Dave Platt
 
Posts: n/a
Default

In article ,
Wes Stewart wrote:

Good to know. You might find that a dip in vinegar will help with the
removal of the black smut.


Thanks... I didn't know that! I often wondered if there was an easier way
to remove the black residue.


Actually, a stronger acid works better (quicker). The "blackness"
seems to depend on the alloy and it may still take light rubbing to
get the stubborn stuff off.


As I understand it, the black stuff is usually referred to as "smut".
It's the other metals in the alloy, left behind when the lye dissolves
the aluminum.

Anodizing shops will follow the lye-etch with a plunge into a "bright
dip" acid bath to de-smut the surface and leave it nice and shiny.
Bright dip mixtures seem to vary - one I've seen mentioned is mostly
phosphoric acid, with a few percent of nitric acid added. Kinda nasty
stuff.

Awhile back I heard that after the metal is finished in a lye bath then
boiled in a solution of color dye (RIT) a colored, metallic finish, can be
produced---one of these days I'll try it on a scrap piece.


Now you're starting into anodizing. See:

http://w3.uwyo.edu/~metal/anodizing.html


Yup. A common cycle seems to be: drill and sand, etch in lye,
bright-dip to de-smut, anodize to build up a porous layer of hard
aluminum oxide, boil in dye to color, seal.

One problem with the use of RIT color dyes is that they aren't all
that stable against UV, and can fade over time. There are
professional anodizing dyes which are more stable.

On simple projects I print or photocopy text then affix them onto to the
aluminum surface (after a first coat of acrylic on the aluminum) with white
glue then with multiple sprays of acrylic affix them permanently to the
surface. It worked real nice with a bandpass filter project---I secured the
graph of the filter characteristics onto the minibox for reference.


Nice idea. I use the ruboff lettering (Datak) but of course they
don't have any BPF response curves, [g]


The Brother plastic-laminated labelling tapes seem to work fairly
well, also. I usually use the standard black-text-on-white-background
and then spray with acrylic. The black-on-clear might look nice on an
aluminum case, but I haven't tries this myself yet.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
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Old July 19th 05, 12:22 AM
Larry Gagnon
 
Posts: n/a
Default

On Sat, 16 Jul 2005 00:30:33 +0000, RadioGuy wrote:

Howdy:

Its been a common practice with me to finish the aluminum surface of a
chassis or box with an immersion into a caustic solution followed with a
coating of clear acrylic spray---I like the satin finish it produces. I
normally use lye that I regularly found on the shelves of our neighborhood
hardware stores. However, I've been having a harder time of finding the
flaked lye that I have used over the years for that purpose. I have used
'Lewis Red Devil Lye' that I found at Ace Hardware.

[snip]

Am I correct in understanding that TSP, also called Sugar Soap (the stuff
used by many to wash walls before painting) is essentially mostly lye? If
so that is quite a cheap source you might want to consider.

Larry VE7EA
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Old July 19th 05, 12:36 AM
Dave Platt
 
Posts: n/a
Default

In article ,
Larry Gagnon wrote:

Am I correct in understanding that TSP, also called Sugar Soap (the stuff
used by many to wash walls before painting) is essentially mostly lye?


Nope. TSP is Tri-sodium phosphate. "TSP substitute" is apparently
often composed largely of sodium carbonate ("washing soda" or "soda ash").

I believe that both of these chemicals will attack aluminum, but that
the reactions are a lot slower than is the case with lye (sodium
hydroxide).

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!


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