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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 |
#2
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"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
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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
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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 |
#5
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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
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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
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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! |
#8
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#9
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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 |
#10
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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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