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Step 11Etch the Metal Plates
To etch aluminum plates you only need some basic materials, a 12VDC power supply (a modified computer power supply or a car battery charger), a laser printer, an iron, some packing tape and some nail polish.
I used the toner transfer method to make a "resist" layer for etching. I started by creating a graphic in Illustrator (attached below). I put multiple copies of the same stencil on one page, because the printing step makes a lot of defective stencils. The patterns are mirror images so that they appear correct when transferred to the metal.
Print the stencils using a toner-based laser printer or photocopier, onto glossy photo paper. Note that it must absolutely be glossy paper (not satin finish!) or the toner won't transfer to the metal very well. I know. I learned this the hard way! Check the printout and select the best one. Chances are, you'll get maybe one or two that are actually usable. The others will have spots here and there where the toner didn't stick to the photo paper. Be careful when you handle the stencil, as it will flake off very easily (if it doesn't flake off easily, you won't get a good transfer)
Cut out the best stencil and place it face-down on the metal plate. I used Kapton tape (a special heat-resistant tape) to hold it in place, but it's not necessary. Then, place a sheet of ordinary paper on top. Some photo papers have a plastic backing that will melt onto the iron if allowed direct contact, which is why the regular paper is important.
With the iron set to medium-high (cotton setting in my case), apply heat to the stencil and metal for 4-5 minutes. For the first two minutes just hold the iron in place without moving it. After that, alternate moving and holding the iron. Try dragging the edge of the iron along the stencil to put extra point pressure on it, which will help the transfer process and squeeze out air bubbles. Make sure you cover the corners too; I found they were the hardest to get a good transfer.
When you're done fusing the stencil to the metal, turn off the iron and place a large, flat, heat-resistant object on the stencil and metal as they cool. This is to prevent the photo paper from buckling before the toner has re-set. I used a glass 9x13 baking pan.
When the metal is cool you may peel off the photo paper. It should leave behind a shiny layer of black toner, hopefully with no voids or errors. Inspect the transfer carefully and correct any places where the toner did not transfer properly using nail polish.
To protect the back and sides of the metal plate from etching, cover them with ordinary packing tape. I like to stick a stripped wire to the back of the plate, so that I have someplace to attach the positive lead.
Now, head over to your etching tank. I used a plastic ice cream container filled with ordinary tap water and about 2 tablespoons of salt. You may also use washing soda; either will work. Place a piece of scrap aluminum on one side of the tank and attach the negative (black) lead to it. Then place the plate to be etched on the other side with the positive (red) lead attached. Connect the negative lead to the negative or ground connection on the power supply, and connect positive to the +12V line. When you flip on the power, you should see a cascade of bubbles emerge from the negative plate, and a smaller amount from the plate being etched. I assume these are hydrogen and oxygen, so please do this away from sources of spark and flame!
In 3-4 minutes the plate will be etched with a quarter-millimeter deep permanent pattern. Its gray matte finish contrasts nicely with the polished background. Peel off the tape, and clean off the nail polish and toner using nail polish remover. Wash in water, and you're done!
I used the toner transfer method to make a "resist" layer for etching. I started by creating a graphic in Illustrator (attached below). I put multiple copies of the same stencil on one page, because the printing step makes a lot of defective stencils. The patterns are mirror images so that they appear correct when transferred to the metal.
Print the stencils using a toner-based laser printer or photocopier, onto glossy photo paper. Note that it must absolutely be glossy paper (not satin finish!) or the toner won't transfer to the metal very well. I know. I learned this the hard way! Check the printout and select the best one. Chances are, you'll get maybe one or two that are actually usable. The others will have spots here and there where the toner didn't stick to the photo paper. Be careful when you handle the stencil, as it will flake off very easily (if it doesn't flake off easily, you won't get a good transfer)
Cut out the best stencil and place it face-down on the metal plate. I used Kapton tape (a special heat-resistant tape) to hold it in place, but it's not necessary. Then, place a sheet of ordinary paper on top. Some photo papers have a plastic backing that will melt onto the iron if allowed direct contact, which is why the regular paper is important.
With the iron set to medium-high (cotton setting in my case), apply heat to the stencil and metal for 4-5 minutes. For the first two minutes just hold the iron in place without moving it. After that, alternate moving and holding the iron. Try dragging the edge of the iron along the stencil to put extra point pressure on it, which will help the transfer process and squeeze out air bubbles. Make sure you cover the corners too; I found they were the hardest to get a good transfer.
When you're done fusing the stencil to the metal, turn off the iron and place a large, flat, heat-resistant object on the stencil and metal as they cool. This is to prevent the photo paper from buckling before the toner has re-set. I used a glass 9x13 baking pan.
When the metal is cool you may peel off the photo paper. It should leave behind a shiny layer of black toner, hopefully with no voids or errors. Inspect the transfer carefully and correct any places where the toner did not transfer properly using nail polish.
To protect the back and sides of the metal plate from etching, cover them with ordinary packing tape. I like to stick a stripped wire to the back of the plate, so that I have someplace to attach the positive lead.
Now, head over to your etching tank. I used a plastic ice cream container filled with ordinary tap water and about 2 tablespoons of salt. You may also use washing soda; either will work. Place a piece of scrap aluminum on one side of the tank and attach the negative (black) lead to it. Then place the plate to be etched on the other side with the positive (red) lead attached. Connect the negative lead to the negative or ground connection on the power supply, and connect positive to the +12V line. When you flip on the power, you should see a cascade of bubbles emerge from the negative plate, and a smaller amount from the plate being etched. I assume these are hydrogen and oxygen, so please do this away from sources of spark and flame!
In 3-4 minutes the plate will be etched with a quarter-millimeter deep permanent pattern. Its gray matte finish contrasts nicely with the polished background. Peel off the tape, and clean off the nail polish and toner using nail polish remover. Wash in water, and you're done!
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