In this case, I had made a set of handlebar riser extensions for my motorcycle and wanted something stylish to finish them off, oh, and also fill those nasty holes ...
This instructable is based in part on techiques I found on the web, plus some of my own experimentation. A different approach can be found at: http://www.instructables.com/id/How-to-etch-aluminum-panel-labelsdesigns-with-a-r/
Step 1: Things you will need
The first thing you need is an idea of what you want to achieve! I wanted to make a couple of polished aluminium buttons to fill the holes in my handlebar risers, but you will probably want something different. Basically, the thing that you are going to apply your etched artwork to has to be made of aluminium, or some other metal that will etch well with acid.
So, the list looks something like this:
- The thing you want to etch
- wet and dry sandpaper (various grades from about 100 to 1200 grit)
- Brasso or similar polishing compound (or a buffing wheel)
- A laser printer
- A sheet of printer labels, minus the labels (i.e just the waxed backing sheet that you would normally throw away)
- A clothes iron
- some sticky tape (sellotape or similar)
- a couple of facial tissues
- disposable (latex) gloves
- 2 small artists brushes
- nail polish
- Acid - hydrochloric or sulfuric (Lemon juice might work as well)
SAFETY NOTE: Concentrated acids can be dangerous! At a minimum, observe the following:
- WEAR PROTECTIVE CLOTHING. Gloves and eye protection are a minimum.
- ALWAYS WEAR EYE PROTECTION when working with dangerous substances such as acid. You only have two eyes, and they are very sensitive to any sort of injury, much more so than your hands.
- NEVER ADD WATER TO ACID. If you need to dilute acid, add the acid to water. If you splash water with a little acid in it, it won't hurt you, but if you splash acid it WILL.
- WORK WITH SMALL AMOUNTS and keep the bottle capped. A small spill is easy to neutralise by flooding it with water. A large spill will ruin your whole year!
- DON'T BREATHE THE FUMES. The fumes from this reaction contain hydrogen and gaseous hydrogen chloride, both of which are bad to breathe in.
- Work on a flat surface clear of clutter, preferably somwhere you can flood with water if you need to. A kitchen sink or a laundry tub is not a bad choice.
Alright. Now that I've told you what not to do, let's get on with the fun stuff ...
Step 2: Make your part
You will need something to etch. I made up a couple of aluminium buttons from round bar, then sanded and polished the faces, You don't need a buff to get a good polished surface, but it does make it a LOT easier!
It is also worth noting that you don't HAVE to have a hightly polished surface, but the surface should be fairly flat and even and without gouges and large scratches.
To get a nice mirror finish by hand, rub the part down with wet and dry sandpaper going from coarse grit (100 grit or so) through successively finer grits till you get to 1200 grit. Clean the part between grits to avoid scratches, and rub each finer grit at an angle to the previous one. When all the previous grit marks are gone it's time to clean the part and move on to the next finer grit.
Once you have reached 1200 grit, use some brasso or a similar abrasive cleaning solution to polish the part.
If you have a buff, the process is a lot quicker. rub the part back with 600 grit then 1200 grit, then use a sisal buff to cut and finally a cloth buff to finish. As before, clean the part with acetone or similar between grits.
Step 3: Create the image
I then reduced the size of the image and made up an A4 sheet of logos using Open Office Impress. You can use powerpoint, or word, or staroffice, or any one of a number of programs to make up the sheet. I turned the page ruler on in Impress so that I could reduce the image to the right size, then duplicated the logo a number of times until I had a sheet full. You will want to print a sheet of images out because you probably won't get the next step (that's step 4) right the first time.
Next, I took the backing from a sheet of printer labels and removed the remaining sticky paper (the sticky paper bit between the labels). The labels themselves had been used for a bulk mail-out, and the waxed paper backing was left over. Normally the backing paper would go into the bin, but I saved it for exactly this kind of thing. Leave a strip (about 1/4") of the sticky paper on the top of the page for the laser printer to grab onto, but remove the rest.
Now print the image onto the waxed side of the backing sheet, as if the labels were still there. The toner will form a nice image on the waxed paper. I found that a colour laser is better for this, but if you only have a black-and-white printer, turn the toner density up as high as it will go. You may be able to do this from the printer control menu when you print the images, or you might have to set the toner density from the front control panel onthe printer.
Step 4: Transfer the image
Put some facial tissue over the button AFTER you have taped the logo down. The slight sponginess of the tissue will help to even out the pressure on the paper and ensure the image is evenly transferred. Now turn the temperature setting on the iron to full and sit the iron on top of the tissue. You will probably have to do a little experimentation to determine the optimal amount of time to leave the iron on. Too long and the image will bleed and go fuzzy, too short and the toner won't transfer fully.
I sat the iron on the button while it was still cold, then turned it on and waited for it to heat up. Once the red "heating up" light on the iron went out, I waited another 10 seconds or so then took the iron off and let the whole thing cool.
Step 5: Touch up and etch
Once the nail polish is dry, use a small brush to apply the acid. BE VERY CAREFUL, acid is nasty stuff and will ruin your day along with your clothes. Only work with a small amount at a time and avoid breathing the fumes. There's no real need to work quickly, so take your time. Once the acid has been worked over all the areas that you wish to etch, wash the part off with lots of water. The chemistry is something like:
2Al + 6HCl => 2AlCl3 + 6H2
2AlCl3 + 3H2O => Al2O3 + 6HCl
I used full strength acid on this part, but you might want to dilute the acid 1:1 or 1:2 with water, particularly for larger areas.
When diluting the acid, always always ALWAYS add the acid to the water, NEVER the other way around. If you splash water with a little acid in it on yourself there's no real problem, but if you splash acid with a little water in it on yourself, you will be in a world of hurt. Some acids, particularly in very concentrated form, react violently when water is added to them. Adding the same concentrated acid to water does not cause the same violent reaction.
WEAR EYE PROTECTION!
Once you have etched and washed the part, dry it and clean the toner and nail polish off with acetone.
If you like, you can now use some automotive clear coat lacquer to give it a weatherproof coating.