Ironically a fine gentleman just sent these instructions to me. Hope he dont mind me reposting it. If he does I hope he dont bring out the dolls
From Bookie:
To etch a blade t bring out the folds:
Straight lemon juice is my primary etchant of choice for almost all applications. I used to prefer Ferric Chloride, but have since found that more cycles of a much weaker etch produce much more striking results than fewer cycles of a stronger etch. And by the time I've diluted my FeCl down, I might as well just use lemon juice anyway. It's natural, smells good, and is safe on skin; whereas FeCl is none of those things. With lemon juice I also don't find the need to heat the solution or the blade, which keeps things nice and simple (and uniform).
Materials
-Dish Soap
-Lemons
-Ferric Chloride
-Paper Towels
-Old T-shirt
-Windex
-Goo-Gone Xtreme, Lighter Fluid, or Acetone
-Metal Polish or Lead-wipe gun cloth
Start with a blade that is in polish. You'll need to remove any original etched finish by performing a light hybrid polish, bringing your blade down to smooth, bare metal.
1. Clean your blade thoroughly by scrubbing it with grease-cutting soap. Rinse and dry with a paper towel. Then give it a wipe down with Goo-Gone Extreme, Lighter Fluid, or Acetone to remove any traces of oil. From this point forward, do not touch the blade with your bare fingers.
2. For the first one or two etch cycles, I use Ferric Chloride at full strength. This may sound crazy, but I have found that it creates a nice and even satin sheen over the surface of your blade that will better accept the lighter etch cycles to follow, and looks more like Nihonto. (This step is optional. If you choose to do it, just follow step 3 using FeCl instead of lemon juice. Be sure to follow with steps 4, 5 and 6 before moving to actual step 3.)
3. Squeeze 1-2 lemons into a bowl. Add a few drops of dish soap. Dip a folded paper towel in the solution, and start rubbing it all over your blade. Medium pressure. Both sides, the entire length. Just keep rubbing the solution up and down both sides of the blade. Re-dip as necessary. After 5-10 minutes, you will notice the blade getting dark and grey. You should also see the hamon area turning a lighter color than the rest of the blade. Continue until the whole blade is evenly and sufficiently dark, dull, and grey.
4. Once the blade is fully oxidized, halt the etch by neutralizing it with Windex. Wipe it dry.
5. Begin removing the neutralized oxides using metal polish or lead-wipe gun cloth. I have started using the latter exclusively. It really works great. The rule of thumb for metal polish is that Pikal leaves the whitest hamon, Mothers Mag and Aluminum Polish leaves the brightest surface finish but a more subtle hamon, and Flitz is somewhere in between. I avoid Simichrome because it is too abrasive. I find old t-shirts to work well for applying metal polish.
6. Once all the oxides are gone, your blade will be greasy from whatever polish you used. Wipe the residue off with a Windex soaked paper towel, followed by Goo-Gone, followed by a dry paper towel. Make sure you cut all the grease and get all of the residue off. Remember not to touch the blade with your bare fingers.
Repeat steps 3 through 6. Depending on your blade and the intensity of detail you desire, you might repeat this cycle as few as 2 times, or as many as 10. Each cycle usually takes about 15 minutes, all-in. You can always stop at step 6 and take as long a break as you want. Repeat your etch cycle (steps 3-6) enough times to achieve your desired etch intensity.
59 AF&AM
