A documentation of my first time Etching a knife, I used ferric Chloride I bought on eBay on my spyderco endura 4.

Step 1: Preparation

Start by disassembling your knife, using a T8 torx head for the pivot screw and a T6 for the rest - this size is pretty hard to come by but you can get them on amazon for less than £3. I used a flat head screwdriver and that worked but it did chew up one of the screws, luckily I could still take the knife apart.
Next take some nail polish and paint the areas you don't want to be etched (all contact areas - pivot, lock etc...) then if you choose to use the nail polish to paint a design. I didn't at first but I cant remember what I was thinking at the time. Use a cloth and some lighter fluid to remove any last grease from the blade before Etching.

Step 2: Etching

So my first tests, using 40% concentration ferric Chloride for 30 minutes I took the blade and clip out of the acid. I wanted a very dark, stone washed kind of effect but after sanding lightly with 1200 grit I was left with a matte grey all over which I was not happy with. I sanded it down as good as I could get it and started again. (you can use the acid a bunch of times before it loses its properties so there was no problem there)

Step 3: Attempt 2

I chose to do some nice stripes for the second attempt, I learnt that Etching isnt as obvious as I imagined and it only looks good on a surface with a comparison, so after sanding down the old etch to 1200 grit I applied nail polish on the contact points and painted on my design.
Lighter fluid and a rag to clean the blade and clip then back into the acid, this time I took the clip out at 45 minutes, this was not enough time, I'm guessing because of the type of steel but the etch was very faint. However the blade I left in for an hour and that worked perfectly.

Step 4: Polish, Reassemble and Resharpen

I took out the blade and clip, used acetone to get rid of the nail paint and looked at my results, the looked alot deeper than last time and the contrast was much more easily seen, sanding and buffing makes the contrast even more clear and I thought it looked great.
I then resharpened the edge up to mirror polish and oiled the pivot area.
I would recommend this as an easy knife customisation and I will be doing it alot more in the future, thanks for reading and good luck!