Blade etching advice please

Danbo

Danbo

Joined
Nov 28, 1999
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I have etched a few damascus blades before, as well as a few differentially hardened carbon steel blades, to bring out the temper line. I thought I had the process down fairly well.

Last night, I was etching 2 blades. One was damascus and the other was a clay hardened W2 blade that Nick Wheeler heat treated for me. The damascus blade was handrubbed to 600, but the W2 blade was only about 220 and still had some coarser scratches visible from the grinder(yeah, I know, I just wanted to see that line).

Instead of simply using hot water from the tap, I used filtered water and put it in the microwave for a few minutes until it was good and hot. Maybe too hot. After cleaning the blades in a warm solution of TSP and water, I dried them and put them into the solution of hot filtered water and Archer's etchant. Probably a little under 50% solution. When I say maybe the water was too hot, I mean the solution was actually bubbling when the blades went in. I didnt think the water was that hot, but the plastic cup I used was too hot to hold onto for more than a second or two needed to take it from the microwave to the table. The blades were allowed to stay in the solution for a few minutes, and then I took them out and wiped them down with clean paper towels and lightly wiped them down with 600 grit paper. This was done about 3 times.

The damascus blade, after sanding with 600 grit paper, seems ok. The W2 blade, however, is really rough looking and is very hard to sand on. I mean, I took a piece of 120 grit ceramic belt, and it barely takes any color off. It does nothing to the rough etched finish, not to mention the leftover coarse scratches from the initial grinding. I even took a piece of a new 80 grit Regaloy belt, and rubbed on it. That rough finish is still there! What did I do to this blade? Did my using boiling or near to boiling etching solution do this? The damascus blade took a good bit of cleaning up too, and seemed harder to finish.
 
Sounds like you had some really aggressive stuff there. I don't know about w-2, I've never worked with it before. But as far as etching damascus and 52100 blades to expose the pattern/temper line, I only use tap water and ferric chloride (5 to 1) at room temp. I soak the damascus blades for 10 minutes, clean up with 2000 grit and soak again, I do this until I get the exposure I want, usually 3 soaks. 52100 for the temper line exposure is just in and out, in and out until I get what I want. then I clean them up and usually wash the acid line out to where its really faint. I never did care for a grey, acid dipped blade, it always looks about half finished to me.

Bill
 
So, maybe the solution was too strong and the soak time too long? I don't know exactly what I did, but combat knives need to have this kind of ugly and durable finish on them. :)
 
Dan. You gave them a really deep etch with that 50% mix and boiling solution. You will need to take the blades back to 600 - 800 grit and reduce the ferric cloride to 4 or 5 to 1 and room temp. The filtered water is probally ok. I like distilled water. Steel wont get harder by etching but will seem that way because it will be slow getting back down past the deep etch. Put them back on the belt grinder if you cant get them smooth by hand. For the best temper line rub them down to 2000 then etch and hand polish or lightly buff.
 
I'm not an etch guy (still practicing), but FWIW:

Tap water is going to vary wildly from place to place. So no 2 people using a tap water mixture are going to come out the same. Plus all the dissolved minerals in tap water are going to take their toll. Some of the minerals in your tap water solution might include:

Arsenic
Chromium
Lead
Calcium
Magnesium
Iron
Manganese
...

This goes for bottled and filtered water too.

Also, I believe, tap water is a bit alkaline - again this will vary. So, tap water is going to reduce the acidity more than distilled.

So the only way we can compare results and recipes is if we are all talking distilled.

Just a thought.

Steve
 
If you had some fairly deep scratches before the etch the etch is just going to make them deeper and harder to get out plus more noticable. I'd go back to a 220 belt and work my way down from there. I've been doing short intervals in the etch now, 30 seconds and maybe up to a minute rubbing inbetween with 00000 steel wool. I bought a pumace brick yesterday and plan on crushing it and making it into powder and then into a paste and using that inbetween etches....
 
Ray, you can buy pumice and rottenstone that is already powdered from some woodworking supply houses- might save you some trouble.
 
Danbo you are correct in your assumption that the water was too hot.

The warmer water increases the aggressiveness of the ferric chloride. Normally you do not want the water more than about 75f.

Water temp was the #1 problem I had to deal with when I worked for Devin. I would get several calls a week from makers having trouble with the steel etching properly. Most had not bothered to read the instructions for the etch. After water temp came solution strength, either too weak or too strong. Normally Double High carbon needs a 5 parts water 1 part ferric chloride mix and the Double Stainless and Carbon Nickel mixes need a 50/50 mix. And lastly there are some that seem to think acid will last forever. I had one maker that had 10-year-old acid. That may be a decent age for Scotch but not ferric chloride. I normally make a fresh batch of acid for each batch of knives.

I've also found over the last 6 years that the type of water (distilled, purified, tap etc) has not really had much of an affect on the etchant.
 
Don, I cut about an 1/8 of the pumace brick off and got it turned into powder yesterday. It wasn't all that bad to do but thanks for the information.
 
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