how to bring out temper line?

C

coolhandluke4

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Jan 2, 2010
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Hey, I was wondering how you guys bring out the temper line on your differentially treated blades? I had read you could dip in, can't remember the name of the stuff, same stuff you get from Radio Shack to etch damascus.
Well, my first attempt failed dismally. Etching it brought out the temper line, and I went over it with OOOO steel wool. For whatever reason it got huge scratches in the tempered area in line with the way I went with the steel wool. So I put the knife in my vice and did the 90 degree bend test. On a good note, the blade survived and didn't shatter.
So, what's the best way to bring out the temper line?
 
You had the right idea with etching in ferric chloride. Generally the etchant is made by diluting the ferric chloride 3 to 1 with distilled water. DO NOT add any vinegar! It will "kill" the etchant.

From what you described, the "scratches", my guess is that the blade was not cleaned well enough prior to etching. To get a good etch and bring out the temper line, the blade should be finely handed sanded to at least 600 grit, and then the key.....CLEAN. That means putting on a pair of latex gloves, then cleaning the blade with something like acetone, and making sure it is absolutely clean. ANY residue, or oil, dirt, or even body oils of any kind and you will get streaks, or blotches, that can look like scratches when your done.

My process is the put on the latex gloves, clean the blade well with acetone, then clean it again with windex. Ensure the blade is 100% dry after the windex. (If you get windex into the etchant it will "kill" the etchant) I then lower the blade into the etchant, and then leave it there for a 10 count. I then pull the blade out and look at it. You will be able to see if everything is etching evenly. If you see streaks, spots, or blotches, the blade wasn't cleaned well enough. In most cases you could clean the blade again, and then try the etch again. If you leave the blade in much longer than a 10 count, it's likely that you will have to re-hand sand it. The whole key is that the blade is CLEAN prior to etching. ANY contaminate will cause streaks, spots, etc.
 
I do a very similar process to what Ed has described. When I initially put the blade into the etch I give it about 5 seconds bring it out and scrub it with 1500 grit. This will remove any possible remnants of contaminants from the blade. For a hamon, several light etches are better than heavy ones. I have even gone as far as applying the etch with a cotton swab and then polishing the blade with pumice stone or flitz.. This helps bring out the activity and may require 5-10+ etch polish processes.
 
So much just depends on the steel that's why W-2 is so popular. Normally the temperline or hamon shows up with the first 50 grit grind. After I finish hand rubbing the blade I just rinse the blade off with clean water and go in then etch while the blade is still wet and always have good results. Like Chuck said usually several quick etches are better than long etches. Funny there must be a shortage of Fc with the prices Radio Shack is getting for there pints now.
 
I picked up a gallon of FC at the local electronics store. It was about $30, much cheaper than the shack.
 
yeah, ferric chloride, that's the stuff, just couldn't remember the name last night.
The scratches were actual scratches. They were short, probably 3/16" long, going the length of the blade. It probably didn't help that I got distracted and left the blade in there for 20 minutes:rolleyes: I know they weren't there before etching because I had machine finished it to 2000 grit
Would the ferric chloride eat into the more hardened part enough to cause those scratches?

I'll give it another try and actually pay attention to what I'm doing. Does it need to be hand finished, or could I just machine finish it to 1000 grit and etch after that?
 
If the ferric etched scratches into the blade, then I'm fairly certain they were there prior to the etch. I'm not doubting your word, but the red flag went up when you mentioned "machine finish". Its very easy to miss some scratches if your trying to etch from a machine finish. I use the term "shadow scratches" to describe it to students....its the leftovers of heavier grit scratches that remain, even when you machine finish down as fine as you mentioned... and are very hard to see, even with strong light. After machine finishing, I always hand sand any blade that getting etched, at angles to the machine finish, until I can find no trace of any leftover scratches....even then I sometimes miss some, and after that initial 10 count in the etch, have to hand sand some more.

If there are actual scratches in a blade after it's been etched, then either they were there before the etch, or you could have possibly "scraped" the blade on the side/edge of that etchant tank.....thats all it takes. Even the tiniest scratch is accentuated by the etch.
 
coolhandluke4 said:
For whatever reason it got huge scratches in the tempered area in line with the way I went with the steel wool

The scratches were actual scratches.
I know they weren't there before etching because I had machine finished it to 2000 grit
Click to expand...

How are you storing your steel wool?

Is it possible that it got contaminated with some large grit particles from other abrasives, or your grinder.

I love tupperware / rubbermaid plastic containers for stuff...still need more.
 
For those that are not able to get FC

You can always use clear vinegar from your local grocery store, if you warm the vinegar up it seems to etch better
 
As Ed said, the start of those scratches was probably there before the acid etched them larger.
One reason that you try and not etch for 20 minutes continuously is the chance of creating etched lines in the blade. The acid forms tiny bubbles or convection currents that rise, and etch a line up the vertically suspended blade. If there is any minute scratch already there, it will use that as a path to follow, thus making them much larger and deeper. To prevent this, on long etches, you should take the blade out every few minutes, rinse it off, and wipe it down with degreased 4/0 steel wool or a pink 3M polishing cloth, rinse well, and return to the FC tank.

Another way to avoid severe etching on long soaks is to use a less active etchant. For developing the hamon or other similar lines, FC diluted 15:1, white vinegar diluted 4:1, or nitric acid diluted 100:1 work well.
These can be worked with rubber gloved hands and a soft cotton pad ( outside or in the shop obviously). You suspend the blade surface in the etchant for a few minutes, pull it out, and rub the area you are trying to bring out with the wetted pad. Work the hamon area for a few minutes by hand, and then re-submerge the blade for a minute or two. It can take many cycles of this to bring out the hamon, but all the time you are watching and helping it along. There is seldom a problem with this procedure.

Stacy
 
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