I got a terrible looking fuzzy etch on a blade I finished this AM. High carbon Damascus, heat treated and finished to 400 grit. Ferric chloride is the etchant - it is a couple of years old.... I did a single dunk for 10 minutes or so. Other blades I've done recently this way came out OK, so I don't know what happened .... Any help appreciated.
Rebecca

Hello:

what materails did you weld to what?? If it's a high C/Low C mix you might have some carbon migration going on...that can cause the "fuzzy" look..but I need to know what you welded up in order to be of any help..

JPH

Well, the fact that recent blades came out OK notwithstanding, etchant that old is way too old to reliably provide good results. A lot depends on what steels are in the damascus but I rarely get good results with an etch as long as 10 minutes although I know that in some cases that does work. My etches tend to run anywhere from 15 seconds to maybe 5 minutes, usually done on 15 - 30 second intervals with a rinse each time to check the progress.

Finally, if the etchant isn't the problem the heat treat of the steel can be. There are too many variables that could have caused a coarse grain structure but the bottom line is, if the grain structure is coarse the etch will come out fuzzy...

I suspect the culprit that caused the fuzzy edge is that your etchant is too strong. When you say that FC was the etchant do you mean that it was straight, undilluted acid? Your FC should be cut with distilled water....usually 1 part FC to at least 2 parts water. Even if it was cut it may have lost some of the water due to condensation.

I've gotten great results using 1 part FC, 2 parts distilled water, 1 part white vinegar. The vinegar slows down the action and I wind up with really nice clean etches.

I prefer deep etches...I like to be able to run my fingernail over the steel and feel the etch. Using the ratio described above, depending on the response I'm getting from the steel, I usually dunk about 4 times at 4-5 minutes per dunk. After each dunk I scrub with an old toothbrush (to clear out any loose, etched oxides) while rinsing in running, purified tap water, and then I dunk again, repeating the process until I achieve the desired results. Sometimes I will also immerse the steel in boiling water and baking soda. I read somewhere several years ago that the boiling water and baking soda helps to set the dark oxides....it seems to help. When finished I spray down the steel with acetone to remove all water (to avoid overnight rusting) and then cover with a light amount of wax (I usually use Rennaisance wax).

Overall you don't want your acid to be too strong...When it comes to etching stronger is not better as it will tend to cut all the metals at a similar rate and you wind up with a fuzzy etch.

BTW- I too save my etchant solutions... in a sealed plastic container. I have three containers that vary in strength and they're 1-4 years old. But even stored in the sealed containers, when I go to open them again I can tell that I seem to loose a little liquid every time it's been sitting for awhile... so I always add a little bit of water, acid, and vinegar in equal amounts each time I go to use it agin. Could be my imagination but my etches seem to just be getting better and better. ;-)


Dennis Greenbaum

I realized when I posted this how many different variables were in play. The steel is Thunderforge Damascus from Texas Knifemakers. The etchant is the stuff from Radio Shack, with 50% dilution with regular tapwater. I keep it in a sealed plastic jug, but I'm sure some of the H2O has evaporated. Thanks for the suggestions. I think I need to get some new etchant; dilute it more and with distilled H2O; and use a much shorter etch time, several cycles if necessary.
Thanks again.
Rebecca

Rebecca:

I have no idea as to what these fellows are welding and apparently neither do you, so we are both in the dark on this. Have you contacted the Thunder folks and asked them???

On the etch.. I also use ferric chloridfe but I etch for at least 60 to 90 minutes using a 4 to 1 water to FC mix. This gives me a nice, even etch, decent topography and it isn't as "agressive" as a quicker etch..to me (as I have said many times before..) a slow etch is a beautiful etch...plus if something does "go wrong" the "damage" is minimal...

JPH

Everyone keeps saying 1 part FC to 2-3 parts water. That's assuming the FC is already liquid. What is the ratio if it's in powder form?

Ed