cleaning ferric cloride

[insanity]

I will start this by saying I have not tried this on a knife yet, but that said this information is from a master printer at Pace Editions. This is what he uses to clean copper plates that have been etched with ferric cloride. After the etch he uses a slurry vinegar and salt (NaCl) to lightly scrub the plate with. Then rinses with clean water. The reason for this is that the ferric leaves a precipitate on the metal that will continue to corrode it over time. This is not easily washed off with water. The vinegar (being a diluted weak acid) acts as a release for the precipitate. The salt helps as a gentle scrubbing agent.

I remembered a thread a little while back discussing if vinegar neutralized ferric cloride or not and thought I'ld pass this on.

WS

 

[WinDancer]

Most of the makers I know use baking soda with a soft brush. I have been using it for the past year with good results.

Dave

 

[Will52100]

Windex, folowed by a scrub with bakeing soda, no rust yet, been etching for a couple of years now. The windex has amonia, and neutralizes the feric. You know it's working when you spray it on and it turns green.

 

[Ed Fowler]

I sue a super asturated solution of TSP - Tri soduim phosphate, then to the buffer.

 

[misque]

Double post. I hate it when that happens.

 

[misque]

Ed,
I'm using TSP dissolved in water and then to the buffer, but several days afterward, I'm getting what looks like a residual etching action on the blade.
Are you heating your water before adding TSP or something else to get a "super saturated solution"? Is yours more of a paste maybe? I'm dissolving as much as I can in tap water and just can't seem to get all the etchant off.
Also, how long can this solution be used before replacing it?

 

[etp777]

Not claiming to know what Ed is doing, or necessarily even what he meant, but yes, to super saturate a solution, heat the liquid(can dissolve more of the soluble material in it if it's hot than cold, with most solutions), and then let it cool down. This allows more of the TSP in the water than you would normally get at that temperature, as it will stay dissolved in the solution, at leas tfor a while, at the cooler temperature. It will generally precipitate out eventually, but shouldn't be of concern in just cleaning up after an etch.

 

[Ed Fowler]

I have not seen what you describe. Don't know why, Sometimes if your TSP solution is too strong, it will neutralize the ferric chloride then do some etching on its own. This happened to some blades when I had a couple of inches of undisolved TSP in the botttom of my TSP jar. I do not heat my water, just poured in TSP, a little more than would desolve. I take the blade out of the ferric chloride, let it drip back some, then into the TSP, hold it there for a few seconds, then wipe it dry and as clean as a paper towel can do, then into some water with a very little Ivory Soap in it. Then to the buffer, then coat with Break Free and wrap it with a paper towel that I secure around the blade with making tape for a work sheath. I clean and refresh the TSP jar every couple of years or more. Could it be that you spilled something in the area where you store the blades? The fumes from the residue could be doing some etching on their own.