My question in what actual strength of ferric chloride solution are you using in Damascus finishing? 29% is a more or less standard solution strength, as called for in lots of rust bluing and Damascus finishing solutions. And people refer to that or milder solutions in Damascus finishing. But what is the strength of the commonly available Radio Shack solution? My bottle also lists hydrochloric acid as an ingredient.

If I take my 29% solution and cut it 1:1 with water, my result is 14.5%, if I cut it 1:1 again I get 7.25%. But I don't know what the strength of the Radio Shack solution is from the bottle.

I don't remember enough chemistry to remember if more that 29 Grams will dissolve in 61cc of water.

It's basically the same as yours. As I recall, it might be 31%, near enough to not really matter. I believe it does not contain HCL. The problem with HCL in etching solutions is it's prone to after-rusting relativly fast. But, it is one of the two acids in Aqua Regia type rusting solutions.

Regards
Ken

Here's the RadioShed MSDS for their etch.
https://cdn.shopify.com/s/files/1/0953/5...314291674007590

It shows the Ferric Chloride % at anywhere from 30% to 60% (??) ...unless I read it wrong! wouldn;t be the first time.
The hydrochloric acid content is 1/10% to 1.0%

Kind of hard with that wide range of 30 to 60% to dilute it to anything specific.

The stuff I use I bought off of EvilBay some years back. It;s marked as a specific % soln,,forget what it is.
I use it diluted to about 3 or 4% for damascus finishing

I have bought 42& ferric chloride off EBay. Then just diluted to what ever strength required. I admit I write it down on paper and use a calculator to get the amount to dilute it by correct. I tried Jethro Bodine math but got my ought(s) messed up and ended up with a much stronger mix than I wanted.

Dennis,
When I was experimenting with this, I had corresponded with Dr. Gaddy. What was unclear was the actual strength of the FeCl He gave me percentages, but I didn't know they were based on starting with a Radio Shack circuit board etch which is only 41% FeCl

So my experiments finally fleshed out that one part 41% strength circuit board etch diluted at least 6 parts water will work with a 10 second dip and immediate water flush with a wet carding of 000 or 0000 steel wool. 8 parts water will give you a little more time in the etch dip.

Or about 6% actual FeCl strength. As Kuttler pointed out, 3-4% works. Stronger than 6% and dwell gets too short.

I think Bertram had gotten around to doing it and would have more experience than I by now.

Dennis,

Are we talking about Black & White or Brown & White? It's my experience that Brown & White requires longer etching times.

The RS solution does contain a small amount of HCL. I dilute it one more time than what you listed, down to around 3-4%.

Regards
Ken

I use Ferric Chloride 10% as a final wash to increase
contrast WHEN NEEDED. I think I use it more for tighter Damascus(3 and 4 rod) and not the laminated etc. 10% for me seems to be the maximum percentage needed.
When I use it, I wash the bbls and steel wool lightly to help contrast before the Logwood "bath". As mentioned in one of the other posts anything with HCL in it causes RUST.
However any chemical CL after the atomic symbol or compounds symbol is a salt of HCL and requires a nice bath of Baking Soda when you are finished to prevent after rusting.

And I think my math is a bit off, it should be 71 cc H2O, Oh well.