Chemical/ Eletro Etching problem!!

C

Chris81

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Sep 27, 2018
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Hey there fellow Bladesmithy's...I was just gifted an electro etcher for Xmas, and I was super excited to start adding my touch mark to knives buuuuuttttttttt..... I am not getting a deep etch. I have a "knife dog,' KD-30 machine with SC-44 solution and a stencil from IMG. I have tried to etch two different knives: 1 made from a rasp and another made from 1095. I get a dark mark but I can just about wipe it off, then you can see a faint etch in the steel. I have tried different intensities and it just gets darker and not deep etch, I would like. What am I doing wrong? Should I be using a different electrolyte solution? If so, what?
Both of the knives are sanded up to 400 grit, washed with soap and water, then dried before I attempted to etch.
 
I haven't used the machine you mentioned. But in looking at photos of it, you have a switch for AC and DC. In general you want to alternate between the AC and DC as you are etching. On mine I hold for about a count of ten then switch to the other setting and count the same length of time. It depends on what steel I'm using as to how long I do this and for how many times. It takes a bit of experimentation, so I'd try it on a few scrap pieces of the same steel before trying your etch on the knives.

Something else you can do to help darken your etch is to 'fill-in' your mark after the etching is done. I use liquid gun bluing for that on my knives. Some people use a sharpie or similar. Again you might want to experiment on a scrap piece before attempting on a finished knife.
 
How long are you holding the handpiece on the stencil? Are you wiping the stencil or cotton every now and then to take off any contaminants? Start with DC for a few times at 10 - 20 seconds each with a pause between each for a deep etch and then switch to AC for a dark mark.
 
There are several common issues with etching:
1) Wrong polarity - Make sure the pad is attached to the negative terminal and the blade has the positive clip.
2) Wrong current - Etch on DC, mark on AC. Etch in pulses of 10-15 seconds. After three or four of those, switch to AC for 5 to 10 seconds ( test on scarp to determine exact times)
3) Wrong voltage/current - You need a unit capable of delivering 1 amp continuous at 12V. 12V/24V and 2 or 3 amps is even better.
4) Too much electrolyte - The pad should be just barely damp with the solution. It should be blotted on a folded paper towel just before applying over the stencil.
5) Too much voltage - If your unit has variable voltage start around 12 volts and do some tests. Too high voltage can "burn" the mark.
6) Wrong Electrolyte Solution - If the above parameters are right almost any electrolyte will work. The commercial ones do seem better, though.
 
seanj said:
In general you want to alternate between the AC and DC as you are etching. On mine I hold for about a count of ten then switch to the other setting and count the same length of time. It depends on what steel I'm using as to how long I do this and for how many times.
Click to expand...
That is a new process to me. I've always read use the DC first to get the depth for the etch. After 20 to 30 seconds of DC (lifting pad every 5 seconds or so to allow cooling and gas to escape), then switch to AC for 10 to 15 seconds or so to allow the etch to become dark. The AC should for sure be the very last step of etching.

Am I missing something?
 
yes, sounds like the OP was marking instead of etching. check the switch. etch first, then mark. mark is just the black coloring added to the etched stencil.
 
Ken H> said:
That is a new process to me. I've always read use the DC first to get the depth for the etch. After 20 to 30 seconds of DC (lifting pad every 5 seconds or so to allow cooling and gas to escape), then switch to AC for 10 to 15 seconds or so to allow the etch to become dark. The AC should for sure be the very last step of etching.

Am I missing something?
Click to expand...
Probably not. I could be wrong. But this has been working for me. My etcher is a home made one. Perhaps that's the difference.
 
Here is how etching works:
1)The ETCH is caused when DC moves through the blade, taking electrons and metallic ions in one direction. The current for etching is called "Reverse Current", which means the current is flowing from the blade to the pad. This pulls out metal ions and slowly erodes away the metal where the stencil leaves it exposed. The surface exposed is grayish metal. Under a microscope it looks like a million little craters. The pad gets the ions which oxidize there and usually make the pad black. How fast, crisp, and deep the etch is a factor of having the right combination of parameters ( see my earlier post #4).

Once the desired amount of metal has been removed, the recess needs to be made darker.

2) The MARK is made by using AC current. This changes direction 60 times a second, repeatedly removing and then re-depositing the ions in the bottom of the etch. Because this causes the metal ions to oxidize, the bottom turns black. The voltage and amperage as well as te amount of time will determine the quality of the MARK. Too much can start to "lift" the black out.

So, ETCH first with DC to remove the metal, then MARK with AC to blacken the etch.

One technical reason to not switch back and forth is that the oxides are somewhat non-conductive and may actually make the etching slow down or stop.
 
Stacy E. Apelt - Bladesmith said:
Here is how etching works:
1)The ETCH is caused when DC moves through the blade, taking electrons and metallic ions in one direction. The current for etching is called "Reverse Current", which means the current is flowing from the blade to the pad. This pulls out metal ions and slowly erodes away the metal where the stencil leaves it exposed. The surface exposed is grayish metal. Under a microscope it looks like a million little craters. The pad gets the ions which oxidize there and usually make the pad black. How fast, crisp, and deep the etch is a factor of having the right combination of parameters ( see my earlier post #4).

Once the desired amount of metal has been removed, the recess needs to be made darker.

2) The MARK is made by using AC current. This changes direction 60 times a second, repeatedly removing and then re-depositing the ions in the bottom of the etch. Because this causes the metal ions to oxidize, the bottom turns black. The voltage and amperage as well as te amount of time will determine the quality of the MARK. Too much can start to "lift" the black out.

So, ETCH first with DC to remove the metal, then MARK with AC to blacken the etch.

One technical reason to not switch back and forth is that the oxides are somewhat non-conductive and may actually make the etching slow down or stop.
Click to expand...

Okay. I will need to revisit how I do things then. I don't remember where I read, or picked up on, switching back and forth. However I will put this in my shop notes for future use.
Mea Culpa
 
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