Echant Concentrations.

[Drq]

So I have been looking around at information on etching solutions, and I was wondering if anyone had any idea of the actual concentration of the formulas they're using. I see all the time that one should mix one part acid "A" with three parts water. Well I'm going to guess that very few people etching pattern welded steel have access to pure acid, which means that its already mixed with water. So what is the actual end concentration ? I just bought some reagent grade nitric acid, which is 70%, but it can also be purchased in many other different percentages.


I've also seen that people say etching formulas work better when diluted.... ? So basically people are saying that a lower concentration etches faster ? Or is it just a better looking etch ? Or does it smell prettier ?

Thanks for the help, I've tried finding the numbers on my own with no avail, maybe I'm just looking in the wrong place.....now where did I put that chuck wrench again.....

Drq

[Steve Sells]

I use ferric Chloride at @ 1.5%, Hydrochloric @ 5%, Sulfuric @ 5% I have not measured Ph. I read labels to find the concentration, and add to water accordingly.

in English:
Radio Shack PCB etchant 1:3 water.
Hydrochloric I get at 30% from pool supply (muratic) , and Sulfuric from auto zone, I add to water bringing down to 5% mainly for topographical then a finish etch in Ferric chloride for color.
Vinegar I use alone, for high layer blades (over 400 layers) white vinegar to 1 or 1.5 part water.
I have no Nitric.

Warming speeds up etching, and many seem to be in a hurry and prefer this. I like slow etches, as they appear more even to me. My Swords I use Vinegar 6 to 10 hours, very slow to etch but detail is great.

[ThomasPowers]

What we are trying to do is DIFFERENTIAL etching. Strong acid solutions tend to etch *everything*; weak is more likely to etch some alloys better than others bringing up the pattern we are trying to show. Weak acid solutions do not etch *faster*; they etch *better*! Make more sense to you?

[Rich Hale]

I use ferric chloride only. I mix it with water..one part etchant four water. I do not care wot the concentration is. I am olld and have decided that I no longer care to delve deeper than wot I know will work. The first few blades I etched I used it straight from the Radio Shack bottle. I etched and i etched and etc with very little results. But slowly it dawned on me that each time I etched the part got a black crud on all lsurfaces and when that happened the etching slowed waaaaay down. So I diluted with water, That seemd like a wrong turn as i thought that how could wot seemed to me to slow down the affect of the acid be a good thing? So Now I do this: I etch with the dilution and about every fifteen to twenty minutes I remove the piece and wipe all surfaces with lots of water and a new piece of 1500 grit wet or dry. That removes the black goop and allows the solution to work, I think a bit faster. When I get the etch the way I want it to be I neutralize all traces of the etchant and oil the piece. I do this all in a warm environment which is why I live in AZ. I do not use other acids and if you do you should consider scanning the MSDS sheets to see if they produce hazards from vapor or from skin contact.

[Randy Jr. HHH Knives]

I agree with Rich, i use pcb etchant from radio shack. i dilute about 3:1. and have also found lightly sanding every 15 min or so gives you the best etch. then oil. Its what works for me anyway, hope it helps

[Steve Sells]

I should add I wipe off the black goo every 15 minutes or so as well. Also I do warm the soda water I use to neutralize. and defiantly OIL it soon as the rinse is finished. very clean metals rust fast.

MSDS is mandatory is you have any type of business, and I am use to working with these chemicals from my day job. Always add acid to water. Never the reverse.

[Drq]

Thanks for the help, I understand now that faster doesn't equal better with what we are trying to accomplish. Any idea on buying bulk quantities of PCB etchant ? I'm hoping to etch a 24" blade and it seems kinda silly to purchase it in 6 oz bottles.

[Drq]

Hey Steve, why go with the two different etchants ? You mention Ferric Chloride for colouring, could you explain that a bit ?

[Steve Sells]

Actually I have 3 I use for different things: Muratic (Hydrochloric) Acid, Ferric Chloride, and simple vinegar.

Why do we make blades from different steels? they all perform in different ways, not as much color from the Muratic, but a lot of surface textures. Try and see :)

[PeterM]

Steve, et al: In your first post in this thread you mentioned that you've not measured the Ph of Ferric Chloride. I wonder, if you did measure the final etching concentration, what Ph would it be?

I ask because of an "enlightening" experience I had recently when mixing up my first-ever batch intended for blade etching. The short of the story being that the glass mixing jar cracked at its base spilling most of the contents onto my gravel driveway. The result of my hapless bumbling is about a 1/2 gallon of rescued liquid of unknown concentration.

In lew of litmus paper and an accurate Ph measure, are there any tricks/tips on how to "zero in" my mixture to a proper concentration.

Here's a "morning after" photo of my evening escapades.