homemade Ferric Chloride problem

Thread Starter

psoke0

Joined Mar 31, 2017
131
hello guys i just try to make ferric chloride for pcb etching. i put some iron in a bottle and add muriatic acid its dissolved all the iron and turn into green color. then i put air pump pipe into it and after couple of hours its turned into brown color. i put some copper pcb in it just to try it. its doesnt etch the copper its turning copper in a little grey color but no etching. i put some iron in it and its starts reating with the iron but not with copper at all. i tryied copper wire also it dint react with it what is the problem . i heated up the ferric chloride too its didnt do anything either :( why is that
 

Thread Starter

psoke0

Joined Mar 31, 2017
131
Did you keep adding iron until no more would dissolve?
Then bubble the air for a long time.
well i added alot of iron whool everything is dissolved and some resudue left i thought its left iron that doesnt dissolve . should i add more iron the brown color one until its cant dissolve any ?
 

jpanhalt

Joined Jan 18, 2008
10,480
Did you weigh the iron wool? As I recall, concentrated FeCl3 is about 40% by weight. It is sold by the barrel for sewage treatment. Can you weigh 100 ml or whatever of your solution and tell us what it weighs per volume?

Brown can be deceiving. Over a white surface is it brown or olive drab (brown + green)?

By far the most reproducible way is to buy ferric chloride hexahydrate. It comes as amorphous chunks with a slight acidic odor. Cupric chloride also works well. and regenerated with just air and a bit of HCl.
 

Thread Starter

psoke0

Joined Mar 31, 2017
131
Did you weigh the iron wool? As I recall, concentrated FeCl3 is about 40% by weight. It is sold by the barrel for sewage treatment. Can you weigh 100 ml or whatever of your solution and tell us what it weighs per volume?

Brown can be deceiving. Over a white surface is it brown or olive drab (brown + green)?

By far the most reproducible way is to buy ferric chloride hexahydrate. It comes as amorphous chunks with a slight acidic odor. Cupric chloride also works well. and regenerated with just air and a bit of HCl.
unfortunately i cant weight it idont have that kind of scale yet
 

Papabravo

Joined Feb 24, 2006
14,662
Doing chemistry this way might be fun, but terribly difficult to achieve reliable, repeatable results. IMHO, a complete waste of time.
 

jpanhalt

Joined Jan 18, 2008
10,480
40% ferric chloride in water weights 1.4 x an equal volume of just water. In other words, 100 ml of ferric chloride weighs the same as 140 ml water. You may not be able to assess weight to a few grams, but a given volume of ferric chloride solution will weight noticeably more than the same volume of water.

40% is not required for good etching. In fact, I add a little water to mine to make it less viscous. A little HCl excess also helps. I suspect your ferric chloride solution is probably only a few percent.
 
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Thread Starter

psoke0

Joined Mar 31, 2017
131
40% ferric chloride in water weight 1.4 x and equal volume of just water. In other words, 100 ml of ferric chloride weighs the same as 140 ml water. You may bot be able to assess weight to a few grams, but a given volume of ferric chloride solution will weight noticeable more than the same volume of water.

40% is not required for good etching. In fact, I add a little water to mine to make it less viscous. A little HCl excess also helps. I suspect your ferric chloride solution is probably only a few percent.
ohh thank youuu ishould test it now and see if its matches with water weight then i will know give or take how much percent is my ferric chloride is
 

Papabravo

Joined Feb 24, 2006
14,662
what should do then how much iron and how much ml of muriatic acid
Get the proper laboratory tools and safety equipment. Learn a little something about measurement and laboratory procedure. Taking the approach you are taking has some serious safety implications. I hope you don't lose an eye, or require a trip to the Emergency Room. You scare the crap out of me with your haphazard approach.
 

Thread Starter

psoke0

Joined Mar 31, 2017
131
Get the proper laboratory tools and safety equipment. Learn a little something about measurement and laboratory procedure. Taking the approach you are taking has some serious safety implications. I hope you don't lose an eye, or require a trip to the Emergency Room. You scare the crap out of me with your haphazard approach.
well i do have safety equipment when working on it and im oing it outside for not breath the fumes
 

Papabravo

Joined Feb 24, 2006
14,662
well i do have safety equipment when working on it and im oing it outside for not breath the fumes
You still lack the proper tools and equipment. Without those you are just pissing in the wind.
You don't seem to appreciate the fact that your fabricated boards will be crap if the materials you use contain impurities. Do you have any clue about potential impurities in your homemade Ferric Chloride? You should visit a PCB fabrication house and observe the "clean room" procedures they employ. I'm not saying you can match them, but I am saying you need a better understanding of what you are trying to do.
 
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Thread Starter

psoke0

Joined Mar 31, 2017
131
You still lack the proper tools and equipment. Without those you are just pissing in the wind.
You don't seem to appreciate the fact that your fabricated boards will be crap if the materials you use contain impurities. Do you have any clue about potential impurities in your homemade Ferric Chloride? You should visit a PCB fabrication house and observe the "clean room" procedures they employ. I'm not saying you can match them, but I am saying you need a better understanding of what you are trying to do.
i will try to be more carefull about this
 

Papabravo

Joined Feb 24, 2006
14,662
so i have low concentration muriatic acid
This is a really good point. what you REALLY need to know is how many moles of HCl you have along with how many moles of H2O to make a particular concentration of acid in solution
1 mole of HCl is about 36.4 grams. and a liter of HCl would be about 6 moles. So a liter of 100% HCl should be about 218 grams.
Every acid is different, and for example a liter of Sulfuric acid is about 18 moles for one liter

One thing you always remember in dealing with concentrated acid is to NEVER EVER under ANY CIRCUMSTANCES dilute a pure acid by adding water to it. Your injuries will be painful, extreme, and life threatening. You always add the pure acid to a suitable quantity of water which you have computed ahead of time.

This is also a good practice to follow when diluting a solution that is less than 100% acid. Just for the consistency it encourages.
 
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jpanhalt

Joined Jan 18, 2008
10,480
This is a really good point. what you REALLY need to know is how many moles of HCl you have along with how many moles of H2O to make a particular concentration of acid in solution
1 mole of HCl is about 36.4 grams. and a liter of HCl would be about 6 moles. so a liter of 100% HCl should be about 218 grams.
Every acid is different, and for example a liter of Sulfuric acid is about 18 moles for one liter

One thing you always remember in dealing with concentrated acid is to NEVER EVER under ANY CIRCUMSTANCES dilute a pure acid by adding water to it. Your injuries will be painful, extreme, and life threatening. You always add the pure acid to a suitable quantity of water which you have computed ahead of time.

This is also a good practice to follow when diluting a solution that is less than 100% acid. Just for the consistency it encourages.
You seem to forget that muriatic acid (aka "HCl") is not a gas. As a gas, which you seem to assume, the standard volume for a gas is 22.4 L per mole (there is some discussion about changing that). It is in solution. Solutions of HCl in water deviate from "ideal" solutions significantly.
 
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