Homebrew PCBs

>
>Thanks in advance,
>Bob

>
> On Sun, 28 Oct 2012 05:21:57 -0000, you wrote:
> 
> >I have been using H2O2 from the pharmacy / Muriatic Acid combo, 2:1 - works well and is easy to get, but it doesn't work after the initial use.  It seems every etch, I need to make a new batch.  The etchant turns into a bright lime green color on the first etch and it does what I need to pretty quick and it seems like there is decent activity - bubbles which only happens on the first time use, after that maybe bubbles when I first put in the pcb/Cu but they go away very quickly.
> >
> >After use, I will put the solution in a clear, sealed glass container and even if I use it the next day, after I start, 45min later my etch is still not done, so I dispose of it and make a new batch at which time I am done in 15mins.
> >
> >What am I doing wrong or where is the mixture out of balance?  Again, I just did an etch this evening and had to make a new batch, which is now a bright lime green color.
> 
> The etchant uses the oxygen from the peroxide to enable the etching.
> To continue to etch with that solution, you need to bubble air through
> it.  It will also help to heat the solution to 100 degrees F or so.
> 
> The solution will gradually turn a darker green.  If it turns olive
> (IIRC), then the chemistry is out of balance.  The peroxide provides
> oxygen only for the first day or so, at which point the etchant turns
> into a CuCl etchant, which works very well, is a trifle slower, but
> never wears out.  I think that there's a good review of this chemistry
> in the group archives, which explanation is better than mine.
> 
> You'll find that if you add some relatively concentrated peroxide to
> the etchant, it will start to work the way you expect, but the word is
> concentrated.  Not really needed.
> 
> Some people take the peroxide etchant mix and deliberately add copper
> to it, producing the CuCl etchant to start with.
> 
> You will eventually have to add either Muriatic acid to the mix to
> replace the chloride ion, again, IIRC.
> 
> Harvey
> 
> >
> >Thanks in advance,
> >Bob
>

>
> On 28/10/12 16:38, dubob4432 wrote:
> > Thanks.
> >
> > When you say 'bubble air through it' you mean like w/ a fish tank air pump w/
> > those 1 way valves?  Do I know how much air I need based off the color and if
> > so, what color am I looking for?  In the past I had some weak acid and it
> > turned teal blue but this stuff is staying bright lime green.
> >
> > Also, yes, I did heat it up.  I was using a small 'tupperware' dish in a
> > larger one that was filled w/ water ~120-140F.
> >
> > When you say a bit slower, I assume you mean than the first batch and not my
> > slow 45min marathon etch?
> 
> Using my FeCl bubble etcher which has degenerated to a copper-chloride etcher, 
> doing a double-sided 1oz copper pcb is well done by 12 minutes, without heating.
> 
> Add a bit of HCl acid every few months. The FeCl/water ratio started at 1:1 a 
> few years ago. Keep the tank covered when not in use.
>

>
> On 28/10/12 17:06, dubob4432 wrote:
> > Will do, anybody know if the storage vessel needs to be dark?  Does sunlight dilute it?
> 
> Sunlight doesn't affect FeCl or CuCl. Don't let it stay warm unless it's covered 
> well to prevent evaporation. Peroxide etchant stuff may go off quicker when in 
> sunlight and warmed.
>

>
>Bob
>
>--- In Homebrew_PCBs@yahoogroups.com, Harvey White <madyn@...> wrote:
>>
>> On Sun, 28 Oct 2012 05:21:57 -0000, you wrote:
>> 
>> >I have been using H2O2 from the pharmacy / Muriatic Acid combo, 2:1 - works well and is easy to get, but it doesn't work after the initial use.  It seems every etch, I need to make a new batch.  The etchant turns into a bright lime green color on the first etch and it does what I need to pretty quick and it seems like there is decent activity - bubbles which only happens on the first time use, after that maybe bubbles when I first put in the pcb/Cu but they go away very quickly.
>> >
>> >After use, I will put the solution in a clear, sealed glass container and even if I use it the next day, after I start, 45min later my etch is still not done, so I dispose of it and make a new batch at which time I am done in 15mins.
>> >
>> >What am I doing wrong or where is the mixture out of balance?  Again, I just did an etch this evening and had to make a new batch, which is now a bright lime green color.
>> 
>> The etchant uses the oxygen from the peroxide to enable the etching.
>> To continue to etch with that solution, you need to bubble air through
>> it.  It will also help to heat the solution to 100 degrees F or so.
>> 
>> The solution will gradually turn a darker green.  If it turns olive
>> (IIRC), then the chemistry is out of balance.  The peroxide provides
>> oxygen only for the first day or so, at which point the etchant turns
>> into a CuCl etchant, which works very well, is a trifle slower, but
>> never wears out.  I think that there's a good review of this chemistry
>> in the group archives, which explanation is better than mine.
>> 
>> You'll find that if you add some relatively concentrated peroxide to
>> the etchant, it will start to work the way you expect, but the word is
>> concentrated.  Not really needed.
>> 
>> Some people take the peroxide etchant mix and deliberately add copper
>> to it, producing the CuCl etchant to start with.
>> 
>> You will eventually have to add either Muriatic acid to the mix to
>> replace the chloride ion, again, IIRC.
>> 
>> Harvey
>> 
>> >
>> >Thanks in advance,
>> >Bob
>>
>

>
> I have been using H2O2 from the pharmacy / Muriatic Acid combo, 2:1 - works well and is easy to get, but it doesn't work after the initial use.  It seems every etch, I need to make a new batch.  The etchant turns into a bright lime green color on the first etch and it does what I need to pretty quick and it seems like there is decent activity - bubbles which only happens on the first time use, after that maybe bubbles when I first put in the pcb/Cu but they go away very quickly.
> 
> After use, I will put the solution in a clear, sealed glass container and even if I use it the next day, after I start, 45min later my etch is still not done, so I dispose of it and make a new batch at which time I am done in 15mins.
> 
> What am I doing wrong or where is the mixture out of balance?  Again, I just did an etch this evening and had to make a new batch, which is now a bright lime green color.
> 
> Thanks in advance,
> Bob
>

>
> You can purify 3% (drugstore grade of H2O2) by placing the H2O2 solution in a dark plastic bottle. No grease or other organic except the plastic and definitely not in a stainless steel or other steel vessel and FREEZE IT IN A DEEP FREEZER. When the solution has formed ice, remove the ice and the remaining liquid is concentrated H2O2. And you can use the concentrated H2O2 into your Acid bath without diluting the concentration of HCl (well not as much as if you had used 3% H2O2).
> 
> Word of WARNING!! concentrated H2O2 can be very unstable so do NOT make a big batch! Make only what you need for the acid bath. Do not allow it to come in contact with oil, flesh, stainless steel. Steel act as a catalyst to decompose H2O2 in highly exothermic (heat producing) decomposition of H2O2 into water and oxygen. The reaction can runaway and cause the container to explode from too much pressure build up from oxygen generation. H2O2 does not explode chemically. 
> 
> Far as storage of acid bath with H2O2. keep it away from sunlight, halogen light or any light with blue and UV in it. Light will promote decomposition of H2O2.
> 
> ---- on slightly different subject using vinegar ----
> 
> Vinegar is acetic acid. Grocery store vinegar is only about 4% acetic acid. If you want to concentrate and use it for etching copper I think you can do this... To concentrate vinegar you can also freeze the vinegar and remove the ice. It's relatively easy to get 40% concentration of acetic acid if I remember correctly.
> 
> Be safe!
> Ms. Smilingcat
> 
> Thank you for your note Mitch
> 
> --- In Homebrew_PCBs@yahoogroups.com, "dubob4432" <dubob4432@> wrote:
> >
> > I have been using H2O2 from the pharmacy / Muriatic Acid combo, 2:1 - works well and is easy to get, but it doesn't work after the initial use.  It seems every etch, I need to make a new batch.  The etchant turns into a bright lime green color on the first etch and it does what I need to pretty quick and it seems like there is decent activity - bubbles which only happens on the first time use, after that maybe bubbles when I first put in the pcb/Cu but they go away very quickly.
> > 
> > After use, I will put the solution in a clear, sealed glass container and even if I use it the next day, after I start, 45min later my etch is still not done, so I dispose of it and make a new batch at which time I am done in 15mins.
> > 
> > What am I doing wrong or where is the mixture out of balance?  Again, I just did an etch this evening and had to make a new batch, which is now a bright lime green color.
> > 
> > Thanks in advance,
> > Bob
> >
>

 From: dubob4432 <dubob4432@...>
To: Homebrew_PCBs@yahoogroups.com 
Sent: Tuesday, November 13, 2012 1:25 PM
Subject: [Homebrew_PCBs] Re: Kepping Your Etchant Good?  Multiple Use?  Muriatic Acid / H2O2
 

  
Thanks for the info, on the hunt for a dark plastic bottle.

Bob

--- In Homebrew_PCBs@yahoogroups.com, "smilingcat90254" <smilingcat@...> wrote:
>
> You can purify 3% (drugstore grade of H2O2) by placing the H2O2 solution in a dark plastic bottle. No grease or other organic except the plastic and definitely not in a stainless steel or other steel vessel and FREEZE IT IN A DEEP FREEZER. When the solution has formed ice, remove the ice and the remaining liquid is concentrated H2O2. And you can use the concentrated H2O2 into your Acid bath without diluting the concentration of HCl (well not as much as if you had used 3% H2O2).
> 
> Word of WARNING!! concentrated H2O2 can be very unstable so do NOT make a big batch! Make only what you need for the acid bath. Do not allow it to come in contact with oil, flesh, stainless steel. Steel act as a catalyst to decompose H2O2 in highly exothermic (heat producing) decomposition of H2O2 into water and oxygen. The reaction can runaway and cause the container to explode from too much pressure build up from oxygen generation. H2O2 does not explode chemically. 
> 
> Far as storage of acid bath with H2O2. keep it away from sunlight, halogen light or any light with blue and UV in it. Light will promote decomposition of H2O2.
> 
> ---- on slightly different subject using vinegar ----
> 
> Vinegar is acetic acid. Grocery store vinegar is only about 4% acetic acid. If you want to concentrate and use it for etching copper I think you can do this... To concentrate vinegar you can also freeze the vinegar and remove the ice. It's relatively easy to get 40% concentration of acetic acid if I remember correctly.
> 
> Be safe!
> Ms. Smilingcat
> 
> Thank you for your note Mitch
> 
> --- In Homebrew_PCBs@yahoogroups.com, "dubob4432" <dubob4432@> wrote:
> >
> > I have been using H2O2 from the pharmacy / Muriatic Acid combo, 2:1 - works well and is easy to get, but it doesn't work after the initial use.  It seems every etch, I need to make a new batch.  The etchant turns into a bright lime green color on the first etch and it does what I need to pretty quick and it seems like there is decent activity - bubbles which only happens on the first time use, after that maybe bubbles when I first put in the pcb/Cu but they go away very quickly.
> > 
> > After use, I will put the solution in a clear, sealed glass container and even if I use it the next day, after I start, 45min later my etch is still not done, so I dispose of it and make a new batch at which time I am done in 15mins.
> > 
> > What am I doing wrong or where is the mixture out of balance?  Again, I just did an etch this evening and had to make a new batch, which is now a bright lime green color.
> > 
> > Thanks in advance,
> > Bob
> >
>


 

[Non-text portions of this message have been removed]

>
> You can purify 3% (drugstore grade of H2O2) by placing the H2O2 solution in a dark plastic bottle. No grease or other organic except the plastic and definitely not in a stainless steel or other steel vessel and FREEZE IT IN A DEEP FREEZER. When the solution has formed ice, remove the ice and the remaining liquid is concentrated H2O2. And you can use the concentrated H2O2 into your Acid bath without diluting the concentration of HCl (well not as much as if you had used 3% H2O2).
> 
> Word of WARNING!! concentrated H2O2 can be very unstable so do NOT make a big batch! Make only what you need for the acid bath. Do not allow it to come in contact with oil, flesh, stainless steel. Steel act as a catalyst to decompose H2O2 in highly exothermic (heat producing) decomposition of H2O2 into water and oxygen. The reaction can runaway and cause the container to explode from too much pressure build up from oxygen generation. H2O2 does not explode chemically. 
> 
> Far as storage of acid bath with H2O2. keep it away from sunlight, halogen light or any light with blue and UV in it. Light will promote decomposition of H2O2.
> 
> ---- on slightly different subject using vinegar ----
> 
> Vinegar is acetic acid. Grocery store vinegar is only about 4% acetic acid. If you want to concentrate and use it for etching copper I think you can do this... To concentrate vinegar you can also freeze the vinegar and remove the ice. It's relatively easy to get 40% concentration of acetic acid if I remember correctly.
> 
> Be safe!
> Ms. Smilingcat
> 
> Thank you for your note Mitch
> 
> --- In Homebrew_PCBs@yahoogroups.com, "dubob4432" <dubob4432@> wrote:
> >
> > I have been using H2O2 from the pharmacy / Muriatic Acid combo, 2:1 - works well and is easy to get, but it doesn't work after the initial use.  It seems every etch, I need to make a new batch.  The etchant turns into a bright lime green color on the first etch and it does what I need to pretty quick and it seems like there is decent activity - bubbles which only happens on the first time use, after that maybe bubbles when I first put in the pcb/Cu but they go away very quickly.
> > 
> > After use, I will put the solution in a clear, sealed glass container and even if I use it the next day, after I start, 45min later my etch is still not done, so I dispose of it and make a new batch at which time I am done in 15mins.
> > 
> > What am I doing wrong or where is the mixture out of balance?  Again, I just did an etch this evening and had to make a new batch, which is now a bright lime green color.
> > 
> > Thanks in advance,
> > Bob
> >
>

>
> On 11/17/2012 5:10 PM, dubob4432 wrote:
> >
> > since hair dye uses hydrogen peroxide in 10%, 20% and 30% strengths, 
> > would this be a better way to go?
> >
> > reason i ask is because the only freezer i have is a regular 
> > freezer/fridge unit and not sure if it would get cool enough?
> >
> > bob
> >
> Beauty shop H2O2 is 10  - 20  - 30 VOLUME, not %.  It works out to 6  - 
> 9  - 12 %
> 
> Norm
> 
> 
> [Non-text portions of this message have been removed]
>

  ----- Original Message ----- 
  From: dubob4432 
  To: Homebrew_PCBs@yahoogroups.com 
  Sent: Saturday, November 17, 2012 8:10 PM
  Subject: [Homebrew_PCBs] Re: Kepping Your Etchant Good? Multiple Use? Muriatic Acid / H2O2


    
  since hair dye uses hydrogen peroxide in 10%, 20% and 30% strengths, would this be a better way to go?

  reason i ask is because the only freezer i have is a regular freezer/fridge unit and not sure if it would get cool enough?

  bob

  --- In Homebrew_PCBs@yahoogroups.com, "smilingcat90254" <smilingcat@...> wrote:
  >
  > You can purify 3% (drugstore grade of H2O2) by placing the H2O2 solution in a dark plastic bottle. No grease or other organic except the plastic and definitely not in a stainless steel or other steel vessel and FREEZE IT IN A DEEP FREEZER. When the solution has formed ice, remove the ice and the remaining liquid is concentrated H2O2. And you can use the concentrated H2O2 into your Acid bath without diluting the concentration of HCl (well not as much as if you had used 3% H2O2).
  > 
  > Word of WARNING!! concentrated H2O2 can be very unstable so do NOT make a big batch! Make only what you need for the acid bath. Do not allow it to come in contact with oil, flesh, stainless steel. Steel act as a catalyst to decompose H2O2 in highly exothermic (heat producing) decomposition of H2O2 into water and oxygen. The reaction can runaway and cause the container to explode from too much pressure build up from oxygen generation. H2O2 does not explode chemically. 
  > 
  > Far as storage of acid bath with H2O2. keep it away from sunlight, halogen light or any light with blue and UV in it. Light will promote decomposition of H2O2.
  > 
  > ---- on slightly different subject using vinegar ----
  > 
  > Vinegar is acetic acid. Grocery store vinegar is only about 4% acetic acid. If you want to concentrate and use it for etching copper I think you can do this... To concentrate vinegar you can also freeze the vinegar and remove the ice. It's relatively easy to get 40% concentration of acetic acid if I remember correctly.
  > 
  > Be safe!
  > Ms. Smilingcat
  > 
  > Thank you for your note Mitch
  > 
  > --- In Homebrew_PCBs@yahoogroups.com, "dubob4432" <dubob4432@> wrote:
  > >
  > > I have been using H2O2 from the pharmacy / Muriatic Acid combo, 2:1 - works well and is easy to get, but it doesn't work after the initial use. It seems every etch, I need to make a new batch. The etchant turns into a bright lime green color on the first etch and it does what I need to pretty quick and it seems like there is decent activity - bubbles which only happens on the first time use, after that maybe bubbles when I first put in the pcb/Cu but they go away very quickly.
  > > 
  > > After use, I will put the solution in a clear, sealed glass container and even if I use it the next day, after I start, 45min later my etch is still not done, so I dispose of it and make a new batch at which time I am done in 15mins.
  > > 
  > > What am I doing wrong or where is the mixture out of balance? Again, I just did an etch this evening and had to make a new batch, which is now a bright lime green color.
  > > 
  > > Thanks in advance,
  > > Bob
  > >
  >



  

[Non-text portions of this message have been removed]

  ----- Original Message ----- 
  From: Dave Sage 
  To: Homebrew_PCBs@yahoogroups.com 
  Sent: Sunday, November 18, 2012 9:58 AM
  Subject: [Homebrew_PCBs] Re: Kepping Your Etchant Good? Multiple Use? Muriatic Acid / H2O2


    
  FYI

  If you are using the Muriatic Acid /H2O2 formulation correctly you never
  need to add more H2O2. Somewhere along the way the original intent of this
  formulation has been lost here. You all should go back and read the original
  post on making Cupric Chloride. You start with acid and H2O2 and saturate it
  with copper. From there you just have to bubble air into it for an extended
  period of time to turn it into Cupric Chloride and it's ready to go. You are
  defeating the purpose by using the acid H2O2 for one time use. Do your
  etching and then return it to a container for more bubbling in the off time
  to convert it to Cupric Chloride again. Lasts forever. In fact you actually
  gain slightly more volume of etchant after each use. Cupric Chloride is used
  in industry now since it is re-usable "more green - no pun intended - since
  Cupric Chloride is green"

  Sage

  [Non-text portions of this message have been removed]



  

[Non-text portions of this message have been removed]

>
> Not quite that simple.  You do have to add HCl occasionally to provide chloride ion.
> 
> When I switched from ferric chloride, I started with copper (II) chloride and have been using that bath for several years.  I use air for regeneration; although, peroxide will work too, but common 3% will dilute the bath.  Ozone will also work and is quicker than air, but requires a generator.  Common household air fresheners don't produce enough ozone to be very helpful, though.  
> 
> John
> 
>   ----- Original Message ----- 
>   From: Dave Sage 
>   To: Homebrew_PCBs@yahoogroups.com 
>   Sent: Sunday, November 18, 2012 9:58 AM
>   Subject: [Homebrew_PCBs] Re: Kepping Your Etchant Good? Multiple Use? Muriatic Acid / H2O2
> 
> 
>     
>   FYI
> 
>   If you are using the Muriatic Acid /H2O2 formulation correctly you never
>   need to add more H2O2. Somewhere along the way the original intent of this
>   formulation has been lost here. You all should go back and read the original
>   post on making Cupric Chloride. You start with acid and H2O2 and saturate it
>   with copper. From there you just have to bubble air into it for an extended
>   period of time to turn it into Cupric Chloride and it's ready to go. You are
>   defeating the purpose by using the acid H2O2 for one time use. Do your
>   etching and then return it to a container for more bubbling in the off time
>   to convert it to Cupric Chloride again. Lasts forever. In fact you actually
>   gain slightly more volume of etchant after each use. Cupric Chloride is used
>   in industry now since it is re-usable "more green - no pun intended - since
>   Cupric Chloride is green"
> 
>   Sage
> 
>   [Non-text portions of this message have been removed]
> 
> 
> 
>   
> 
> [Non-text portions of this message have been removed]
>

>
> You can purify 3% (drugstore grade of H2O2) by placing the H2O2 solution in a dark plastic bottle. No grease or other organic except the plastic and definitely not in a stainless steel or other steel vessel and FREEZE IT IN A DEEP FREEZER. When the solution has formed ice, remove the ice and the remaining liquid is concentrated H2O2. And you can use the concentrated H2O2 into your Acid bath without diluting the concentration of HCl (well not as much as if you had used 3% H2O2).
> 
> Word of WARNING!! concentrated H2O2 can be very unstable so do NOT make a big batch! Make only what you need for the acid bath. Do not allow it to come in contact with oil, flesh, stainless steel. Steel act as a catalyst to decompose H2O2 in highly exothermic (heat producing) decomposition of H2O2 into water and oxygen. The reaction can runaway and cause the container to explode from too much pressure build up from oxygen generation. H2O2 does not explode chemically. 
> 
> Far as storage of acid bath with H2O2. keep it away from sunlight, halogen light or any light with blue and UV in it. Light will promote decomposition of H2O2.
> 
> ---- on slightly different subject using vinegar ----
> 
> Vinegar is acetic acid. Grocery store vinegar is only about 4% acetic acid. If you want to concentrate and use it for etching copper I think you can do this... To concentrate vinegar you can also freeze the vinegar and remove the ice. It's relatively easy to get 40% concentration of acetic acid if I remember correctly.
> 
> Be safe!
> Ms. Smilingcat
> 
> Thank you for your note Mitch
>

>
>Steve Greenfield AE7HD
>
>--- In Homebrew_PCBs@yahoogroups.com, "smilingcat90254" <smilingcat@...> wrote:
>>
>> You can purify 3% (drugstore grade of H2O2) by placing the H2O2 solution in a dark plastic bottle. No grease or other organic except the plastic and definitely not in a stainless steel or other steel vessel and FREEZE IT IN A DEEP FREEZER. When the solution has formed ice, remove the ice and the remaining liquid is concentrated H2O2. And you can use the concentrated H2O2 into your Acid bath without diluting the concentration of HCl (well not as much as if you had used 3% H2O2).
>> 
>> Word of WARNING!! concentrated H2O2 can be very unstable so do NOT make a big batch! Make only what you need for the acid bath. Do not allow it to come in contact with oil, flesh, stainless steel. Steel act as a catalyst to decompose H2O2 in highly exothermic (heat producing) decomposition of H2O2 into water and oxygen. The reaction can runaway and cause the container to explode from too much pressure build up from oxygen generation. H2O2 does not explode chemically. 
>> 
>> Far as storage of acid bath with H2O2. keep it away from sunlight, halogen light or any light with blue and UV in it. Light will promote decomposition of H2O2.
>> 
>> ---- on slightly different subject using vinegar ----
>> 
>> Vinegar is acetic acid. Grocery store vinegar is only about 4% acetic acid. If you want to concentrate and use it for etching copper I think you can do this... To concentrate vinegar you can also freeze the vinegar and remove the ice. It's relatively easy to get 40% concentration of acetic acid if I remember correctly.
>> 
>> Be safe!
>> Ms. Smilingcat
>> 
>> Thank you for your note Mitch
>>

>
> On Sun, 18 Nov 2012 16:37:24 -0000, you wrote:
> 
> >Yes, keep in mind that the rocket backpack used in the 007 movie uses nothing but concentrated hydrogen peroxide. It hits a mesh of metal and instantly turns to H20, O2, and an incredible amount of heat.
> 
> The metal is platinum, IIRC.
> 
> Good reason to avoid using platinum tools when you make PC
> boards......
> 
> Harvey
> 
> >
> >Steve Greenfield AE7HD
> >
> >--- In Homebrew_PCBs@yahoogroups.com, "smilingcat90254" <smilingcat@> wrote:
> >>
> >> You can purify 3% (drugstore grade of H2O2) by placing the H2O2 solution in a dark plastic bottle. No grease or other organic except the plastic and definitely not in a stainless steel or other steel vessel and FREEZE IT IN A DEEP FREEZER. When the solution has formed ice, remove the ice and the remaining liquid is concentrated H2O2. And you can use the concentrated H2O2 into your Acid bath without diluting the concentration of HCl (well not as much as if you had used 3% H2O2).
> >> 
> >> Word of WARNING!! concentrated H2O2 can be very unstable so do NOT make a big batch! Make only what you need for the acid bath. Do not allow it to come in contact with oil, flesh, stainless steel. Steel act as a catalyst to decompose H2O2 in highly exothermic (heat producing) decomposition of H2O2 into water and oxygen. The reaction can runaway and cause the container to explode from too much pressure build up from oxygen generation. H2O2 does not explode chemically. 
> >> 
> >> Far as storage of acid bath with H2O2. keep it away from sunlight, halogen light or any light with blue and UV in it. Light will promote decomposition of H2O2.
> >> 
> >> ---- on slightly different subject using vinegar ----
> >> 
> >> Vinegar is acetic acid. Grocery store vinegar is only about 4% acetic acid. If you want to concentrate and use it for etching copper I think you can do this... To concentrate vinegar you can also freeze the vinegar and remove the ice. It's relatively easy to get 40% concentration of acetic acid if I remember correctly.
> >> 
> >> Be safe!
> >> Ms. Smilingcat
> >> 
> >> Thank you for your note Mitch
> >>
>