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Home made etchant

Home made etchant

2003-04-27 by frajopea

Hello,

I've been reading for a few weeks now, this is my first post.

There was a post about regenerating FeCl using HCl, I had a bunch of 
used up and very rusty etchant lying around so I did it. I poured HCl 
in the used etchant and the result was a very nice clear green/bluish 
solution that etched boards again. I was impressed.

Then there was the CuCl2 thread, where you just use copper, HCl and 
H2O...

With all this in mind, I kept using my regenerated etchant and 
pouring some HCl every now and then when it started to look brown. 
The thing is, now the etchant is brown, no matter how much HCl I put 
in it, I can't get it back to the clear transparent green I first had.

The other day, I was cleaning a board using water and: the clear 
green solution!... I made the experiment of adding water to a sample 
of the etchant and it did change color and turned clear green. The 
only problem is: it didn't etch, at least not fast enough for me to 
notice.

Now, I don't know enough about chemistry to figure this out, but is 
it possible that if I add copper and do the bubbling, that it'll turn 
clear green again? I mean, I think there's too much HCl and not 
enough of the other stuff!

Thanks,
Fp
www.tonepad.com

Re: [Homebrew_PCBs] Home made etchant

2003-04-28 by Adam Seychell

I've seen what you have just described. What you are doing when 
adding water to a dark solution of CuCl2 and some CuCl is the 
CuCl precipitates out as what solid on dilution, thus leaving 
only green CuCl2. The CuCl is only soluble (which makes the 
solution dark brown) when the chloride ion concentration is high.
Diluting will of course also reduce the concentration of CuCl2 
and slow down etching rate.

If you bubble enough air through the solution it *WILL* 
eventually go deep green. Put a drop on a white piece of plastic 
and come back in a few hours, if turns clear green then it means 
the solution is not complete regenerated. Fine bubbles are many 
times more efficient at regeneration than large bubbles. Aquarium 
airstones are ideal. It can take an hour or more of vigorous 
bubbling.

Adam.

frajopea wrote:
Show quoted textHide quoted text
> Hello,
> 
> I've been reading for a few weeks now, this is my first post.
> 
> There was a post about regenerating FeCl using HCl, I had a bunch of 
> used up and very rusty etchant lying around so I did it. I poured HCl 
> in the used etchant and the result was a very nice clear green/bluish 
> solution that etched boards again. I was impressed.
> 
> Then there was the CuCl2 thread, where you just use copper, HCl and 
> H2O...
> 
> With all this in mind, I kept using my regenerated etchant and 
> pouring some HCl every now and then when it started to look brown. 
> The thing is, now the etchant is brown, no matter how much HCl I put 
> in it, I can't get it back to the clear transparent green I first had.
> 
> The other day, I was cleaning a board using water and: the clear 
> green solution!... I made the experiment of adding water to a sample 
> of the etchant and it did change color and turned clear green. The 
> only problem is: it didn't etch, at least not fast enough for me to 
> notice.
> 
> Now, I don't know enough about chemistry to figure this out, but is 
> it possible that if I add copper and do the bubbling, that it'll turn 
> clear green again? I mean, I think there's too much HCl and not 
> enough of the other stuff!
> 
> Thanks,
> Fp
> www.tonepad.com
> 
> 
> 
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
> 
>  
> 
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
> 
>

Re: [Homebrew_PCBs] Home made etchant

2003-04-28 by Francisco Peña

You say that the solution is brown because CuCl is present diluted in the etchant, and this can only happen when the chloride ion concentration is high, right?

And the way to get the etchant *right* is to bubble it a lot. Meaning I don't have to add more copper or water? (the etchant works as it is right now, btw)

About the look of the regenerated etchant: You mention deep green, I can see some green going on, at the sides of the tank where etchant has splashed, but the rest of the etchant is dark brown. Is it supposed to be clear in the end or not? If I pick up a drop of it in a piece of paper tissue it stains it green.

Thanks
Fp
Show quoted textHide quoted text
  ----- Original Message ----- 
  From: Adam Seychell 
  To: Homebrew_PCBs@yahoogroups.com 
  Sent: Sunday, April 27, 2003 8:06 PM
  Subject: Re: [Homebrew_PCBs] Home made etchant


  I've seen what you have just described. What you are doing when 
  adding water to a dark solution of CuCl2 and some CuCl is the 
  CuCl precipitates out as what solid on dilution, thus leaving 
  only green CuCl2. The CuCl is only soluble (which makes the 
  solution dark brown) when the chloride ion concentration is high.
  Diluting will of course also reduce the concentration of CuCl2 
  and slow down etching rate.

  If you bubble enough air through the solution it *WILL* 
  eventually go deep green. Put a drop on a white piece of plastic 
  and come back in a few hours, if turns clear green then it means 
  the solution is not complete regenerated. Fine bubbles are many 
  times more efficient at regeneration than large bubbles. Aquarium 
  airstones are ideal. It can take an hour or more of vigorous 
  bubbling.

  Adam.

  frajopea wrote:
  > Hello,
  > 
  > I've been reading for a few weeks now, this is my first post.
  > 
  > There was a post about regenerating FeCl using HCl, I had a bunch of 
  > used up and very rusty etchant lying around so I did it. I poured HCl 
  > in the used etchant and the result was a very nice clear green/bluish 
  > solution that etched boards again. I was impressed.
  > 
  > Then there was the CuCl2 thread, where you just use copper, HCl and 
  > H2O...
  > 
  > With all this in mind, I kept using my regenerated etchant and 
  > pouring some HCl every now and then when it started to look brown. 
  > The thing is, now the etchant is brown, no matter how much HCl I put 
  > in it, I can't get it back to the clear transparent green I first had.
  > 
  > The other day, I was cleaning a board using water and: the clear 
  > green solution!... I made the experiment of adding water to a sample 
  > of the etchant and it did change color and turned clear green. The 
  > only problem is: it didn't etch, at least not fast enough for me to 
  > notice.
  > 
  > Now, I don't know enough about chemistry to figure this out, but is 
  > it possible that if I add copper and do the bubbling, that it'll turn 
  > clear green again? I mean, I think there's too much HCl and not 
  > enough of the other stuff!
  > 
  > Thanks,
  > Fp
  > www.tonepad.com
  > 
  > 
  > 
  > Be sure to visit the group home and check for new Bookmarks and files:
  > http://groups.yahoo.com/group/Homebrew_PCBs
  > 
  > To unsubscribe from this group, send an email to:
  > Homebrew_PCBs-unsubscribe@yahoogroups.com
  > 
  >  
  > 
  > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
  > 
  > 



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

Re: [Homebrew_PCBs] Home made etchant

2003-04-28 by Adam Seychell

CuCl is copper(I) chloride, it is almost insoluble in water. When 
  chloride ion concentrations is sufficient (e.g. from HCl or 
CuCl2 or NaCl ect.) the solubility increases because copper(I) 
complexes with chloride ions. This complexed form of copper(I) 
chloride is dark brown. It doesn't take much concentration of 
copper(I) chloride complex to make it appear opaque.

CuCl2 is copper(II) chloride and is very soluble in water. At low 
concentration the color is pale blue, at higher concentration it 
goes clear green, and gets darker green as concentration 
increases. At typical concentrations used for etching the 
copper(II) chloride is a very dark green , that you cannot see 
through more than 1 inch when looking through a bright light. If 
the splashes on the side of the container look clear green then 
its pretty much all copper(II) chloride and very little copper(I) 
chloride. You can be sure that regeneration is completed.


Francisco Pe\ufffda wrote:
Show quoted textHide quoted text
> You say that the solution is brown because CuCl is present diluted in the etchant, and this can only happen when the chloride ion concentration is high, right?
> 
> And the way to get the etchant *right* is to bubble it a lot. Meaning I don't have to add more copper or water? (the etchant works as it is right now, btw)
> 
> About the look of the regenerated etchant: You mention deep green, I can see some green going on, at the sides of the tank where etchant has splashed, but the rest of the etchant is dark brown. Is it supposed to be clear in the end or not? If I pick up a drop of it in a piece of paper tissue it stains it green.
> 
> Thanks
> Fp
> 
> 
>   ----- Original Message ----- 
>   From: Adam Seychell 
>   To: Homebrew_PCBs@yahoogroups.com 
>   Sent: Sunday, April 27, 2003 8:06 PM
>   Subject: Re: [Homebrew_PCBs] Home made etchant
> 
> 
>   I've seen what you have just described. What you are doing when 
>   adding water to a dark solution of CuCl2 and some CuCl is the 
>   CuCl precipitates out as what solid on dilution, thus leaving 
>   only green CuCl2. The CuCl is only soluble (which makes the 
>   solution dark brown) when the chloride ion concentration is high.
>   Diluting will of course also reduce the concentration of CuCl2 
>   and slow down etching rate.
> 
>   If you bubble enough air through the solution it *WILL* 
>   eventually go deep green. Put a drop on a white piece of plastic 
>   and come back in a few hours, if turns clear green then it means 
>   the solution is not complete regenerated. Fine bubbles are many 
>   times more efficient at regeneration than large bubbles. Aquarium 
>   airstones are ideal. It can take an hour or more of vigorous 
>   bubbling.
> 
>   Adam.
> 
>   frajopea wrote:
>   > Hello,
>   > 
>   > I've been reading for a few weeks now, this is my first post.
>   > 
>   > There was a post about regenerating FeCl using HCl, I had a bunch of 
>   > used up and very rusty etchant lying around so I did it. I poured HCl 
>   > in the used etchant and the result was a very nice clear green/bluish 
>   > solution that etched boards again. I was impressed.
>   > 
>   > Then there was the CuCl2 thread, where you just use copper, HCl and 
>   > H2O...
>   > 
>   > With all this in mind, I kept using my regenerated etchant and 
>   > pouring some HCl every now and then when it started to look brown. 
>   > The thing is, now the etchant is brown, no matter how much HCl I put 
>   > in it, I can't get it back to the clear transparent green I first had.
>   > 
>   > The other day, I was cleaning a board using water and: the clear 
>   > green solution!... I made the experiment of adding water to a sample 
>   > of the etchant and it did change color and turned clear green. The 
>   > only problem is: it didn't etch, at least not fast enough for me to 
>   > notice.
>   > 
>   > Now, I don't know enough about chemistry to figure this out, but is 
>   > it possible that if I add copper and do the bubbling, that it'll turn 
>   > clear green again? I mean, I think there's too much HCl and not 
>   > enough of the other stuff!
>   > 
>   > Thanks,
>   > Fp
>   > www.tonepad.com
>   > 
>   > 
>   > 
>   > Be sure to visit the group home and check for new Bookmarks and files:
>   > http://groups.yahoo.com/group/Homebrew_PCBs
>   > 
>   > To unsubscribe from this group, send an email to:
>   > Homebrew_PCBs-unsubscribe@yahoogroups.com
>   > 
>   >  
>   > 
>   > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>   > 
>   > 
> 
> 
> 
>         Yahoo! Groups Sponsor 
>        
>        
> 
>   Be sure to visit the group home and check for new Bookmarks and files:
>   http://groups.yahoo.com/group/Homebrew_PCBs
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> 
> 
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> 
> 
> 
> [Non-text portions of this message have been removed]
> 
> 
> 
> Be sure to visit the group home and check for new Bookmarks and files:
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>

Re: [Homebrew_PCBs] Home made etchant

2003-04-28 by Francisco Peña

That makes it all more clear, thanks!

I just used some of this regenerated etchant and it's working fine, only it takes a little longer for the board to etch, but it's nothing compared to not having to buy any more or throw this stuff away!

Thanks!
Fp
www.tonepad.com
Show quoted textHide quoted text
  ----- Original Message ----- 
  From: Adam Seychell 
  To: Homebrew_PCBs@yahoogroups.com 
  Sent: Sunday, April 27, 2003 10:17 PM
  Subject: Re: [Homebrew_PCBs] Home made etchant


  CuCl is copper(I) chloride, it is almost insoluble in water. When 
    chloride ion concentrations is sufficient (e.g. from HCl or 
  CuCl2 or NaCl ect.) the solubility increases because copper(I) 
  complexes with chloride ions. This complexed form of copper(I) 
  chloride is dark brown. It doesn't take much concentration of 
  copper(I) chloride complex to make it appear opaque.

  CuCl2 is copper(II) chloride and is very soluble in water. At low 
  concentration the color is pale blue, at higher concentration it 
  goes clear green, and gets darker green as concentration 
  increases. At typical concentrations used for etching the 
  copper(II) chloride is a very dark green , that you cannot see 
  through more than 1 inch when looking through a bright light. If 
  the splashes on the side of the container look clear green then 
  its pretty much all copper(II) chloride and very little copper(I) 
  chloride. You can be sure that regeneration is completed.


  Francisco Peña wrote:
  > You say that the solution is brown because CuCl is present diluted in the etchant, and this can only happen when the chloride ion concentration is high, right?
  > 
  > And the way to get the etchant *right* is to bubble it a lot. Meaning I don't have to add more copper or water? (the etchant works as it is right now, btw)
  > 
  > About the look of the regenerated etchant: You mention deep green, I can see some green going on, at the sides of the tank where etchant has splashed, but the rest of the etchant is dark brown. Is it supposed to be clear in the end or not? If I pick up a drop of it in a piece of paper tissue it stains it green.
  > 
  > Thanks
  > Fp
  > 
  > 
  >   ----- Original Message ----- 
  >   From: Adam Seychell 
  >   To: Homebrew_PCBs@yahoogroups.com 
  >   Sent: Sunday, April 27, 2003 8:06 PM
  >   Subject: Re: [Homebrew_PCBs] Home made etchant
  > 
  > 
  >   I've seen what you have just described. What you are doing when 
  >   adding water to a dark solution of CuCl2 and some CuCl is the 
  >   CuCl precipitates out as what solid on dilution, thus leaving 
  >   only green CuCl2. The CuCl is only soluble (which makes the 
  >   solution dark brown) when the chloride ion concentration is high.
  >   Diluting will of course also reduce the concentration of CuCl2 
  >   and slow down etching rate.
  > 
  >   If you bubble enough air through the solution it *WILL* 
  >   eventually go deep green. Put a drop on a white piece of plastic 
  >   and come back in a few hours, if turns clear green then it means 
  >   the solution is not complete regenerated. Fine bubbles are many 
  >   times more efficient at regeneration than large bubbles. Aquarium 
  >   airstones are ideal. It can take an hour or more of vigorous 
  >   bubbling.
  > 
  >   Adam.
  > 
  >   frajopea wrote:
  >   > Hello,
  >   > 
  >   > I've been reading for a few weeks now, this is my first post.
  >   > 
  >   > There was a post about regenerating FeCl using HCl, I had a bunch of 
  >   > used up and very rusty etchant lying around so I did it. I poured HCl 
  >   > in the used etchant and the result was a very nice clear green/bluish 
  >   > solution that etched boards again. I was impressed.
  >   > 
  >   > Then there was the CuCl2 thread, where you just use copper, HCl and 
  >   > H2O...
  >   > 
  >   > With all this in mind, I kept using my regenerated etchant and 
  >   > pouring some HCl every now and then when it started to look brown. 
  >   > The thing is, now the etchant is brown, no matter how much HCl I put 
  >   > in it, I can't get it back to the clear transparent green I first had.
  >   > 
  >   > The other day, I was cleaning a board using water and: the clear 
  >   > green solution!... I made the experiment of adding water to a sample 
  >   > of the etchant and it did change color and turned clear green. The 
  >   > only problem is: it didn't etch, at least not fast enough for me to 
  >   > notice.
  >   > 
  >   > Now, I don't know enough about chemistry to figure this out, but is 
  >   > it possible that if I add copper and do the bubbling, that it'll turn 
  >   > clear green again? I mean, I think there's too much HCl and not 
  >   > enough of the other stuff!
  >   > 
  >   > Thanks,
  >   > Fp
  >   > www.tonepad.com
  >   > 
  >   > 
  >   > 
  >   > Be sure to visit the group home and check for new Bookmarks and files:
  >   > http://groups.yahoo.com/group/Homebrew_PCBs
  >   > 
  >   > To unsubscribe from this group, send an email to:
  >   > Homebrew_PCBs-unsubscribe@yahoogroups.com
  >   > 
  >   >  
  >   > 
  >   > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
  >   > 
  >   > 
  > 
  > 
  > 
  >         Yahoo! Groups Sponsor 
  >        
  >        
  > 
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  > 
  > 
  > 
  > [Non-text portions of this message have been removed]
  > 
  > 
  > 
  > Be sure to visit the group home and check for new Bookmarks and files:
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  > 



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

good phenol red source for analysis

2003-04-28 by Stefan Trethan

hi

i just had a idea while i was looking for H2O2 in pool supply.
I didn't find anything today in a shop who carries pool chemicals.
so i had another look with google and found out that phenol red is sold as these small tablettes which 
are simply thrown in the pool water sample.

i have some of them left here and i think this is a convenient source for anybody who has no access to 
distinct chemical supplies. i believe this pool chemicals can be bought anywhere.
if there is some disadvantage (other than maybe the higher prize as you can use smaller amounts from a 
bottle) please tell me.


i also discovered a h2o2 source.
NEPTUTOP is 25% H2O2
and there are also other brands like "hobby-top" (local one i think).

i have no price for neptutop but 5 liters 35% hobby-top h2o2 costs 20eur.
this is much below the price i pay for it as lab chemical (i remember ~~10 eur for only 250ml).
i also hope it has more stabilizer in.

i really believe with this cost / etch i won't start the bubbling campaign.
this seems much to high effort (concerning the corrosive fuem discussion also).
and also the etch time is much lower with fresh peroxyde in there.

i think anyone can find a h2o2 pool additive where he is, sold under different brands.

regards
st

CuCL too much effort ?

2003-04-29 by grantfair2001

To put the HCl fume problem in perspective - I had been bubbling the
etchamt solution with an open tank for over a week without any HCL
damage, even on steel a few feet away.

It was only when I started aerating with a much higher volume pump
that the problem appeared. The etchant surface was so agitated that it
was spitting some etchant out of the tank - and into the air. And the
bigger compressor got warm enough that the air was being warmed, and
increasing the temperature of the etchant. I understand a higher
temperature alone may cause fuming.

I believe the CuCl approach can be used without any fume damage, even
without a fume exhaust.

As to the slow process, this is in part due to my air sparger making
largish bubbles. If I got an aquarium air stone the process would
probably be much faster.

Grant

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
<stefan_trethan@g...> wrote:

> i really believe with this cost / etch i won't start the bubbling
campaign.
> this seems much to high effort (concerning the corrosive fuem
discussion also).
> regards
> st

Re: [Homebrew_PCBs] CuCL too much effort ?

2003-04-29 by Adam Seychell

I cannot pinpoint why its slow. As I posted ealier I got a piece 
of clean copper in fresh 20% HCl and completely dissolved it in 
little over 3 hours to end up with deep green colored solution. 
You can see from the picture that air supply was extremely 
vigorous so the test dosn't represent a practical situation. It 
became warm (20\ufffdC above ambient) during its peak because of the 
heat generated by the reaction. Unfortunately its been a slow 
week with your setup, and I can understand your frustration.

I haven't yet done a direct comparison between the use of large 
bubbles and fine bubbles and how it effects the reaction rate. 
Maybe there is a 100:1 difference ???. On a more theoretical 
thought, the surface area/volume ratio of a bubble (assuming 
perfect sphere) is proportional to 1/r. For equal volume of air 1 
mm bubbles would give 10 times surface area than 10 mm bubbles.
Any foaming on the surface would also dramatically increase air 
contact area. Small bubbles are much more effective at creating 
foam than large bubbles.

Its expected for splashes to jump out of the tank, you should 
have a lid on. Virtually all the oxygen source is from the air 
bubbles, not the surrounding air.

Adam

grantfair2001 wrote:
Show quoted textHide quoted text
> To put the HCl fume problem in perspective - I had been bubbling the
> etchamt solution with an open tank for over a week without any HCL
> damage, even on steel a few feet away.
> 
> It was only when I started aerating with a much higher volume pump
> that the problem appeared. The etchant surface was so agitated that it
> was spitting some etchant out of the tank - and into the air. And the
> bigger compressor got warm enough that the air was being warmed, and
> increasing the temperature of the etchant. I understand a higher
> temperature alone may cause fuming.
> 
> I believe the CuCl approach can be used without any fume damage, even
> without a fume exhaust.
> 
> As to the slow process, this is in part due to my air sparger making
> largish bubbles. If I got an aquarium air stone the process would
> probably be much faster.
> 
> Grant
> 
> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> <stefan_trethan@g...> wrote:
> 
> 
>>i really believe with this cost / etch i won't start the bubbling
> 
> campaign.
> 
>>this seems much to high effort (concerning the corrosive fuem
> 
> discussion also).
> 
>>regards
>>st
> 
> 
> 
> 
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
> 
>  
> 
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
> 
>

Re: [Homebrew_PCBs] CuCL too much effort ?

2003-04-29 by Mike Putnam

What effect does heat have on the HCl etchant? My Ferric Chloride tank uses
aeration as well as heat for a fast etch. Can you get a faster reaction by
heating the HCl or is there an inherent danger to doing this?

-Mike

----- Original Message -----
From: "Adam Seychell" <adam_seychell@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, April 28, 2003 11:59 PM
Subject: Re: [Homebrew_PCBs] CuCL too much effort ?


> I cannot pinpoint why its slow. As I posted ealier I got a piece
> of clean copper in fresh 20% HCl and completely dissolved it in
> little over 3 hours to end up with deep green colored solution.
> You can see from the picture that air supply was extremely
> vigorous so the test dosn't represent a practical situation. It
> became warm (20\ufffdC above ambient) during its peak because of the
> heat generated by the reaction. Unfortunately its been a slow
> week with your setup, and I can understand your frustration.
>
> I haven't yet done a direct comparison between the use of large
> bubbles and fine bubbles and how it effects the reaction rate.
> Maybe there is a 100:1 difference ???. On a more theoretical
> thought, the surface area/volume ratio of a bubble (assuming
> perfect sphere) is proportional to 1/r. For equal volume of air 1
> mm bubbles would give 10 times surface area than 10 mm bubbles.
> Any foaming on the surface would also dramatically increase air
> contact area. Small bubbles are much more effective at creating
> foam than large bubbles.
>
> Its expected for splashes to jump out of the tank, you should
> have a lid on. Virtually all the oxygen source is from the air
> bubbles, not the surrounding air.
>
> Adam
>
> grantfair2001 wrote:
> > To put the HCl fume problem in perspective - I had been bubbling the
> > etchamt solution with an open tank for over a week without any HCL
> > damage, even on steel a few feet away.
> >
> > It was only when I started aerating with a much higher volume pump
> > that the problem appeared. The etchant surface was so agitated that it
> > was spitting some etchant out of the tank - and into the air. And the
> > bigger compressor got warm enough that the air was being warmed, and
> > increasing the temperature of the etchant. I understand a higher
> > temperature alone may cause fuming.
> >
> > I believe the CuCl approach can be used without any fume damage, even
> > without a fume exhaust.
> >
> > As to the slow process, this is in part due to my air sparger making
> > largish bubbles. If I got an aquarium air stone the process would
> > probably be much faster.
> >
> > Grant
> >
> > --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> > <stefan_trethan@g...> wrote:
> >
> >
> >>i really believe with this cost / etch i won't start the bubbling
> >
> > campaign.
> >
> >>this seems much to high effort (concerning the corrosive fuem
> >
> > discussion also).
> >
> >>regards
> >>st
> >
> >
> >
> >
> > Be sure to visit the group home and check for new Bookmarks and files:
> > http://groups.yahoo.com/group/Homebrew_PCBs
> >
> > To unsubscribe from this group, send an email to:
> > Homebrew_PCBs-unsubscribe@yahoogroups.com
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
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> >
> >
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

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