Homebrew PCBs

Can someone here PLEASE outline the procedure and chemistry to  use for this 
etch-method?  I have never seen ANYWHERE a list like, 
"1.  Boil the bare blank in swamp-water;
  2.  Incant;
  3.  Swish the board around in a 30% CuCl solution  over 80°C for 15 minutes;
  4,  Etc. etc."
 
With FeCl, you can omit steps 2. and 4., and the result is  fine, but messy.  
 
Please?
 


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

On Sat, 20 Aug 2005 02:38:22 +0200, <JanRwl@...> wrote:

> Can someone here PLEASE outline the procedure and chemistry to  use for  
> this
> etch-method?  I have never seen ANYWHERE a list like,
> "1.  Boil the bare blank in swamp-water;
>   2.  Incant;
>   3.  Swish the board around in a 30% CuCl solution  over 80\ufffdC for 15  
> minutes;
>   4,  Etc. etc."
> With FeCl, you can omit steps 2. and 4., and the result is  fine, but  
> messy.
> Please?


I'll try.
Let's divide that into 3 parts:
Etching boards, maintainance, and first "brewing" of CuCl.


For normal etching, you'd need to do nothing much. You'd just put a board  
in, and add H2O2 if the etchant is too dark in color. a few ml is enough  
to oxidize it. The color is all you need to determine if it is ok or needs  
something. Then you turn on the bubbler and simply wait until done.  
Nothing needs to be done after etching.

The adding of hydrogen peroxide (H2O2) takes the hydrogen away from some  
of the hydrochloric acid (HCl). That means the chlorine is freed and can  
"take" one copper from Cu2Cl (the dark brown stuff) to form more CuCl  
(light green), and water. CuCl is now prepared to take a second copper  
again, thus etch the board. You can also introduce the oxygen from other  
sources, like pumping air through it (takes long), or even chlorine gas  
directly, but that's poisonous.


maintainance:
 From time to time you might want to measure the molarity of the HCl in  
there. That is, how many hydrochloric acid is still "free" (not carrying  
copper) and can be used to form CuCl. Because every time you add H2O2 some  
of the HCl is converted into CuCl. At some point, if all HCl is used up,  
adding H2O2 will not bring on the expected brigtening of the etchant and  
increase in etch speed. Also, the etchant will have a bluish color ad  
deposit a blue sludge on boards. This is a sure indicator there is not  
enough HCl, but you sould have added some by then.

To measure the HCl molarity, you need 4 things. A alkaline solution of  
known molarity (NaOH), some indicator (like methylorange), and two  
eyedroppers. You can get your NaOH solution by solving a weighed amount of  
developer in water. It should be a 1 molar solution. How much you need to  
weigh is said in one of the pages in the links section. When you have that  
the procedure is simple. Put 10 drops of etchant in a small container, add  
some water if you like, and one drop of indicator. It's now orange. Then  
add the alkaline solution drop by drop, all the time swishing the  
container to mix it. When it turns green stop and your number of alkaline  
solution drops added is your molarity after dividing by 10.
I don't do that often, and usually only add HCl by feel. A wide range of  
molarity will be ok. I keep it around 1. Still every few months i feel  
like checking the molarity.

There's also the density to be measured. Adding the copper makes the  
etchant more "heavy". In a away this is good - because you'll have more  
CuCl do do the etching. But if it gets too much you need to remove some  
etchant and add water. I have never encountered this, i guess the water in  
the HCl and H2O2 added is enough. You can measure the density with a  
hydrometer, which you can simply by in a car parts store, as a tool for  
checking car battery acid. It comes in a neat huge "eyedropper" in which  
the hydrometer swims.


First brewing:
Some tutorials call for adding copper in some form.
I have found you can start just as well with only HCl and H2O2, and water.
At first, you don't have any CuCl, but those two chemicals will etch all  
by themself. You can make etchant up by diluting HCl to about 10% and  
adding a swig of H2O2. Then put in the board and go by color.
At first there is none or little CuCl, so you have to add some H2O2 each  
time you etch. As copper content increases you get more and more CuCl,  
which does the etching and must only be re-oxidized from time to time. I'm  
now at a stage where i need to add H2O2 maybe each third or fourth board.

Here you go.

ST

JanRwl@... wrote:
> Can someone here PLEASE outline the procedure and chemistry to  use for this 
> etch-method?  I have never seen ANYWHERE a list like, 
> "1.  Boil the bare blank in swamp-water;
>   2.  Incant;
>   3.  Swish the board around in a 30% CuCl solution  over 80\ufffdC for 15 minutes;
>   4,  Etc. etc."
>  
> With FeCl, you can omit steps 2. and 4., and the result is  fine, but messy.  
>  
> Please?
>  
> 

There's  two main approaches to chloride etching chemistry.

1) CuCl2 + HCl + H2O2
2) CuCl2 + HCl + O2

Method 1)is much faster than 2). I use 2) at room temp, which is about 2 
to 3 times slower than FeCl3 at same temperature. For 1) you don't 
actually need CuCl2, but helps, and its a byproduct so you get it for 
free. Most reliable determination of CuCl concentration is by density 
measurement, and should be 1.30 to 1.45 g/cm^3, yes, very concentrated 
solution needed for method 1), or else its too damn slow. HCl should 
also be > 1 Molar (4% wt) for speed. Ball park figure of HCl content is 
easily found by taking a 1cm^3 graduated diabetic syringe filled with 
1.0 cm^3 of 40g/Liter NaOH. Add drop wise to small clear jar filled with 
1.0 cm^3 sample from etchant + 1 table spoon of water. When copper 
hydroxide precipitate forms, stop, stir, and continue additions if 
precipitate redissolves. When precipitate stops dissolving then HCl 
concentration = X Molar, where X is cm^3 of NaOH solution added. You 
need access to some scales measurable in gram units in order to prepare 
40g/L NaOH solution.

Adam Seychell wrote:
> 
> ... 
> measurement, and should be 1.30 to 1.45 g/cm^3, yes, very concentrated 
> solution needed for method 1), or else its too damn slow. "...

correction: high CuCl concentration is only required for method 2).

Ich bedanke mich!  Mal schauen . .  .


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

Thanks.  MUCH too complex for a non-Chem.E.  !!!


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

On Sun, 21 Aug 2005 04:43:49 +0200, <JanRwl@...> wrote:

> Thanks.  MUCH too complex for a non-Chem.E.  !!!


not really.

As said, i only do the molarity check every few months when i feel like  
it, 'cause i just add stuff by color and etching speed. I don't understand  
anything about chemistry, and how i described it is how i imagine it, i'm  
not sure it is chemically correct, but it is a theory that explains what  
is happening so it's good enough for me.
You can do it easily if you want.

ST

--- In Homebrew_PCBs@yahoogroups.com, JanRwl@A... wrote:
> Thanks.  MUCH too complex for a non-Chem.E.  !!!
> 
> 
> [Non-text portions of this message have been removed]

I don't think it really needs that much chemistry background and is
about at the level of complexity of baking a cake from scratch. 

However, It's just not something I wanted to do.  I tried it with
mixed results and went back to AP.  Its the most expensive of FeCL, AP
and CuCl and has the downsides that have been noted but its clean and
easy.  If you can use FeCl, you can use AP.

Phil

On Sun, 21 Aug 2005 19:41:32 +0200, Phil <phil1960us@...> wrote:

>
> I don't think it really needs that much chemistry background and is
> about at the level of complexity of baking a cake from scratch.

I'd say it's definitely easier! I mean i can't bake a cake, maybe some  
shortbread but that's about it.... well... maybe with a manual..

ST

Okay, starting to make some sense.  But, finding and buying 
chemicals isn't the easiest thing to do these days.

So, a couple of follow up questions.....


hydrogen peroxide (H2O2), is this the same as what I can purchase at 
the local drug store? Or, is there a stronger solution or something 
I have to get at a specialty supplier?


hydrochloric acid (HCl), I know I have seen this for some purposes 
but can't recall common uses - toilet bowl cleaner perhaps?  Again, 
where would I purchase this, and is there a certain strength I 
should look for?


With this chemical make up, do you still want to use a heater?

Does anyone know which plastics will be okay to use as a tank for 
this type of etching? I was thinking of using Acrylics, but that 
stuff can be a pain in the ass to glue up good.  Then I thought 
about polystyrene which you can get translucent and I believe it can 
be glued up more readily.

TIA, I am getting closer to understanding it :-)

Chris














--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
> On Sat, 20 Aug 2005 02:38:22 +0200, <JanRwl@A...> wrote:
> 
> > Can someone here PLEASE outline the procedure and chemistry to  
use for  
> > this
> > etch-method?  I have never seen ANYWHERE a list like,
> > "1.  Boil the bare blank in swamp-water;
> >   2.  Incant;
> >   3.  Swish the board around in a 30% CuCl solution  over 80°C 
for 15  
> > minutes;
> >   4,  Etc. etc."
> > With FeCl, you can omit steps 2. and 4., and the result is  
fine, but  
> > messy.
> > Please?
> 
> 
> I'll try.
> Let's divide that into 3 parts:
> Etching boards, maintainance, and first "brewing" of CuCl.
> 
> 
> For normal etching, you'd need to do nothing much. You'd just put 
a board  
> in, and add H2O2 if the etchant is too dark in color. a few ml is 
enough  
> to oxidize it. The color is all you need to determine if it is ok 
or needs  
> something. Then you turn on the bubbler and simply wait until 
done.  
> Nothing needs to be done after etching.
> 
> The adding of hydrogen peroxide (H2O2) takes the hydrogen away 
from some  
> of the hydrochloric acid (HCl). That means the chlorine is freed 
and can  
> "take" one copper from Cu2Cl (the dark brown stuff) to form more 
CuCl  
> (light green), and water. CuCl is now prepared to take a second 
copper  
> again, thus etch the board. You can also introduce the oxygen from 
other  
> sources, like pumping air through it (takes long), or even 
chlorine gas  
> directly, but that's poisonous.
> 
> 
> maintainance:
>  From time to time you might want to measure the molarity of the 
HCl in  
> there. That is, how many hydrochloric acid is still "free" (not 
carrying  
> copper) and can be used to form CuCl. Because every time you add 
H2O2 some  
> of the HCl is converted into CuCl. At some point, if all HCl is 
used up,  
> adding H2O2 will not bring on the expected brigtening of the 
etchant and  
> increase in etch speed. Also, the etchant will have a bluish color 
ad  
> deposit a blue sludge on boards. This is a sure indicator there is 
not  
> enough HCl, but you sould have added some by then.
> 
> To measure the HCl molarity, you need 4 things. A alkaline 
solution of  
> known molarity (NaOH), some indicator (like methylorange), and 
two  
> eyedroppers. You can get your NaOH solution by solving a weighed 
amount of  
> developer in water. It should be a 1 molar solution. How much you 
need to  
> weigh is said in one of the pages in the links section. When you 
have that  
> the procedure is simple. Put 10 drops of etchant in a small 
container, add  
> some water if you like, and one drop of indicator. It's now 
orange. Then  
> add the alkaline solution drop by drop, all the time swishing the  
> container to mix it. When it turns green stop and your number of 
alkaline  
> solution drops added is your molarity after dividing by 10.
> I don't do that often, and usually only add HCl by feel. A wide 
range of  
> molarity will be ok. I keep it around 1. Still every few months i 
feel  
> like checking the molarity.
> 
> There's also the density to be measured. Adding the copper makes 
the  
> etchant more "heavy". In a away this is good - because you'll have 
more  
> CuCl do do the etching. But if it gets too much you need to remove 
some  
> etchant and add water. I have never encountered this, i guess the 
water in  
> the HCl and H2O2 added is enough. You can measure the density with 
a  
> hydrometer, which you can simply by in a car parts store, as a 
tool for  
> checking car battery acid. It comes in a neat huge "eyedropper" in 
which  
> the hydrometer swims.
> 
> 
> First brewing:
> Some tutorials call for adding copper in some form.
> I have found you can start just as well with only HCl and H2O2, 
and water.
> At first, you don't have any CuCl, but those two chemicals will 
etch all  
> by themself. You can make etchant up by diluting HCl to about 10% 
and  
> adding a swig of H2O2. Then put in the board and go by color.
> At first there is none or little CuCl, so you have to add some 
H2O2 each  
> time you etch. As copper content increases you get more and more 
CuCl,  
> which does the etching and must only be re-oxidized from time to 
time. I'm  
> now at a stage where i need to add H2O2 maybe each third or fourth 
board.

> 
> Here you go.
> 
> ST

In a message dated 8/21/2005 12:42:51 P.M. Central Daylight Time,  
phil1960us@... writes:

If you  can use FeCl, you can use AP.




OK, Phil; I'm open to that!  Then, same question to  AP.  Where do you get 
it?  How many gm. of AP to a liter of  water?  Heated to mix?  Warmed to use??  
Can it be "regenerated",  or is it spent, once it "quits the first  time"?     
     Jan  R.


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

You can get 30% HCL cheap - home depot.  its used for acid rinse on
masonary. 

The H2O2 from the drug store (3%) isn't strong enough except perhaps
for the initial creation of the mix.  I got mine (35%) from a
scientific supply place but it was way too expensive.  I have heard of
people getting stronger H2O2 from drugstores but none in my area carry
anything other than 3%.  I'm sure Chicago must have some source of
reasonably priced H2O2.

Acrylic is very easy to glue.  Cutting is tricky, though.   Get the
special knife and it goes much easier.

I have about 2 quarts of CuCl in a cereal container - its holding up
ok.  HDPE.  

By the way, anyone want my CuCl?  Seattle area pickup.  free.

Chris, you really should at least look at Ammonium Persulphate.   For
casual etching, it really is a great way to go.

Phil

--- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing"
<lcdpublishing@y...> wrote:

> Okay, starting to make some sense.  But, finding and buying 
> chemicals isn't the easiest thing to do these days.
> 
> So, a couple of follow up questions.....
> 
> 
> hydrogen peroxide (H2O2), is this the same as what I can purchase at 
> the local drug store? Or, is there a stronger solution or something 
> I have to get at a specialty supplier?
> 
> 
> hydrochloric acid (HCl), I know I have seen this for some purposes 
> but can't recall common uses - toilet bowl cleaner perhaps?  Again, 
> where would I purchase this, and is there a certain strength I 
> should look for?
> 
> 
> With this chemical make up, do you still want to use a heater?
> 
> Does anyone know which plastics will be okay to use as a tank for 
> this type of etching? I was thinking of using Acrylics, but that 
> stuff can be a pain in the ass to glue up good.  Then I thought 
> about polystyrene which you can get translucent and I believe it can 
> be glued up more readily.
> 
> TIA, I am getting closer to understanding it :-)
> 
> Chris
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> --- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
> <stefan_trethan@g...> wrote:
> > On Sat, 20 Aug 2005 02:38:22 +0200, <JanRwl@A...> wrote:
> > 
> > > Can someone here PLEASE outline the procedure and chemistry to  
> use for  
> > > this
> > > etch-method?  I have never seen ANYWHERE a list like,
> > > "1.  Boil the bare blank in swamp-water;
> > >   2.  Incant;
> > >   3.  Swish the board around in a 30% CuCl solution  over 80°C 
> for 15  
> > > minutes;
> > >   4,  Etc. etc."
> > > With FeCl, you can omit steps 2. and 4., and the result is  
> fine, but  
> > > messy.
> > > Please?
> > 
> > 
> > I'll try.
> > Let's divide that into 3 parts:
> > Etching boards, maintainance, and first "brewing" of CuCl.
> > 
> > 
> > For normal etching, you'd need to do nothing much. You'd just put 
> a board  
> > in, and add H2O2 if the etchant is too dark in color. a few ml is 
> enough  
> > to oxidize it. The color is all you need to determine if it is ok 
> or needs  
> > something. Then you turn on the bubbler and simply wait until 
> done.  
> > Nothing needs to be done after etching.
> > 
> > The adding of hydrogen peroxide (H2O2) takes the hydrogen away 
> from some  
> > of the hydrochloric acid (HCl). That means the chlorine is freed 
> and can  
> > "take" one copper from Cu2Cl (the dark brown stuff) to form more 
> CuCl  
> > (light green), and water. CuCl is now prepared to take a second 
> copper  
> > again, thus etch the board. You can also introduce the oxygen from 
> other  
> > sources, like pumping air through it (takes long), or even 
> chlorine gas  
> > directly, but that's poisonous.
> > 
> > 
> > maintainance:
> >  From time to time you might want to measure the molarity of the 
> HCl in  
> > there. That is, how many hydrochloric acid is still "free" (not 
> carrying  
> > copper) and can be used to form CuCl. Because every time you add 
> H2O2 some  
> > of the HCl is converted into CuCl. At some point, if all HCl is 
> used up,  
> > adding H2O2 will not bring on the expected brigtening of the 
> etchant and  
> > increase in etch speed. Also, the etchant will have a bluish color 
> ad  
> > deposit a blue sludge on boards. This is a sure indicator there is 
> not  
> > enough HCl, but you sould have added some by then.
> > 
> > To measure the HCl molarity, you need 4 things. A alkaline 
> solution of  
> > known molarity (NaOH), some indicator (like methylorange), and 
> two  
> > eyedroppers. You can get your NaOH solution by solving a weighed 
> amount of  
> > developer in water. It should be a 1 molar solution. How much you 
> need to  
> > weigh is said in one of the pages in the links section. When you 
> have that  
> > the procedure is simple. Put 10 drops of etchant in a small 
> container, add  
> > some water if you like, and one drop of indicator. It's now 
> orange. Then  
> > add the alkaline solution drop by drop, all the time swishing the  
> > container to mix it. When it turns green stop and your number of 
> alkaline  
> > solution drops added is your molarity after dividing by 10.
> > I don't do that often, and usually only add HCl by feel. A wide 
> range of  
> > molarity will be ok. I keep it around 1. Still every few months i 
> feel  
> > like checking the molarity.
> > 
> > There's also the density to be measured. Adding the copper makes 
> the  
> > etchant more "heavy". In a away this is good - because you'll have 
> more  
> > CuCl do do the etching. But if it gets too much you need to remove 
> some  
> > etchant and add water. I have never encountered this, i guess the 
> water in  
> > the HCl and H2O2 added is enough. You can measure the density with 
> a  
> > hydrometer, which you can simply by in a car parts store, as a 
> tool for  
> > checking car battery acid. It comes in a neat huge "eyedropper" in 
> which  
> > the hydrometer swims.
> > 
> > 
> > First brewing:
> > Some tutorials call for adding copper in some form.
> > I have found you can start just as well with only HCl and H2O2, 
> and water.
> > At first, you don't have any CuCl, but those two chemicals will 
> etch all  
> > by themself. You can make etchant up by diluting HCl to about 10% 
> and  
> > adding a swig of H2O2. Then put in the board and go by color.
> > At first there is none or little CuCl, so you have to add some 
> H2O2 each  
> > time you etch. As copper content increases you get more and more 
> CuCl,  
> > which does the etching and must only be re-oxidized from time to 
> time. I'm  
> > now at a stage where i need to add H2O2 maybe each third or fourth 
> board.
> > 
> > Here you go.
> > 
> > ST

On Sun, 21 Aug 2005 22:10:56 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

>
> hydrogen peroxide (H2O2), is this the same as what I can purchase at
> the local drug store? Or, is there a stronger solution or something
> I have to get at a specialty supplier?

often the drug store stuff is only 3%, you want around 30% or you add too  
much water.

> hydrochloric acid (HCl), I know I have seen this for some purposes
> but can't recall common uses - toilet bowl cleaner perhaps?  Again,
> where would I purchase this, and is there a certain strength I
> should look for?

Around 30% is a common strength again, it has many uses, cleaning stuff  
like bricks, toilets, ...

I get both chemicals at my chemists shop. I don't remember the price  
exactly, but it is well below 10eur for a liter each, and that lasts you  
quite a while.


> With this chemical make up, do you still want to use a heater?

NO! HCl will form vapor somewhere low, around 50C, and even below it will  
create much more fumes when heated.

> Does anyone know which plastics will be okay to use as a tank for
> this type of etching? I was thinking of using Acrylics, but that
> stuff can be a pain in the ass to glue up good.  Then I thought
> about polystyrene which you can get translucent and I believe it can
> be glued up more readily.

Use glass. easier to cut and cheaper too.
Some plastics like lexan are said to be no good 'cause they take up water  
(etchant). I had it in a PET bottle the first year or so, ad it did go  
"through" that (salts on outside of bottle).
glued with RTV silicone holds up very well.


I've just boken the blade of my nibbler pliers stupidly. At the moment i'm  
still supressing thinking of it but i'll have to come to terms with it in  
a few minutes. Those are so darn expensive... I really didn't need that.

ST

--- In Homebrew_PCBs@yahoogroups.com, JanRwl@A... wrote:
> OK, Phil; I'm open to that!  Then, same question to  AP.  Where do
you get 
> it?  How many gm. of AP to a liter of  water?  Heated to mix? 
Warmed to use??  
> Can it be "regenerated",  or is it spent, once it "quits the first 
time"?     
>      Jan  R.

I've purchased it from CSI mail order for $18.
http://www.circuitspecialists.com/prod.itml/icOid/2825
I got my last Kg from Fry's - it was about $14.  250 grams per liter
of water.  It lasts for probably 15-20 moderate sized boards.  I don't
know if it can be regenerated.  I heat it to about 120 F via a hacked
aquarium heater and "dimmer" control.  I really should build a temp
controller someday...

Because it's clear and doesn't stain, it is 10x better than FeCl.  I
hate that stuff.  Here's a picture of my tank with AP in it.  The
stuff in the bottom disolves when I heat it. 
http://www.geocities.com/pcbs4less/tank/DSCN5374.JPG

Phil

In a message dated 8/21/2005 7:18:58 P.M. Central Daylight Time,  
phil1960us@... writes:

Here's a  picture of my tank with AP in it. 


HUGE, virtually black.  Can't you reduce the  color-saturation and make it 
80% smaller  ("20%R")?


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

it views fine on several other PCs (not black at all).  Yeah, its big,
guess I could reduce it.

--- In Homebrew_PCBs@yahoogroups.com, JanRwl@A... wrote:
>  
> In a message dated 8/21/2005 7:18:58 P.M. Central Daylight Time,  
> phil1960us@y... writes:
> 
> Here's a  picture of my tank with AP in it. 
> 
> 
> HUGE, virtually black.  Can't you reduce the  color-saturation and
make it 

> 80% smaller  ("20%R")?
> 
> 
> [Non-text portions of this message have been removed]

Stefan Trethan wrote:
> On Sun, 21 Aug 2005 22:10:56 +0200, lcdpublishing  
> <lcdpublishing@...> wrote:
> 
> 
>>hydrogen peroxide (H2O2), is this the same as what I can purchase at
>>the local drug store? Or, is there a stronger solution or something
>>I have to get at a specialty supplier?
> 
> 
> often the drug store stuff is only 3%, you want around 30% or you add too  
> much water.
> 
> 
>>hydrochloric acid (HCl), I know I have seen this for some purposes
>>but can't recall common uses - toilet bowl cleaner perhaps?  Again,
>>where would I purchase this, and is there a certain strength I
>>should look for?
> 
> 
> Around 30% is a common strength again, it has many uses, cleaning stuff  
> like bricks, toilets, ...
> 
> I get both chemicals at my chemists shop. I don't remember the price  
> exactly, but it is well below 10eur for a liter each, and that lasts you  
> quite a while.
> 
> 


Another possible place to get > %10 H2O2 is a hairdressers supplier. I 
think the one near me sold it up to 18%. Anyone had problems with this 
stiff decomposing over time ?

> Use glass. easier to cut and cheaper too.
> Some plastics like lexan are said to be no good 'cause they take 
up water  
> (etchant). I had it in a PET bottle the first year or so, ad it 
did go  
> "through" that (salts on outside of bottle).
> glued with RTV silicone holds up very well.
> 
> 
> I've just boken the blade of my nibbler pliers stupidly. At the 
moment i'm  
> still supressing thinking of it but i'll have to come to terms 
with it in  
> a few minutes. Those are so darn expensive... I really didn't need 
that.


Working with glass isn't too much of a problem for me. My wife and I 
have done some stained glass work so I have the basic tools.

You are correct, many plastics will take on moisture which is why I 
was concerned about using that.  The glass worried me due to getting 
good seals with silicone. Did you use an "Under water" rated 
silicone, or just any old silicone adhesive?  Did you apply the 
silicone on the outside of the tank or the inside?  Inside could be 
a bit of a problem reaching in, so I was thinking of doing it from 
the outside - just cut the pieces so there is overlap to work with.

Chris

On Mon, 22 Aug 2005 17:56:39 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

>
> You are correct, many plastics will take on moisture which is why I
> was concerned about using that.  The glass worried me due to getting
> good seals with silicone. Did you use an "Under water" rated
> silicone, or just any old silicone adhesive?  Did you apply the
> silicone on the outside of the tank or the inside?  Inside could be
> a bit of a problem reaching in, so I was thinking of doing it from
> the outside - just cut the pieces so there is overlap to work with.
> Chris


hi,

yes, glass is very quick to cut once you figured out how to do it.
I was told there is a similar (scoring and breaking) method for plastic,  
but haven't tried it. sawing it is a pain.

I used plain ol' bathroom silicone, acetic acid cure (best for glass).  
clean surfaces well beforehand.
My first glass tank i glued inside and out, with huge beads. I glued the  
indside using a hose on the silicone applicator, and lots of time ;-).  
There wasn't any sign of deterioration or "creeping" after several years.

The tank i use now was made much simpler after reading up on aquarium  
making, put a thin bead on the edge of the glass plate, and press it  
against the surface of the mating part. This is considered sufficient for  
an aquarium. I decided to put a bead on all outside edges too. Make sure  
to go around the edge of the sideplates where they contact the base plate,  
because if you don't the etchant might leak in the gap along the edge, if  
your bead there wasn't perfect. Happened to me, i had a tiny leak because  
i didn't "fill" this gap  properly, and didn't run all the way around  
either. simple fix, drained it and spot-repaired. Most stable construction  
appears to me to be with larger-than-needed sideplates, so you get all  
"iniside" edges on the outside... (pretty poor description, huh?).


I am still planning to make pictures for you, but only have the chance in  
two days time.



ST

On Mon, 22 Aug 2005 12:23:05 +0200, Adam Seychell  
<a_seychell@...> wrote:

>
> Another possible place to get > %10 H2O2 is a hairdressers supplier. I
> think the one near me sold it up to 18%. Anyone had problems with this
> stiff decomposing over time ?


another place is pool supply. it is 25% or so there and sold under some  
brand name here in europe i don't remember.

Most H2O2 appears to have stabilizers added. I am not sure what mine has,  
but haven't seen any change in a few years storage. Don't put in the sun.

ST