Homebrew PCBs

Hi all, Sodium Carbonate is sold quite cheaply as a swimming pool
additive to raise pH in swimming pool water, also known as Soda Ash.
The mixture I use is 7 grams to a liter of water. I use it with Riston
sensitised  board which looks to be the same type of sensitising that
has been discussed on this forum lately.
Don VK3YV....

--- In Homebrew_PCBs@yahoogroups.com, "don2822003" <vk3yv@...> wrote:
>
> Hi all, Sodium Carbonate is sold quite cheaply as a swimming pool
> additive to raise pH in swimming pool water, also known as Soda Ash.
> The mixture I use is 7 grams to a liter of water. I use it with Riston
> sensitised  board which looks to be the same type of sensitising that
> has been discussed on this forum lately.
> Don VK3YV....

It's even easier to get than that.  Just go to the grocery and buy
a box of "washing soda" (usually produced by Arm & Hammer here) [1].
Also, there's a way you can produce it from baking soda by baking
it.

[1] I'm not talking about detergent, but washing soda.

Dave

Besides kitchen salt there is no more common and cheap chemical then
Sodium Carbonate.
See also  http://en.wikipedia.org/wiki/Sodium_carbonate

But if concentration matters take care of the following:

If you get a fine powder it'll be Sodium carbonate Na2CO3
but you'll find also bags of "crystal soda" sold as washing soda,
which is also Na2CO3, the difference is, for every molecule of soda
there are 10 molecules of water attachted; so the formula of those 
crystal soda is Na2CO3.10H2O
If you find a formula who asks for 7grams/liter ( = 0.7% )soda,
you must add much more of the crystals then of the water free powder.

Comparable the prize/bath and the quality can be the same,
you just need to add more of the cheaper crystals.

Grts
Bruno M. ( a chemist)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--- In Homebrew_PCBs@yahoogroups.com, "don2822003" <vk3yv@...> wrote:
>
> Hi all, Sodium Carbonate is sold quite cheaply as a swimming pool
> additive to raise pH in swimming pool water, also known as Soda Ash.
> The mixture I use is 7 grams to a liter of water. I use it with Riston
> sensitised  board which looks to be the same type of sensitising that
> has been discussed on this forum lately.
> Don VK3YV....
===================================================

> Lots of people wrote:
>
> ...ABOUT SODIUM CARBONATE

Does this dry film resist people are
playing with not develop under sodium
silicate?

The pre-sensitised boards I use prefer
sodium silicate over other developing
chemicals.

Andrew wrote:
> 
> 
>  > Lots of people wrote:
>  >
>  > ...ABOUT SODIUM CARBONATE
> 
> Does this dry film resist people are
> playing with not develop under sodium
> silicate?
Correct.
> 
> The pre-sensitised boards I use prefer
> sodium silicate over other developing
> chemicals.

Is that a 'positive' (exposed areas wash away in developer) resit ?

The negative dry film resist must be developed in Na2CO3 and should be 
%0.9 to %1.1 concentration, at 25 to 35 deg C. Interesting, high 
concentrations (>%10) actually slow down the development process.
The very high pH of sodium silicate will strip negative film right off 
the board. You use NaOH at %1~%10 to strip it off board.

D wrote:
> 
> 
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "don2822003" <vk3yv@...> wrote:
>  >
>  > Hi all, Sodium Carbonate is sold quite cheaply as a swimming pool
>  > additive to raise pH in swimming pool water, also known as Soda Ash.
>  > The mixture I use is 7 grams to a liter of water. I use it with Riston
>  > sensitised board which looks to be the same type of sensitising that
>  > has been discussed on this forum lately.
>  > Don VK3YV....
> 
> It's even easier to get than that. Just go to the grocery and buy
> a box of "washing soda" (usually produced by Arm & Hammer here) [1].
> Also, there's a way you can produce it from baking soda by baking
> it.

Alternatively, take some sodium bicarbonate from your kitchen pantry, 
place in a dry cooking pot and heat on the stove >200 deg C, to get your 
sodium carbonate anhydrous (i.e. Na2CO3 without the water molecule it 
likes to bond too).