Homebrew PCBs

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....
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