It's an interesting home chemistry demo project to make sodium carbonate from baking soda -- sodium bicarbonate.
Get that box of Arm and Hammer out of the refrigerator and dump into a heavy saucepan. Heat to 400 degrees over a moderate heat, stirring occasionally.
After a while the powder will start boiling. Yes, boiling. It looks cool and will impress your kids.
This is the CO2 dissociating from the bicarbonate. Eventually, all that is left is sodium carbonate, a fire-resistant powder. The CO2? That's how dry powder fire extinguishers do their trick. The bicarbonate absorbs heat and releases CO2.
It's also how soda crackers get fluffy.
Or you can just be boring and buy laundry soda ...
Incidentally, sodium carbonate is sometimes used as a yellow colorant in fireworks.
73
Jim N6OTQ
>________________________________
> From: James <bitsyboffin@...>
>To: Homebrew_PCBs@yahoogroups.com
>Sent: Sunday, July 7, 2013 8:17 AM
>Subject: Re: [Homebrew_PCBs] Developing dry film photoresist
>
>
>On 08/07/13 01:06, Duane C. Johnson wrote:
>>
>>
>> I agree, the bath must be alkaline and a common
>> and convenient alkaline bath is "Sodium Hydroxide".
>> I get mine at the local hardware store where
>> plumbers use it as a drain cleaner.
>>
>
>Drain cleaner, soap manufacturing, methamphetamine production and
>melting the flesh of your enemies... all popular uses for sodium
>hydroxide (lye).
>
>Sodium carbonate is way way safer, and works just as well (the
>"developer" that some ebay sellers include with their dry film, it's
>just sodium carbonate). It's found in a large variety of household
>products in the laundry aisle of your local supermarket, look for
>natural fabric softeners and laundry powders.
>
>Takes a little longer, but you don't have to worry about chemical burns,
>or having (more) hazardous chemicals around the place, and much less
>chance of leaving it too long and stripping the resist when you were
>just trying to develop it.
>
>
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