Once you figure it out, maybe you can assume that the different batches with the same label are close enough. Luckily, the amount of carbonate in a developer, for example, does not affect pH that much; it's more about buffering capacity.
you can convert baking soda to washing soda if you run into a problem
just put it on a cookie sheet and then in an oven low heat for a few hours
the heat will force the moisture out and convert it to sodium carbonate.
Last edited by jnanian; 06-26-2012 at 01:13 AM. Click to view previous post history.
Reason: whoops, thanks professor!
I believe you mean baking soda and not baking power. Baking power contains both an alkaline component (typically sodium bicarbonate, also known as baking soda), one or more acid salts(like Tartaric Acid), and an inert starch (cornstarch in most cases, though potato starch may also be used).
Baking soda is just sodium bicarbonate without all the extras.
In the UK ,widely available Dri-Pak Soda Crystals are labelled as containing greater than 30% sodium carbonate decahydrate.I phoned them up and spoke to a technical guy from the factory who told me the crystals in fact contain 99% decahydrate.There is now some anomaly in the packing regulations that causes >30% to be written on the packs (sounds like the EU again).I have not actually done the heating test to confirm this.
This is surprising considering the cost of shipping. It is rather inefficient to ship the decahydrate as you are paying to ship a lot of water.
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Most hardware stores and most Walmarts have swimming pool chemicals. A common pool chemical known as PH Plus is sodium carbonate, same as the hard-to-get washing soda. It may be the mono-hydrate. I use it to make my developers that use sodium carbonate.
Happiness is a load of bulk chemicals, a handful of recipes, a brick of film and a box of paper. - desertrat