When to use selfraising flour and when plain with soda etc?

[Colourworld]

Generally I know when to use these two different flours. I have just baked nice chocolate muffins using self raising flour but I know that the plain flour plus bakind powder and soda could be used instead of the self raising. I, however, do not know what to add to the plain flour to make it self raising. I have read recipes where two tea spoons of bicarbonate of soda added, plus baking powder, tartar cream. Is baking powder not similar to soda? So, when I am perfectly fine with my self raising flour for baking muffins when do I actually need to use plain flour plus other ingredients or it does not matter?

One more question, I remember my mum was adding to the flour just bicarbonate of soda. Is this one ingredient not enought to make the muffin dough or do I have to add other ingredients like baking powder and which difference would they make. Sorry for tedious questions.

i part bicarb plus 2 parts cream of tartar makes a simple baking powder. Recipes with SR flour, for example, for muffins, cookies, etc sometimes still include bicarb. It adds something - would have to google to be more specific though!

Sometimes it's given as 1 part bicarb, 2 parts cream of tartar and 1 part cornflour. Use 3tsp for each half pound/225g of flour to make self-raising.

If, for example, you make a choc cake with melted chocolate you need to increase it to 4tsp because the mixture is heavier. On the back of the tubs (except Tesco) is a list of the quantities you need to add to half a pound of flour for cakes, fruit cakes, scones etc

that's interesting tb

What I really do not understand why there is a need to add bicarb to self raising flour. I have read somewhere that consuming too much soda is not that good especially for those suffering with high blood pressure.

It just seems to be for some things, maybe if they have something acidic, like scones with sour milk iyswim. I make drop scones and they need both bicarb and baking powder. Does wiki have any suggestions?