Cake – repair a cake tin which has started to leak

Don't most cake recipes require mixing dry ingredients first? Well, what's been done has been done.

The standard professional chef way of getting lumps out of anything is to pass it through a fine strainer. In your case a standard metal pasta strainer should work. Put the strainer over a bowl, pour the batter in and use the back of a large spoon or ladle to gentle press the batter through. The lumps of sugar will be left over and you can just crush them then.

Whipping the batter might work the gluten proteins in the flour which will make for a tough chewy texture. Some cakes actually take this into account and others it is bad, so be careful.

It's possible that your new brand of self raising flower has more raising agent. This causes a initial raise to happen faster resulting in large 'bubbles' that are less stable. The cake rises higher and then is more prone to falls.

Fast changes in temperature or air pressure will cause the cake to collapse. That means every time you open the oven, or if your oven isn't very air tight every time you open an close the kitchen door. Loud slams of doors are especially bad.

Higher levels of raising agent are especially an issue if you live at a higher elevation or if there is low air pressure that day.