Re: What is in soap scum?

One of the characteristics of the molecules which comprise soap is a free 
end which is particularly attractive to fat molecules. Soap scum is just a 
combination of the two. In order to remove soap scum, most cleaners contain 
two elements: an alkaline compound (usually sodium hydroxide or a related 
compound) and a mild abrasive. Since sodium hydroxide is fairly hard on the 
skin, that is why most bathtub/sink cleaning agents recommend you wear 
rubber gloves when you use them. Ammonia is also an effective scum remover, 
because it is capable of dissolving fat, which comprises the bulk of soap 
scum, but again, it's very hard on your skin and you ought to use gloves 
wyhen you clean with it. (If you use lots and lots of soap, you won't find 
soap scum - the reason it appears is because people use enough soap to 
remove fat from their bodies/dishes, but not enough to actually react with 
all the fat. So a lot of fat is set free, but has nowhere to go but the 
sides of the sink!)