Originally Posted by SweatySock
Also, can you 'over-cure'? If you leave a piece of meat too long in the curing process does it get saltier or tougher?
Sorry - missed the second part of your question.
Again there is no simple answer to this as it will depend on what type of cure you are using. You can cure by adding salt/sugar, by increasing acidity, by removing water, by adding nitrite/nitrate or a combination of all of these.
When dry curing using salt (e.g. fish) it is very easy to over cure and the result becoming too salty. When removing water (e.g. Salami), when over drying the texture becomes dry, the surface hard and it is unpleasant to eat. If using too much Nitrite then over curing can make the end result toxic.
To avoid any of the above, the important thing is to do a lot of research before you try a curing method that you have never used before and follow the advice and steps taken by someone with experience. Once you are comfortable with the principles of that particular cure method then you can tweak the method slightly to make it your own.
If you are not using Nitrite then over curing using the other methods will mostly just result in something inedible, but when using nitrite it is important to use a method that does not actually allow you to over cure. This involves accurately weighing the meat that is being cured and only adding sufficient Nitrite so that if all of it is taken up it does not exceed the maximum safe limits. When dry curing this is a very straightforward calculation and when immersion brining there are a few more factors to take into consideration. There are a couple of very good cure calculators online that make the calculations very easy. The first time you try curing just post up your proposed method in the main forum and very quickly someone will verify it for you. Once you have got the cure calculations nailed then, within reason, it is hard to over cure with something like bacon - much easier to over cure though with fish.