Painting - paint left on tools

I am using latex paint and need to run out to the hardware store for more paint. How long can I leave my brushes etc with paint on them or should I wash everything before going to the store?

I always clean my brushes but you can wrap them in tin foil and they should be fine for an hour or so.

Its usual practice for pro`s in the UK to leave oil based paints in water (bristles only) They`ll be fine so long as the water does`nt evaporate!! We don`t use latex paints so i cannot comment but all other waterbased paint brushes & rollers are left in plastic bags,which keeps them wet for....years even!! I have a roller which is used only for ceilings in white emulsion...I have`nt washed it for over 5 years!!

When we go to lunch I will leave my brush in my work pot with about 2 1/2 inches of paint in it covered with a damp rag. Rollers will last over lunch dipped down in the paint and then hung on the inside of the bucket with a damp rag placed on top. We always use 5 gallon buckets to roll out of.

When we go home for the day we clean everything thoroughly. Those are my rules for everything that belongs to me. I will however on occation leave my exterior brushes overnight as mentioned above :) , but is not good on them as it can bend the bristles, it depends on how tired I am.