The Battle with Ketchup

How to use a ketchup cup. The right way! 

What a revelation!

That post made me think about tactics to get ketchup out of a traditional glass bottle. I always seem to struggle with the process and end up with ketchup splattered on my clothes or three times as much on my food than I had hoped for. Using a knife to guide the ketchup out doesn't do the trick and pounding on the bottom just causes a huge puddle. It's a mystery to me.

Can someone share the secret trick?