I was told that part of the problem on a new glass bottle of ketchup is the surface tension at the top. So if you break the top layer with a knife or whatever t

I was told that part of the problem on a new glass bottle of ketchup is the surface tension at the top. So if you break the top layer with a knife or whatever the ketchup will suddenly start coming out. However I never looked up if it was true or not (surface tension) but it does appear to work albeit slightly unhygienic.