Saturday's goalless draw with Blackpool was the Addicks' first league shut-out of the season, and a first at The Valley since November 2012.
"It's a relief to be honest with you," admitted Hamer.
"We've been waiting for one all season and it's been well documented that we haven't kept a clean sheet for a while - so obviously it's been on my mind.
"You can be terrible and keep a clean sheet and you can also be on fire and lose 3-0.
"So it's swings and roundabouts really but obviously clean sheets are what me and other goalkeepers pride ourselves upon, and there haven't been too many this season which is disappointing because we should be keeping a lot more."