Originally Posted by ISTFlyer

There is no baggage storage facility at Istanbul Airport, you could either check your bags all the way as your connection is technically less than 24 hours. However, if you want to store your carry on, you could store them at the lockers at the lounge, if you're planning to re-enter the lounge for the second time. Yes, you could head to the Business Lounge just after arrival but be aware that you should clear transfer security first as SIN is not a clear destination, you must also have your BP for your CDG flight present at that time. If the SQ agent in SIN won't be able to issue, you need to first proceed to the transfer desk. Of course, you may leave the lounge and the airport but it won't be easy as SIN or CDG T1 as in IST, airside and landside does not use the same path. There should be a way out from the international airside to the baggage claim but unfortunately no one knows how. You could access the lounge within all the 24 hour period before your flight so that means that there would be no problem accessing the lounge at midnight.