Down here in the south, duct tape is popular
If I remember right, the water glass was mixed with another ingredient that it reacts with for the muffler repair putty.
If the threads are well made they shouldn't really need sealer for low pressure exhaust. Modern pipe threads were once referred to as "dry seal" threads. While high pressure gas and liquid applications need sealant, this is mostly done to help assembly (lubricate) as well as to "insure" a good seal.