There were few times Dad interfered with me growing up regarding safety. One such time was when I commenced to add refrigerant to a old Olds Cutlass that I owned. I was going to use one of those can with hose kits popular back in the early '70s. Dad stopped me and asked what my life was worth to me, and admonished that I should go get a set of gauges from the parts store so I could monitor pressure (especially low side) so the can would not explode in the event of system malfunction.
I listened and bought the gauge set. It was about 20 dollars or so, the equivalent of about 200 dollars today. There turned out that the A/C system was fine and the repair went uneventfully. I wore goggles, too, at Dad's behest.
I still have that gauge set in a box somewhere. R12 is no longer used, but there is such a thing as posterity!