Gas tank sealer

[Terence Mcgaughey]

Does anyone know the trade name & the manufacturers name of the sealant that is put into gas tanks to seal up the rust and fill the pin holes caused by old gasoline ?
I'm looking for the self application method as
the local commercial place that used to do this stopped as most people just bought a new tank for their car .Rather difficult to do with two gas tanks for a sixty year old carrier .
Thanks in advance .