What acid actually does is ‘eat’ (corrode) away your grout ( tile line) so it gets thinner and thinner. And over time your whole grout...

For sealant , It is advisable to clean grout before using these products as old fungus and dirt will be still affect your grout if not...

In a nutshell: Acyrlic/epoxy = Actual grout Grout seal/pen/tube = Grout accessories There are many kind of sealant in the market, like...