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 cleared.
After completion, do remember sealant is not acid/bleaach resistance so do take note of your cleaning agent.
It is also not scratch/peel resistance so it is not recommended to scrub your floor.
For grouting, it is advisable to remove your old grouting. Becareful with your strenght and angle when using grout removal tools/machine as it can easily crack your tiles at the side.
After applying, no note the curing time for each manafacture brand and which grout you start with as prolong might leave residue at the side of tile which is hard to remove. If you happen to come across, do use a debond agent to gently rub off the residue.
After you have completed your new grout, do remember its after care and if it is able to be in contact with acid or bleach for your cleaning agent.
If you are encountering problems with completing, we do offer our services for you.
Just take a photo and adequately share your issue with us.