you don’t describe why they don’t look great (stains, dirty, dull, patchy etc) so it is a little hard to advise. By ‘nano porcelain’ I am assuming a polished porcelain that is presealed with a ‘nano’ sealer. This does not mean much, only that the tiles are sealed with a thin sealer that could penetrate the tiny micropores of the tile.

We have seen plenty of this type of factory presealed porcelain that has a kind of coating on them (not transit wax, but sealer residue) and it can be pretty difficult or even impossible to remove. you could try an abrasive cleaner like Microscrub, or a solvent (like a stripper). Do yo have any photos?

Hope this helps

Ian

In the ‘early days’ of porcelain it was most likely true to say that porcelain did not require sealing but since then:
Production has spread all over the world
Competition has increased
Quality has slipped
More and more porcelain, of various qualities is supplied ‘polished’
Polishing can open up micro pores that hold grout/dirt and other contaminants
in an attempt to get over this, some (but by no means most) factories are now coating their porcelain with wax or new so-called nanosealers at the factory

The problem is not all these sealers prevent staining and some create issues of their own. So these days it is not possible to state categorically that ‘porcelain needs to be sealed’ or ‘porcelain does not need to be sealed’ – in reality it depends on the particular porcelain.

So ask the supplier of the particular porcelain you are considering buying for their manufacturers recommendations, get them to show you this in writing if they can, better still get a sample, take it home and try to stain it with red wine, a marker pen etc. See also if it feels waxy, use an alkaline detergent to clean a section and see if it is different as a result (showing that you have removed some wax).

This way yo can determine if you need to seal it, and if you first need to strip it

hope that helps

Ian