We have laid a black & White chequered porcelain tile floor, the tiles are HITOM (Chinese, but purchased from a local quality tile supplier). The tiles were cleaned with "Wax off" and then sealed twice with FILA MP/90 Prior to grouting. A black grout was used but this "stained" the white tiles. We have tried a number of different chemicals and steam cleaner to clean them but grey steak marks remain.
So then the floor was pulled up and another set of HITOM tiles (from B&Q this time) were used but this time with a neutral grey grout. The tiles were cleaned with Wax off and then given 2 coats of Aqua Mix Ultra Solv. After grouting the black tiles were left with light coloured staining (although not as bad as the first lot of tiles). With a lot of effort (using nano scrub) this has been reduced to almost acceptable.
I have searched the web and found that porcelain porosity can be an issue but this should have been resolved by the sealers. I have a theory that the "pores" on the polished tiles are too large and granules of grout gets lodged in them, rather than the grout stain.
Has anyone seen the same issue?, Know why it is happening? has a solution?
Thanks.

You could try this product from BAL ...specifically designed for use with pigmented grouts.....then clean it off and then use the porcelain sealer........but ring BAL tech line first to check for suitability....

BAL Protective Sealer
A water-based polymer emulsion specifically formulated to provide a temporary, protective coating to ceramic tile/mosaic surfaces during the grouting process. Suitable for use with all BAL grouting products.

BAL PROTECTIVE SEALER is a water dispersible temporary sealer designed to protect the tile surface against discolouration which may arise when using pigmented grouts. It is not a permanent sealer.

I am surprised! If I am reading your post correctly where exactly was the staining/Streaking? Just around the edges or all over? If Nanoscrub virtually eliminated it the second time why wasn't it tried the first time? Did you seal with Ultrasolve prior to fixing or after fixing or both?

I know question and questions but if you can clarify a little further I may be able to help.

Kev

The staining was all over, but streaky. I did an experiment on a black cleaned tile and then put 2 coats of MP sealant (leaving to dry etc.) and then just dusted some neutral grout powder over the top and blew it away.
The dry grout has stained the tiles. On the first batch of Hitom tiles I could not remove the stain even with a jet washer, but the 2nd batch were better but still left a very faint haze.
I suspect that these tiles from Hitom use a larger grain size (rather than the fine grain size of the expensive Italian tiles) and when the tile is compressed, fired and then polished the resultant pore holes trap the particles of grout. So I think it is not the stain coming from the grout but the grout particles are are held by the tile surface.
I think this is a process quality problem with the tiles and perhaps the only solution is to mask off the tiles when grouting (a real pain) or perhaps Dave's suggestion of the temp sealer may work.

A temporary sealer may help in this case providing you can get it to adhere. This is usually quite difficult because of the surface tension. I can now understand how the Nanoscrub got at it if you allowed the dwell time but you could try using Grout Haze Clean Up backed up with Nanoscrub.

Kev