sealing black porcelain before black grout

[jonnyc]

Just finished laying 230 sq mts 1000 x 1000mm black porcelain mat finish tiles and client has specified mapei black ultra colour grout.
tiles do not seem porous at all as they take at least 30 mins to dry off after cleaning.
I have a few worries:
1. even after washing tiles 3 times there are still dust/ wipe marks on tiles. this leads me to believe that they will be very hard to keep clean.
2. I can recommend a lithifin maintainer or similar but is there any advanatge in sealing tiles beforehand which might make them easier to maintain.
3. other worry is that using a very dark coloured grout to try and match black tiles, will the colourant stain the tiles if not sealed. I have had problems 20 odd years ago with using colour pigments but maybe these new grouts dont stain as they used to.
4. i am a stone fixer primarily and also clean and reseal stone on a regular basis so understand the care needed in sealing hard limestones so that they do not streak but with porcelain it is a new issue for me. If tiles need sealing cost is not a factor but am very worried about streaking on an unporous tile.

Any input from fellow tilers would be much appreciated.
I have read a few threads and this seems to be vary grey area.
As stone fixer I would always seal stone but it semms a bit of joke that when porcelain manufacturers who were copying limestone tiles at considerable expense but with very good results,their mainselling point was that you did not have the worry of sealing tiles as with stone.
Now they seem to say maybe porcelain might need sealing to cover their backs.

[david campbell]

there isn't really any need to seal these tiles but try rubbing them with a dry t-towel to wipe of the excess dust once they have dried

[Tilestiles]

Personally I would seal the tiles. Especially if using black grout

[jay]

hi you may need to use an ipregnator (sealer ) doesnt affect the finish

[faithhealer]

hi you may need to use an ipregnator (sealer ) doesnt affect the finish

Yup did this on an offcut yesterday to prove to the customer, can't tell until you run it under water

[heavytrevy]

I just finished a job with 600 black porcies, I sealed them twice with impregnator type sealer and they came up great.

Trev

[garythetiler]

try using 2 coats of the bal temporary sealer it will give you enough protection to get your grouting done

[pjc]

use black grout on porcelain all the time never sealed it yet