Pin holes in new grout

Anyone have any experience/answers to why we are getting small pin holes in parts of the grouting as it dries? Are renovating the bathroom currently but also had the same problem with kitchen earlier in the year. Never had this problem before - looks like we will have to re-do with a top coat. Using Wickes Waterproof Tile and Grout.
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What are you mixing the grout with ? If your beating to much air into it, it will act like pancake mix and bubble up all over the place. Or it could just be the stuff Wickes sell.
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With powder based grouts that you add water to it is because you are making the mix too wet. Mix it stiffer and you will never get pin holes.
David www.tradetiler.com
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stuff we used earlier in the year was from Focus and did the same. Must be us - using fairly wet cloth to get off excess then using finger to get the finish on the line of grout and then just a damp cloth to get the last small lines off tiles. Have tried drier cloths to no avail. Thanks for the replies.
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If it helps, that's basically the same technique I use, but with B&Q grout and wring the cloth out before use. No pinholes.
Andrew
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Aiden wrote:

Tile & Grout? Are you leaving the cement to dry before grouting? Is the depth of the grout very deep? You can get problems with shrinkage as the grout dries - is the surface being pulled down in a "v" section trench after you sponge off, are you getting holes at the intersections, or holes from bubbles in the grout, or what?
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On Fri, 17 Oct 2003 12:18:01 GMT, "jerrybuilt"

Yep, cement/adhesive dried a good couple of days and yep, too, the grout is quite deep in places - but, strangely, there are more holes in the verticals than on the horizontals - and, nope, no V section - and the holes are actually from bubbles in the grout.
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On Fri, 17 Oct 2003 12:18:01 GMT, "jerrybuilt"

Correction - re: previous reply - as you say there is a "V" section in the grouting where the holes have appeared but not in the areas where there aren't any holes. Why is this "jerrybuilt"? Obviously for future refence. Will it be OK to run a finger of grout over the "holey" area or will her-indoors have to dig out all the problem areas and start again :-} ?
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Aiden wrote:

Apologies for the late reply. It seems to me that when an area is spread with adhesive, using a notched trowel or half-moon, it is possible to leave a void under the edge of the tile. If, for instance, you comb vertically, and the "furrow" in the adhesive co-incides with the intersection of two holes, there may be a deeper trough between the positioned tiles. The adhesive will "go off", and when you come to apply grout, it will fill the gap between the tiles (or extra-deep for whatever reason trough). The tile won't absorm moisture from the grout, but the grout and substrate are likely to, so "suction" dries out the grout from the bottom towards the surface, and as the grout dries it shrinks, leaving a "V" and possibly pin-holing as the disturbance through shrinkage affects any air bubbles. Sounds good, anyway!

If it's clean, I don't see why not. It might be an idea to damp down (not excessively!) before grouting, too, but I've never tried it.
I tend to treat the surface if absorbent, apply grout, comb, press on tiles firmly (*beware* cheap "picture" tiles craze *very* easily) using spacers stuck in point first along the joins, not pressed betewwn the intersections, this means you use more spacers BUT control is far better and you don't lose spacers behind the tiles which can lead to problems), remove any excess grout squeezed from between tiles using a damp sponge, remove grout from the finish-for-the-day end of tiling area with a scraper, let grout dry overnight, remove spacers, squeegee in grout, and then using a *new* FLAT almost-dry fine textured sponge, gently wipe off surface grout with sweeping movements of the sponge (washing and wringing the sponge as dry as possible when needed). The movement of the sponge "drags" out the grout lines to the correct profile. Don't press hard" The tiles should look clean when this has been done, but will dry with a dusty, foggy look, which can be polished off with a clean fine cotton rag to finish. Very quick. Very good results. No sore fingers! Practice!
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