2) Having had some wall gaps filled with the expanding foam stuff, I want to cover it over with a mastic type material to weatherproof it, once its cured. In B&Q I found something called caulk in the tubes you use one of those guns to dispense with (like the silicone bath-edge stuff). Is this what I should be using? SWMBO was asking why I wasn't using the silicone stuff anyway (she likes me to use stuff we have in stock).
Thanks.
I run mine at the same speed I'd run a regular multi-material bit, i.e middle of 3 speeds on my cordless. The trick with these spear-point drills is to push them against the tile so you hear a tiny crack as it pierces the surface glaze, before starting to drill, otherwise it just skitters over the surface. If I've a deep hole to drill in masonry behind the tile I change to a proper drill, but the spear-point will go through plasterboard OK.
OK ta.
You can basically never have a drill running too slow in practice - only too fast. It's heat that kills them and this is a product of pressure and speed. High pressure low speed is far better.
You're probably thinking decorator's caulk? This is for filling gaps in plaster etc and isn't IIRC waterproof. It can be painted over. Silicone can't.
Slow. If the tile is really hard (e.g. porcelain rather than pottery) you will need water cooling as well. Once through the tile, then use a normal masonry drill if the wall is hard behind it.
Much depends on where these cracks are, and how big.
Caulk is for internal filling only really - its a flexible filler for decorators to use on small cracks and gaps. It shrinks a bit and never sets particularly hard, although its not as flexible as silicone. You can paint it.
I found they drill best by just running the drill top speed and getting right on with it, no need to pre-crack glaze, and had no problems at all doing it that way. I did apply masking tape and drill through it. Yes, you do need to change bits once thru the tile, spear head bits dont like masonry, and masonry bits dont like ceramic tiles.
Thats quite different to what people usually advise though, make what you will of that.
NT
Not in fact cracks but unfilled gaps around waste-water and soil pipes exiting the house through the wall. Filled initially with the expanding foam, but I've been advised that it should be weatherproofed.
And daylight affects expanding foam so should be protected by some other coating .
Hence why I'm looking for mastic or whatever the black stuff is that was applied around some of the soil pipes of this house we just moved into. Some had it some didn't.
Cheers,
I start the hole with the bit in a wheelbrace and 'rock' the bit - holding the wheel, not the handle - and that avoids the bit 'walking. I can also hear what the bit's doing, as the 'motor' isn't very loud.
Once, just out of interest, I started the hole (6mm) by holding the bit and carried on as it seemed quite easy. Took about a minute to get the bit through an ordinary tile, twirling the bit back and forth.
For a small gap (say less than 15mm) I would go for a silicone frame sealant in an appropriate colour (can't be overpainted). If its bigger than that, then sand and cement mortar first, and silicone as a final seal once that has gone off.
I think it reflects that there is a wide range of tile compositions available. What works best depends quite a bit on the tile in question.
Softish pottery tiles are pretty easy to drill with anything in my experience. Really hard ones are difficult to drill with the right tools and technique and near on impossible any other way.
Yes - I got nowhere with tile drills on my porcelain ones. Had to get a diamond cup type one which had to be kept wet.
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