porcelain

You need a diamond coated core bit, if its just a one off job then the cheap ones from hong kong will do fine, if you are doing it on a daily basis then the Rubi or Armeg kits may be better.

If you can wait 4-5 days for delivery then Richon are cheap, the 12pc set is good value.

Or if you prefer buying from the UK look through the posts in the last week for 356 drill's site.

Jason

 

If it's a vertical surface just keep dipping the bit in a water to keep it cool. If it's a horizontal surface you can pour water into the hole as you drill it.

BB

 

I just trickle a bit or warer from a sponge or use a garden sprayer.

For Safety you should use a cordless drill if you are cooling with water and keep the speed low. Have a look at 356drill's site for how to use the bits especially getting them started.

Jason

 

On the wall tiles I tend to have my mate hold a sponge under the hole to be drilled and have a garden sprayer spraying a continuous tiny jet at the hole.

The best type of sprayers are the ones that you can pressurize and that have a permanent on button.