Drilling into brick wall and hitting something hard?

[footprints]

Could well be bricks with black patches in them they can smell odd, only way you will find out is chip out some of the wall messy, but at least you will know if it happens elsewhere. Gas pipe or conduit still a possible cause.

 

[whatnot76]

Could well be bricks with black patches in them they can smell odd, only way you will find out is chip out some of the wall messy, but at least you will know if it happens elsewhere. Gas pipe or conduit still a possible cause.

Thanks. Would black brick be particularly hard to drill through?

 

[tony1851]

Victorian common bricks often have bits of hard stone in them as the clay-sieving and grinding machines were often not that efficient and the bricks were very variable in quality. You've probably hit a hard fragment, plus your drill bits are worn.
Drill small pilot holes first (3mm or 4mm) and work up in size. Drilling a small pilot hole enables greater pressure on the bit, but keep withdrawing it as otherwise it gets too hot.

 

[whatnot76]

Thanks all for your comments. The mystery has been solved. Just thought I'd write about it in case anybody else comes across the same issue, because I suspect it might be a common occurrence in terraced houses.
Our neighbour had a look at the wall. He's done a lot of work on his house so he understands how these houses were built. Turns out it was very hard black brick that they used to build the chimney breast. He seemed pretty confident of this so I let him finish drilling the hole. We used the same drill but with his JCB carbide tip drill bits (as mine had melted!). He's stronger than me and just went hell for leather for about 1 min and managed to drill a hole about 10cm deep. I noticed at first there was grey dust coming out, and then red dust.
Anyway, hopefully this is interesting/useful to anyone out there undertaking a similar project on an older property.