Fire clay

[david s]

Here in Australia bricklayers sometimes add what they call fireclay to their mortar to give it a stickier consistency. Be careful, at bricklayers suppliers it might be labelled fireclay, but it isn't, the stuff is not particularly refractory and because of this confusion it is now being labelled as bricklayers clay. Best to source fireclay from a refractory supplier or a pottery supplier.