So we're getting close to the point of Tiling over our brick fireplace. Yesterday we applied some mortar to a few of the crevices (not the old grout joints) and the NEWLY-applied mortar was a bit sandy and flakey in spots.
Someone told us: "Mortar is not meant to be used as a skim coat. I suspect, too much sand in the areas that flaked. Brush off with a wire brush any loose mortar. Apply a cement based patching/embossing filling compound and smooth for your tile install. You might have to apply several coats to achieve desired smoothness. Speedfinish is one such compound:
SpeedFinish 10 lb. Patching and Finishing Compound-SF10 at The Home Depot
So my question is more of what do you think of that opinion? We should NOT use basic mortar compound to fill in the grout lines? We'll be using a Thinset with a Latex Adhesive as the base for our Tiles.
so confused... Thanks in advance.