Is this for a patio outside or a brick floor inside? You use morter . It can come in tubes like caulk. Just fill in til it full. smooth out with a putty knife or trowel.
It’s for the face of a fireplace. I want to fill in the Mortar joints and have a smooth surface.
Here is some very detailed information that might help you. The article explains about mortar - the ways to mix it, the preparation and the actual applying of the mortar. It's not a short article, but there is a lot of information there. I hope it helps you. Wishing you the best.
Yes, mortar. It’s a ton of work & messy.
If you want to tile the face of the FP, use a little bit bigger tile and span the mortar joints and then you don’t have to fill them.
If you don’t have a plunger you can put half a cup of baking soda and a add a cup of vinegar to unclog your toilet.