If it is a certain look that you are trying to achieve ,it is going to very much depend on the bricks and the way they are laid up. Repointing is almost the same thing as you are proposing to do , if the joints were deeply raked out when the mason built it then you stand a good chance of a successful repoint without much prep ,but if the joints are a simple concave then it will be necessary to grind them out with a tuckpointing blade and clean with compressed air and then dampen the work area, bag and tool the joints in let them set thumb print hard then kept damp for a short time after while the new joints set up. If done properly ( and the facing is in good structural condition ) then a sealer should not be needed unless it's sole purpose is to change the color in some way. An application of mortar over the face of brick is likely just to smear in a way you may not want, test first.
Brickman

Thanks so much, brickman! The joints on my fireplace surround are simply concave, as you describe, so I guess this is going to be more work than I anticipated. I was hoping to avoid a full-blown repointing, as it would be a very big job -- the fireplace is floor to ceiling and an L-shape with a raised hearth. I do want to avoid painting, so I was hoping that sanded grout might be a better option. Oh well. :-(

AM I am doing the same thing and will be using the brick and mortar stain from Dyebrick. You can check them out in the link below. If you look at the customer galleries you will see some examples of people who have done the same thing.

Here is a link that might be useful: Dyebrick

nhyankee:

This looks very intriguing -- but seems to be a product only available in the uk? Do you know if it is available in the U.S.? I've done a preliminary google search, but didn't find anything.

Thanks!

AM it's only available from the UK as far as I know. But some of the gallery participants are in the US. It's not the cheapest stuff but very long lasting and really the choice for what I want. I have been waiting for a sample. There are some other things which you could look at such as Keim paint or silicate mineral paint which is a compound that makes a petrified layer on the brick not unlike what Dyebrick does. It's not like a paint that scrapes off so it is good for standing up to the heat of fireplace areas.

I'm not sure if I am going to be dyeing the mortar but with a careful hand you can use that product and get an almost new look. Make you look at the videos on the Dyebrick site, they show quite a bit.

There are a few distributors of mineral paint in the US. One is Sydney Harbour which is a US distributor of Porter's Paints from Australia. Another is Eco-house out of Canada. I hope that is helpful.