I’m no expert but we did redo our fireplace and I did a little research on various approaches. Here are some ideas to change the mortar to start you out. You will have to research in detail with a pro (although the brick and stone masons we talked to were not very experienced with being creative problem solvers). And go to your local brick yard and ask more questions.

1) If you want to Try to lighten it you could make a solution of muriatic acid and water and apply it to the mortar and then rinse it off in a few minutes and see if it lightened it. You will want to wait a day or two for it to dry to check the color. Do a sample first. We passed on this idea Since I didn’t think it would lighten ours enough and it seemed a lot of work.

2) Go to a full service brickyard to checkout the mortar dye colors available. There is a fairly wide range of dye at the brick yard—Home Depot just has a few dye colors—Amazon has a few more. Mix up a small batch of mortar with some drops of dye to see if the resultant color might work. You will have to make a sample, spread it on a hidden area and let it dry to get the effect. This will require chipping out a half inch or so layer of the the old mortar to apply the new. I would check with an expert on how to proceed—my info is from the internet and we didn’t use this method. We bought the lightest mortar available to try and it was not very light after drying. We did not try to make orange or brown or any colored mortar from dye.

3) We ended up just filling the crevices between our stones not with ‘mortar’ but with ‘grout’ (‘standard white’ color) and then gave our stones a wash of diluted grout to lighten those as well. We had more space between the stones to fill with grout than you appear to have. It took about six hours to do the actual work. It took us a few days to research, buy sample products, try them and let them dry so we could check them out.

4) Paint the mortar and avoid painting the stone. But I thought that would look weird for our project. Or default to the German Schmear technique and it‘s various versions but that would entail adding a wash of some kind over your stone as well.

The lady at our brick yard had some good ideas and advice for us but nothing was clear cut. We had to experiment. Good luck.

Take a picture from further back to show the whole FP/

I would love to get an opinion. I found this masonry paint and did a test in a hidden spot. What do you think? paint all of the mortar or leave dark? Thanks!

There was an article/posting on here lately about putting more grout in between the stones,

if that is an option. You could then use a different color.

J Inhof, would you mind posting a pic of your fireplace? Thanks so much!

We cleaned the stone with a stone cleaner from our local fireplace store. Then painted the grout a lighter color.

I recently painted the grout in a stone fireplace using Flexrock by Beauti-tone. It is a stone coating... you can see here the previous dark brown mortar that someone had painted on and parts of the new grey. Up close it looks just like mortar. Super easy to do...this took a couple of days - just tedious work. Their website is www.techstone.ca . They have several colours. I realize this is not the prettiest fireplace but it worked for the situation. I also used this to cover up the front sidewalks that were stained red.

I see the after,, it's beautiful.

What a difference changing the mortar has made in all of these pictures! I’ve researched multiple ways to lighten the look of the FP.......whitewashing, limewashing, various schmears, overgrouting, covering with drywall, etc. I really think the stone itself is pretty so I’m reluctant to make changes that are permanent. Changing the mortar color to a medium gray seems to be the best option for me but I’ve been told that if I use a color that is too light, the FP will look like a giraffe......not a comforting thought.

Momma Farmer, what color did you use?

j inhof, do you know the ratio of water to grout for the wash you put on the stone? I just love the overall lighter look!

Well done...I am such a fan of this whitewashed stone look.

Now you just need to finish off the opening with a new door or screen.

Black Rock fireplace doors in Natural Iron

Custom Solid Brass Screen and Andirons in a Pewter Finish

Provided by: Hansen Wholesale

joan head curious what you ended up doing? Also wondering about the mortar paint product you found and what brand it was