Finishes for facing cobblestone and mortar

My mason is recommending a masonry/grout sealer for the rocks and mortar we built as the facing for our FireSpeaking masonry stove. I’m wondering about the fact that the stove, rocks and mortar will get hot while using the stove and how that will effect the sealer? Any recommendations?


Hi @dclaire! We have never used a sealer on our stone-faced heaters for the same reason you are concerned about it. I am curious what @SolidRock has to say about it since he is both a very experienced stone and heater mason!

Can’t wait to see pictures of your stove!

I have used Sonneborne Cure n Seal 25 LV for the past 18 years on stone heaters. I know that it takes the heat well and does not yellow over time. It is a sealer designed for concrete but I have used it for stone on masonry heaters and exterior stone in MN and have never had an issue with it. It will give your stone a wet look for the first year, but after that the colors will still be enhanced and it will last about 8-10 years before it needs to be redone.
It does give off some VOC’s the first 2 days so you will not want to be in the house if possible. Yes VOC’s suck but I have not seen a water based sealer work for more than a year.
Just don’t let it get wet or rained on in the first day if an exterior application, it will turn hazy and you won’t be happy.

Thank you for your concise answer @SolidRock!

Thank you for the recommendation. Do you typically seal the rocks before or after putting the metal doors and clean out openings in?

We set our SR Doors that we manufacture into the brick or stone veneer as we are laying the exterior veneer.
So we tape and plastic the doors and then seal. If you have the option to seal before you install your doors then I would do that.

I second that. Wait to install the hardware until after you’ve sealed if you can.

I’m having a hard time locating the Cure n Seal 25lv to actually buy. It is out of stock and the product availability is unknown (ie no one can even order it for me). Do you have any suggestions as to where I might be able to purchase 5 gallons?


BASF MasterKure® CC 1315, 5 GallonThis looks like a different product than the Cure n Seal 25 lv, I like that it is waterbase, just checking in to make sure this is a product you have used and recommend?

The Brock White Company link I sent should have had the Brock White Cure n Seal 25lv product.
I have never used the BASF product below.

I have tried a few water based sealers or color enhancers over the years and have not liked the performance of any of them.

This is the closest thing I found on their website:

BW Crete Seal 25LV, 5 Gallon
0334075 MFG #: 51678539

Yup that’s the correct material

Thank you for your continued help. Here is a view of the stove before finishing:

Wow! That is some incredibly detailed and patient stone work! Beautiful!

Due to it’s toxicity it cannot be shipped ups, so I found a company in Denver that carried this:

Just wanted to check in one more time, as I don’t know what the difference is between the 25LV you recommended and 25% J22UV that I got? Any Ideas? I’m not sure how to even test it out?

This looks like it might be close to the same product that I have used in the past but Im not 100% sure.
You will have to find out if the product yellows over time. That is what you do not want.

No I don’t want it to yellow, my main concern is what it will do when heated, I’ll ask the distributor, but I doubt they will have any experience with it heating?

@dclaire, are you sure that you want to put a sealer on? The temptation to have a shiny look and more saturated color may be counterbalanced by the possible problems you might run into with the sealer including the yellowing mentioned or other long term aesthetic issues such as peeling, possible incompatibility or toxicity with heat, cost, challenge to acquire, etc.

@SolidRock Have you ever used mineral oil on rock for heaters? I know it’s been discussed for Soapstone heaters and am wondering if it has any application in this context. I have no experience with it. What do you think?