I have exposed a brick chimney breast in a late Victorian (1885) terraced house in the north of England.
I've cleaned the bricks up and am really happy with how it looks. I've started looking into sealing the bricks to prevent dust, but I see a lot of conflicting information, with some saying that brick of that age shouldn't be sealed because it will cause moisture to move through the mortar instead of the brick, while others seem to think it's absolutely fine.
The chimney breast is in a party wall, so not external.
Should I seal this brick? I want a matt finish and I'm happy if the bricks darken slightly.
Best Answer
Usually the main purpose of a sealer is to protect against moisture. However, in your case the weather is not the issue, but rather appearance.
Silicones were developed to penetrate the brick and provide a coating to protect the brick. Those sealers were rated by how much silicon was in the sealer...2%, 3%, etc. The more, then the more expensive.
Clear sealers come in 3 types: 1) acrylic, 2) polyurethane, and 3) epoxy.
1) Acrylic is the cheapest and probably best for your use. It not too thick so it doesn’t look like a coating, but still gives the finish and protection against dust, etc.
2) Polyurethane will be too thick and give a thick appearance.
3)Epoxy is used primarily indoors because it does not have any UV protection AND you can select a finish: gloss, flat, etc., but is a heavy coating that does not allow the wall to “breathe”. If you use an epoxy sealer, make sure the wall is extremely dry.
Here’s an article that explains it better:
https://www.masonrymagazine.com/blog/2018/09/01/coatings-sealants-and-graffiti-protection/