Showerthought: My mild mix for old chimneys breaks the rules

Many sweeps use strong cleaners on old brick. I found a mild mix works just as well without harming the mortar. It's a skill I picked up from working on older houses.

4 comments

4 Comments

richarddixon1mo ago

Hey, that's actually really smart. I mean, strong cleaners can eat away at old mortar over time. Idk, maybe it's just me, but keeping the original stuff in good shape always seems better. A mild mix gets the job done without all the damage. It's like working with the house, not against it.

mary_hernandez1mo ago

But is the damage really that bad? @phoenix_burns28 mentioned instant chemical damage, but I've seen strong cleaners used on old brick with no visible harm. Old mortar isn't always as fragile as we think. Mild mixes are good for maintenance, but tough stains might need something stronger. The key is to test a small area first. That way, you can clean without fearing you'll destroy the original work.

lewis.gray1mo ago

Mary makes a solid point about testing first, I used to grab the strongest cleaner too. Seeing phoenix explain the instant chemical reaction on old lime mortar was a real eye opener for me. It's not just wearing it down slow, it can wreck the structure right away. You might not see the harm at first, but the damage is done. That's why a gentle approach is smarter for anything historical.

phoenix_burns281mo ago

Wait, is it actually eating away over time though? Strong acid-based cleaners can cause damage right away on old lime mortar, because it reacts with the material. It's less about slow erosion and more about a bad chemical reaction that pits and weakens it instantly. Modern cement mortar handles acid better, but that old stuff doesn't.