8 Things You Should Never Do with CLR

updated 2 days ago
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Credit: Sarah Crowley/Apartment Therapy

Sometimes, despite your best and most consistent cleaning efforts, stains happen. This is often the case with hard water and rust stains. Not only are they unsightly, but over time they can also cause permanent damage to surfaces. Which is why, occasionally, one needs to pull out heavy-duty cleaners like CLR.

Quick Overview

What should you not use CLR on?

CLR should not be used on wood, clothing, wallpaper, carpeting, natural stones, brass, copper, aluminum, galvanized metals, and any painted, coated, or sealed surfaces.

CLR stands for calcium, lime, and rust and — as you may imagine — it is designed to clean these things specifically. Now, CLR is actually an EPA Safer Choice winner, meaning it’s a safer choice for humans and for the environment. But, it’s also a heavy-duty cleaning product that requires some precautions.

Here are eight things you should never do with CLR.

Don’t use CLR in an unventilated space.

Breathing in chemical fumes is never a good idea and CLR is no exception. Before using CLR, open windows and doors, turn on vents, and try to avoid being in an enclosed space like a shower stall with a closed door.

Don’t use CLR without spot testing it first.

CLR is acidic and can cause etching and damage to certain surfaces. According to the CLR product page, it shouldn’t be used on “wood, clothing, wallpaper, carpeting, natural stones, brass, copper, aluminum, galvanized metals, or any painted, coated, or sealed surfaces.” Always spot test first and clean spills immediately to avoid damaging surfaces through inadvertent contact.

Don’t leave CLR for longer than two minutes.

Again, CLR is acidic, which makes it effective, but also means it can cause damage if left in contact with surfaces for too long. Always rinse away with cool water after two minutes of contact.

Don’t use undiluted CLR.

Always dilute CLR with water. The ideal solution is one part CLR to one part water.

Don’t mix CLR with other household cleaners or bleach.

Mixing acids with bleach creates toxic chlorine gas. Mixing with other household chemicals can also result in toxic fumes.

Don’t use CLR in a spray bottle.

Spraying CLR creates a mist that can be an inhalation hazard. Instead, use a sponge, scrub brush, or bowl to clean the affected surface.

Don’t leave spills unattended. 

If any CLR spills or drips in areas that you aren’t actively cleaning, clean up spills immediately. You don’t want CLR to damage incompatible surfaces and don’t want to forget about the spill and leave it on a surface too long, which could also damage it. 

Don’t use CLR without reading the manufacturer’s directions on the item you’re cleaning. 

It’s important to make sure the item you’re cleaning is safe to clean with CLR. Double-check the manufacturer’s directions to ensure you’re not using CLR on an item that could be damaged.