How to Use Baking Soda on Carpets

Sprinkling baking soda on a carpet before vacuuming is one of the oldest tricks in home cleaning, and it still works for a simple reason: baking soda does not mask odours, it neutralises them.

Why it works

Most carpet smells come from acidic compounds trapped in the fibres: sweat, pet accidents, spilled food, general everyday use. Baking soda (sodium bicarbonate) is mildly alkaline, so when it contacts those acidic odour molecules it reacts with them and changes their chemical structure rather than covering them up. It is also slightly abrasive and absorbent, so it draws moisture and grease out of the fibres at the same time. A vacuum sprayed with air freshener does neither of these things; it just adds a new smell on top of the old one.

How to do it

1. Vacuum the carpet first to lift loose dirt and debris, so the baking soda can reach the fibres rather than sitting on top of surface dust.
2. Sprinkle it evenly over the carpet. A flour sifter or a large shaker with holes punched in the lid spreads it more evenly than shaking straight from the box.
3. Work it gently into the pile with a soft broom or brush, especially in high-traffic areas or anywhere there is a specific smell.
4. Leave it. Fifteen minutes handles light, everyday odour. For something stronger, like a pet accident or a musty room, leave it for a few hours, or overnight if the room can stay closed off.
5. Vacuum thoroughly, going over each section slowly and from a couple of directions so the machine picks up all the powder, not just what sits on the surface.

How much to use

A light, even dusting is enough, roughly what you would use to lightly coat a baking tray per square metre. More does not neutralise more odour; it just means more work for the vacuum and a higher chance of residue left behind in a thick pile carpet.

Test it first

On natural fibre carpets such as wool, or on any carpet with a colour you are unsure about, test a small hidden patch first (inside a cupboard, or under a sofa) and vacuum it off after fifteen minutes. Baking soda is generally safe on carpet but it is slightly abrasive, so it is worth checking on delicate or antique rugs before doing the whole room.

Getting it all out

Thick or long-pile carpet holds onto powder more than a low, tight weave. If you notice a faint white residue after vacuuming, go over the area again with the brush roll on, or use a handheld attachment to work directly into the pile. A carpet rake before the final vacuum pass also helps lift powder that has settled deep in the fibres.

Where else it helps

• Car interiors and boot carpets, using the same sprinkle-and-vacuum method.
• Mattresses, left for a few hours before vacuuming off, to freshen a mattress between proper cleans.
• Upholstered furniture, tested on a hidden patch first the same way as carpet.
• Trainers and everyday shoes, left in overnight and shaken out the next morning. Here's how to get the leftover powder out of shoes.

What it will not do

Baking soda lifts odour and light surface residue, but it will not remove a set-in stain or deep-cleaned ground-in dirt. For an actual stain, treat it first with a proper carpet cleaner, then use baking soda afterwards for any lingering smell.

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