A greasy oven is one of those jobs that quietly gets pushed to the bottom of the list. It still works, after all — until the smoke alarm goes off halfway through a Sunday roast, or everything you bake starts tasting faintly of last week's sausages. The good news is that you don't need a caustic, eye-stinging spray to sort it out. With a tub of bicarbonate of soda, a bit of patience and an overnight soak, you can get the interior genuinely clean using things you already have in the cupboard.

Why It's Worth Skipping the Harsh Stuff

Most supermarket oven cleaners rely on sodium hydroxide — essentially caustic soda — to dissolve baked-on fat. It works, but it's unpleasant to use: the fumes irritate your throat and eyes, it burns skin on contact, and it can dull enamel and dry out the rubber door seal over time. You need gloves, open windows and a fair bit of nerve every time you reach for it.

For a domestic oven that's cleaned a few times a year, that's overkill. Bicarbonate of soda is mildly alkaline, which is enough to break the bond between baked-on grease and the enamel, and it's gentle on surfaces, safe around food and completely odourless. The only real ingredient it needs is time.

What You'll Need

• A tub of bicarbonate of soda — budget on a good few tablespoons, more for a really dirty oven
• Washing-up liquid and warm water
• White vinegar in a spray bottle, diluted roughly one part vinegar to one part water
• Rubber gloves, even though this is gentler stuff
• Several clean cloths or microfibre cloths, plus a non-scratch scourer
• An old credit card or a plastic scraper for stubborn patches
• An old towel to protect the floor, and a large basin or the bath for the shelves

Mixing a Paste That Does the Work

Tip four to six tablespoons of bicarbonate of soda into a small bowl and add water a little at a time, stirring until you have a thick paste about the consistency of natural yoghurt. A squeeze of washing-up liquid helps it cling to vertical surfaces rather than sliding off.

Put your gloves on, then spread the paste over the interior walls, the base and the inside of the door with your fingers or the back of a spoon. Thick smears are fine — you're not aiming for neat. Two things to avoid: keep the paste off the heating element at the back or top, and don't push it into the vents of a fan-assisted oven. A damp cloth wrapped round your finger is the easiest way to clean right up to the edges without smearing paste where it shouldn't go.

If your oven has a pyrolytic self-cleaning setting, you can still use this method for everyday grime — just make sure every trace of paste and grease is wiped away before you ever run the cleaning cycle.

Leave It Overnight, Then Wipe

This is the part where you do nothing at all. Close the door and walk away. Leave the paste for at least twelve hours, ideally overnight. Bicarbonate of soda softens grease slowly, so the longer it sits, the less scrubbing you'll do in the morning.

Next day, fill a bowl with warm water and a good squirt of washing-up liquid. Wipe the paste away with a damp cloth, rinsing often. Most of the grease will come off with it. For anything left behind, spray the area with your diluted vinegar — it will fizz gently as it neutralises the bicarbonate — then wipe again with warm soapy water.

Stubborn brown patches may need a fresh dab of paste and thirty minutes rather than a full night. Use the plastic scraper at a shallow angle to lift them, then wipe clean. Finish by rinsing every surface with clean water and drying with a cloth, so no chalky residue is left to bake on next time.

The Door, the Glass and the Shelves

The wire shelves are usually the hardest part, because they're awkward to scrub in place. Take them out and soak them overnight in the bath or a large basin filled with hot water, a couple of scoops of bicarbonate of soda and a generous squirt of washing-up liquid. In the morning, a quick going-over with a non-scratch scourer will shift almost everything.

For the door glass, apply a little of the same paste, leave it twenty minutes, then wipe with warm soapy water and buff with vinegar spray and a dry cloth for a streak-free finish. If your oven door has removable inner panes, taking them out makes the job far easier — but check your model's manual first, as some are not designed to come apart.

Wipe the rubber door seal with warm soapy water on a cloth rather than soaking it, and dry it thoroughly afterwards. Saturating the seal can shorten its life, and a worn seal means heat escaping and food taking longer to cook.

Small Habits That Keep It Cleaner for Longer

• Stand a baking tray on the shelf directly below whatever you're roasting, to catch drips before they hit the base.
• Wipe the interior with a damp cloth while the oven is still slightly warm after cooking — not hot — and grease comes away in seconds.
• Cover casseroles and pies loosely with foil, which cuts down on spitting fat without affecting the bake.
• Give the shelves a hot soapy soak once a month rather than waiting until they're blackened.
• Deal with spills the same day where you can. Ten minutes now saves an hour of scrubbing later.

Give the overnight bicarb method a try on a Friday night and you'll have a clean, fresh-smelling oven by Saturday morning — no fumes, no gloves full of caustic gel, and no lingering chemical smell the next time you bake a batch of Yorkshire puddings.