No need to scrub, put the oven rack in a bag: it becomes like new again

Place the oven rack into the plastic bag.

Add 1/2 cup of ammonia into the bag (you don’t need to soak the rack — the fumes do the work).

Seal the bag tightly and leave it overnight (8–12 hours) in a well-ventilated space or outside.

Next day, open the bag in fresh air (to avoid the strong smell), and remove the rack.

Rinse with warm soapy water — the grime should wipe off easily with a sponge or cloth.

Dry and return the rack to the oven.

Tip: Never mix ammonia with bleach or other cleaners — the fumes can be toxic.