Step 1
Pour a little baking soda on the grout, then a little bit of vinegar. Watch it make a little volcano as the baking soda and vinegar mix together. Combining these products will get the dirty grout nice and clean.
Step 2
Scrub the grout stains with a used fabric softener sheet. You will see it clean immediately or after a few minutes, depending on how dirty your grout is.
Step 3
Rinse it out well with water. Repeat scrubbing with the dryer sheet if necessary.
Step 4
Let the area dry well before you place anything on your countertop again.
Source: www.Hunker.com