The thermometer will come into contact with oil sprays, baking powder, and other bits of cooking debris during its lifetime. Keeping the surfaces clean will prevent readability problems.
Ensure that any glass in the packaging is waterproof before using it to ensure you’re getting the most accurate readings. Next, make sure the thermometer is cool before using it. Wash with warm water and mild detergent, scrub with a soft washcloth, and then rinse and dry right away.
When dealing with particularly tough stains, and the above does not work, make a paste of baking soda and water, and then spread it over the face of your thermometer. After it has been on for about 15 minutes, wipe it clean with a soft cloth. It must be dried immediately. Baking soda can remove virtually any kitchen stain.