One of the most contaminated areas of a shirt is the collar. In this part, it most closely adheres to the body, moreover, the neck often sweats. You can, in addition to household chemicals, try the advice of housewives.

Instructions
Step 1
Before washing, pay attention to the type of fabric from which the shirt is sewn, indicated on the tag, and select the washing mode according to the instructions.
Step 2
To clean your collar, try rubbing it with laundry soap first and letting it sit for a couple of hours. After that, machine wash your shirt as usual using your usual powder.
Step 3
Some women suggest using dishwashing detergents that dissolve grease in a similar way. Try treating your collar with this product before washing, then let it sit for half an hour and wash as usual.
Step 4
Treat the soiled collar with a cotton swab dipped in vinegar, then place it in the washing machine. If you are dealing with a colored shirt, then first try how the vinegar works on the fabric in an inconspicuous area. It can cause discoloration of the fabric, so be careful.
Step 5
Also try cleaning the collar before washing with a mixture of alcohol and salt. To prepare it, take four parts of ammonia and one part of table salt. Stir and add four parts water. With this mixture, thoroughly wipe the collar, leave for ten minutes for best action, then rinse with warm water.
Step 6
Use talcum powder. Cover the collar with talcum powder in the evening and wash as usual in the morning.
Step 7
Use a stiff brush. Moisten the brush and scrub vigorously before washing. A soapy solution can be used to be effective. Then wash in the machine as usual. This method should not be abused; with frequent use, the fabric will quickly fray.
Step 8
Many people advise changing shirts daily to avoid heavy contamination. Perhaps this method will be optimal, especially when it comes to white shirts.