Perspiration and grime can cause the underarm area of a shirt to turn into a dirty yellow color. This of course can ruin your clothes completely. Caused by the reaction of salt present in the sweat with the deodorants and other chemicals that we use, this yellowness in the shirts is pretty tough to wash out.
Simple soap, detergents and water will not do the trick. Try soaking the stained part of the shirt in diluted synthetic vinegar. The vinegar removes the stain causing salts by neutralizing them. Rinse the shirt and remove the vinegar completely. Then soak the shirt in warm water and liquid soap. Add to this a quarter cup of baking soda. Wash thoroughly and scrub with a soft plastic brush. When through, rinse again thoroughly and hang the shirt out to dry. If some residue still remains after drying, repeat the entire process again.
Very often, if you wash your clothes promptly, these stains will be completely removed. This would also prevent your clothes from getting further discolored. However, sometimes, it is not possible to wash the clothes immediately and it is then that the synthetic vinegar can help you out.
If your garment is stained, never iron it until the stain is gone. Ironing over the stain can help the stain set in permanently and you will end up ruining your garment. Also, don’t put your stained garment into a dryer. The heat generated in the dryer can set the stain too.
When you are buying perfumes, antiperspirants and deodorants, make sure they do not contain any ammonium chloride. Ammonium chloride leaves its own stains but when mixed with other salts from the sweat, these stains could last longer. There are also several aluminum compounds in these chemicals that cause the yellowing of the fabric at the arm pits. Spray your deodorants and antiperspirants directly onto your body and let them dry before you dress. This will prevent the chemicals from rubbing off onto the fabric.
There are several enzyme products available in the market. Use these to soak the stained garment for sometime before washing it. You can also make a thick paste of baking soda warm water and vinegar. Apply this paste on the stained area to remove them.
Ammonia, a good bleaching agent can also be used to remove these stains. However, be careful while using it. If your garment is dark in color, do not use ammonia because it might fade the color of your garment while taking out the stain.