According to A Cleaner World (a professional dry-cleaners' site),
Here’s how we suggest combating the impact of both perspiration and antiperspirant on your clothes:
Check out the ingredients in your antiperspirant, and if it contains aluminum chlorohydrate, which tends to clump in cotton and
damage fibers, consider switching to another product – like an
aluminum-free or neutral pH type of deodorant.
Always allow your deodorant to dry before dressing, which should help with getting it on your clothes.
- Just as with stains and spills, wash or dry clean your clothes right after wearing to remove as much of both the perspiration and
antiperspirant as possible.
- If stains remain, don’t place the item in the dryer or iron it. The heat from both the dryer and the iron will cause the stains to
permanently set into the fabric.
- If washing doesn’t remove the stains, then try soaking in cold water and a small amount of dish soap that contains de-greasers.
After soaking, rinse, and wash according to the manufacturer’s
- If that doesn’t work, you could try soaking in a mild color-safe bleach, using the same instructions as above. Never use chlorine
bleach to removed sweat stains, even if it is a white garment. The
proteins from the sweat will react with the bleach and make the stain
- Remember - there are times when the damage is too much, and the garment is past being restored.
It looks like your boyfriend is going to be shopping for t-shirts soon.
Preventative (Bonus Round): As the first point mentions, your formulation may be a different pH, different amount of aluminum chlorohydrate, you have fewer cotton garments, or have cotton blends which react in a different manner than 100% cotton. Your application technique may vary (second point). etc., etc.