Well back to the original problem with the yellow underarm stains. I know this doesn't help a whole lot but I believe the secret to this problem is prevention. When my husband had to wear dress shirts and a tie to work, he got horrible yellow stains under his arms and around the neck. I finally realized that I needed to spray Shout on the neck and underarms each and every time I washed and this stopped the problem from happening. It's been a while since I used the crystal but I looked at some pictures in google and I'm pretty sure it was Naturally Fresh and no it wasn't a spray, it was just a crystal of "salt" in a little plastic tube. Seems like you got it wet and smeared it around under your arms. I gave it to a friend that was telling me that's all she uses and she had no problem with it.

Hi, found this thread during research as I began to notice perspiration odors were not coming out of high-tech sports clothing - a typical problem as those fabrics have a long-standing reputation for retaining sweat odors. Some of the clothing was given to me, perhaps because the original owner couldn't deal with the problem, so I inherited the smell. But two shirts have been mine since new and I guess I let them get sweaty recently. So thanks to OP for bringing up the topic and for all the helpful answers. I've long been a fan of natural fibers, but being an active outdoor hiker and backpacker, have finally started using the polyester etc. high tech clothing. Many may not realize that for extreme winter snow sports, we avoid cotton, even as undies. It is called "death cloth" because it absorbs moisture and then loses its insulation value and can even freeze. Thus the move to fabrics that wick moisture away from the body and do not retain it. (And those are just the ones that get stinky.) I used a baking soda mash on the pits, then washed all the shirts normally. That did not work. So next I put them in the front-load washer in hot water with about a third of a cup of Oxiclean dissolved in it - a strong solution - and let them sit overnight before washing. Now no pit odor. Could've been just the Oxiclean that was successful or perhaps the action of the combo. Meanwhile I realize that prevention is the best idea so am rethinking my antiperspirant/deodorant, which for years has been unscented Mitchum roll-on. For some reason it is not quite as effective as it used to be, so I will acquire both Certain Dri and the Secret Clinical Strength to alternate with the Mitchum. I realize that I need to be careful to use both an antiperspirant AND a deodorant since I can't shower daily during the winter due to extremely dry skin. (Itching prevents sleep even after the application of lotion, usually Walmart's version of Aveeno Daily Moisturizing Lotion!) Again, thanks.

@ livebetter....Thank you for your very detailed explanation of laundry enzymes! While no specific enzyme will "deodorize", as we all know, enzymes aid in the the cleaning process of many proteins and molecules! I work out regularly. I wear anti-perspirant and deodorant DAILY. I do not like to sweat or smell like sweat. Many under arm deos and anti-perspirants adhere to fabric. Without enzymes, laundry detergent cannot thorougly remove the deo and anti-perspirant from the fabric. In turn, the fabric still smells, hence what I like to consier deodorizing! Before I am attacked for not using a "green" deodorant or anti-perspirant...I have tried DOZENS. I hate them all. I do not like to feel wet, and I do not like to smell of underarm odor. If I am putting a hole in the ozone, or killing some baby seal somewhere because I choose to use "real" deodorant & anti-perspirant...well, life sucks sometimes!! :) I do my part for the Earth (solar panels, recycle everything I can, I own a "green" car, all appliances are efficient and new, etc... But, I draw the line with deodorant!! LOL

The French cuffs would be treated like regular cuffs. I always used to use a pre-treat like Shout. Now that I discovered 'free and clear' type detergents with enzymes as well as 'free & clear' type oxygen bleach (Ecover), I don't use the Shout as often, unless I see cuffs that are really nasty. If nothing else works, I would try soaking the cuffs only in a bucket of hot water with the detergent. If you use a liquid detergent that has enzymes, perhaps use that as a pre-treat for 5 to 15 minutes before washing. I've done this with Persil Color Gel on my dark garments, with great success. HTH