Bleaching a Gray Shirt to Make It White?

It will take a quite a bit of bleach(I don't know how much) and probably have to soak for quite a while. Back in the late 70s my now "ex" had a pair of blue and white striped coveralls that he used when he went hunting in the winter and then one year he decided he wanted plain white ones, so I filled one of my laundry tubs up with hot water and poured a lot of bleach in it(not measured) and put them in the tub and let them soak until they more white than striped and then I took them out and put them in the washer for a good washing and rinsing.

The reason he needed the all white was so he would blend in better with the snow. Men!

Bleaching, or 'discharging' clothes to lighten or remove color can be helpful if you are going to cold-water dye, tie dye, and even to enhance the dramatic effect of printed or painted images. Bleach is a strong chemical, so here we will learn how to use it safely while effectively removing color.Bleach works best on cotton, rayon and linen. It will also work on synthetics like polyester.

Use warm, fresh bleach for the best results. Used and cold bleach are least effective.
Do not use vinegar to neutralize bleach because it can create a toxic gas.
Specialty bleach stoppers include Anti-Chlor and Bleach Stop.
Not all fabrics were created equal, and not all of them are prepared for the punch that bleach delivers. It will disintegrate wool and silk fibers.
.....with that being said , You may need to experiment with the strength of bleach that best fits your purposes. Try using 1 part bleach to 4 or 5 parts water. Always dilute the bleach, as straight bleach can damage clothing, irritate your skin, and ruin the other clothes in your next few wash cycles. Leave your shirt submerged for at least 5 minutes. Check it every minute to see if it has lightened to your liking. Keep in mind that it will be a shade or two lighter when it is dry.... , do not put the bleach directly onto the shirt!!! make sure that you fill the washer up with the bleach and water first!!! then submerge your gray shirt into the water and bleach.... do not wash it! ... just let it soak for about 5 mins and then check it! if its almost white but not quite there all the way yet then just watch it ..check it every 2 to 3 mins to see if its the white that you want it be or not yet,however if the gray shirt is to the white you desire then remove the shirt from the water and drain the water from your machine/tub , wherever you prefer doing it at/in, make sure to wear gloves to protect your skin from the effects of the bleach as it is a very harsh chemical compound :; Safety First!!! Bleach is strong stuff, so work outdoors if you can. Bleach is a very potent chemical with toxic fumes, and can stain wood floors and carpeting. At least work in a well-ventilated area if you can't go outside. Wear rubber gloves and an apron- you do not want to get this stuff on your hands..... and remember that the bleach will remain in your shirt after removal , so to keep it from eroding /wearing out your shirt , put your shirt into a mixture of hydrogen peroxide(hydrogen peroxide is/can be used as a bleach stopper!) diluted with water! After you are done dying, you need to stop the process of the chlorine. Rinse the fabric with water. You can use professional-grade bleach stoppers, but the most common household solution is hydrogen peroxide. It usually sells for under a buck at your local pharmacy. Soak your project in 2 parts hydrogen peroxide to 10 parts water. Soak for at least 10 minutes.
... make sure its cold water this time!!! after 10 mins you can then remove your now white shirt from the peroxide and water mixture and then just put thru the wash as usual !!! hope this helps!!! (: