Even if you carefully follow all the rules on keeping white clothes white, they can still become yellowed over time. So, what should you do?
There are several laundry products that will help brighten yellowed and dingy white fabrics. Start with one product and see if it produces the results you desire. Follow instructions and don't ever mix chemicals that might cause toxic fumes.
The most gentle method to whiten washable clothes is to mix a solution of warm water and oxygen-based bleach. Follow the package recommendations as to how much to use per gallon of water. Submerge the white garments and allow them to soak at least eight hours or overnight. Patience is required. Then wash as usual using the hottest water recommended for the fabric, adding 1/2 cup distilled white vinegar to the rinse water.
This process is safe to use on polyester clothes and all synthetic fabrics as well as natural fibers like cotton and linen. If you see improvement but fabrics are still not as white as you'd like, repeat the process with a freshly mixed batch of oxygen bleach. Do not use on silk, wool, or leather including any trim or embellishments made from those materials.
An old-fashioned laundry product, laundry bluing, can be added to the wash or rinse water to make white clothes appear brighter. Just carefully follow the directions on the bottle.
Commercial Color Remover
If neither oxygen-based bleach nor bluing gets your clothing white enough, use a commercial color remover such as Rit Color Remover to strip away any color from the clothing. It should not be used if there is colored trim or decorations on the clothing.
Use the Sun
If possible, line-dry white laundry outside in the sun. The ultraviolet rays of sunlight will help to whiten the clothes.
Chlorine bleach can be used on cotton fabrics that have yellowed due to storage issues. Always follow product directions, and don't use too much bleach. Check the label for directions concerning water temperature, too. Some chlorine bleach formulas (non-U.S.) only work in cold water, and heat inactivates them.
If you can detect a chlorine odor as you remove wet laundry from the washer, you are using too much bleach. Cut back on the amount used and add a second rinse to remove as much of the residue as possible.
Nothing Worked. Now What?
As a last resort, if you love the clothing and can't get the yellow out, consider dyeing the fabric another color. Today's dyes are more colorfast than those of the past. You should be able to enjoy the garment for many more wearings.
What Causes Yellowing of White Clothes?
Environmental factors like the nicotine from cigarette smoke or greasy cooking residue can cause fabrics to yellow. Underarm yellowing on shirts happens due to a reaction between your antiperspirant and body salts. Clothes that are stored improperly can react with the acids in a cardboard box or wooden shelves and turn yellow.
Chlorine bleach is great for cleaning and disinfecting but it can cause yellowing if overused or if used on white synthetic fibers like nylon, microfibers, or polyester. The bleach weakens the fibers and returns the synthetic polymers back to their original color, yellow.
Even white fabrics made from natural fibers like cotton and linen can turn yellow if they are exposed to too much chlorine bleach. Overuse of chlorine bleach can also cause white clothes to yellow when hung on a clothesline outside to dry because the sun adds another layer of bleaching due to ultra-violet rays. Bleach can also cause the protein in sweat to permanently bond with cotton, creating a yellowed stain.
And, if you are using too much detergent or fabric softener and not rinsing well, the high heat of the clothes dryer can "bake" the residue into the fibers and leave them grey or yellow.
How to Store White Clothes to Prevent Yellowing
Before storing white clothes, even for just a season, make sure the garments or linens are completely clean and stain-free by laundering or dry-cleaning each piece. If you are not sure if the item is clean, it's worth the effort to wash it just to be safe. Be certain that pieces are completely dry before packing away. Wash and dry your hands before handling the item because lotion or creams can discolor white items.
Choose a cool, dry space for storage. Avoid extreme temperature areas like attics, basements, and garages. It is important to use the right type of storage container to prevent yellowing. One choice is to use storage boxes sold for archival storage. You will also need to purchase white archival tissue paper. It must be both acid- and lignin-free.
However, if you are concerned about the box getting crushed or the expense, purchase a plastic storage box. The box must be made of cast polypropylene to be safe for your keepsakes. Look for the #5 within the recycling triangle symbol or the letters “PP” to be sure that you have the correct type of plastic that will not emit damaging chemicals.