Generally used in home pickling to add crispness.

In Ayurveda, alum is termed saurashtri. It is generally known as ‘Phitkari’. It has its important place in Ayurvedic medicine and can be used as a home remedy. It has various external application to cure wounds and other diseases
According to Ayurveda, alum has the following properties:

• Antiseptic
• Haemostatic
• Astringent
• Anti-pyretic
• Anti-inflammatory
• Antibiotic

Health Benefits of Alum
Alum is used for the cure of following disorders:

• Wound
Alum powder can be applied on any injured area to stop blood loss and also to provide an antiseptic cover to a wound.

• Itching
2 teaspoon of lemon juice should be mixed with a small amount alum powder. Apply this mixture on itchy skin.

• Acne
Make a mixture by adding powdered alum to 1/4 cup of with hazel and apply it on the skin to get relief from acne or pimples.

• Skin tightening
Alum powder mixed with rose water if applied on face and washed after 10 minutes makes the skin tight by closing the pores.

• Tonsillitis
Alum is effectively used for cure of tonsillitis in Ayurveda. A mixture prepared by mixing 2 pinch of alum powder, ¼th teaspoon of turmeric in 1 cup of warm water. This mixture should be used for gargle to treat tonsillitis.

• Complexion enhancer
Boil water with phitkari and let it cool. Wash face with this cold water which lightens the complexion and tones the skin.

• natural deodorant
Alum can also be used as a natural deodorant as it inhibits the bacterial growth

Other Potential Uses
Alum powder is used to treat cold sores and is also applied to cuts or abrasions to prevent and or treat infections.

Treating feet odor
Wash your feet with warm water and a moisturizing soap. Use a clean towel to dry your feet and between your toes.
Sprinkle alum powder into a basin filled with warm water. Soak your feet nightly for 15 to 20 minutes. Dry them thoroughly. Sleep barefoot, allowing your feet to air out during the night.
Sprinkle alum powder inside your shoes daily. Alum powder will alleviate foot odor by absorbing sweat from your shoes. Avoid wearing the same shoes for two consecutive days.

Use to purify water
Pour eight-tenths of a gallon of contaminated water into the reaction vessel -- a sturdy glass container. Be sure that there is enough space in the vessel that the contaminated water can be stirred without spillage.
Add 1.4 ounces of alum powder to the contaminated water in the reaction vessel and carefully stir the mixture with the stirring stick for at least five minutes. Sediment will form as the phosphorous in the water binds with the alum powder.

Attach the liquid storage container intended to hold the purified water to the filtration apparatus. This container should be marked or labeled to distinguish the purified water it will hold from other containers that may contain contaminated water.

Filter the water-alum mixture through a filtration apparatus. The filter will allow the purified water through while trapping the alum-phosphorous mixture. The purified water will collect in the liquid storage container and be used without fear of phosphorous contamination.

Although alum serves to purify water of its phosphorous content, it is important to remember that purified water may need to be sterilized prior to consumption. Add a germ killing agent to the purified water to be sure it is fully disinfected.

Do not drink either the contaminated water or the water-alum mixture. Until the water is passed through a filter the phosphorous will remain present and can potentially be hazardous.

Ingredients: Aluminum sulfate

Origin: United States
Kosher: KSA Certified
Notes: aka cake alum, filter alum, papermaker's alum, alunogenite, aluminum salt, Crystal Pure™, ammonium aluminum sulfite or ammonium alum
CAS: 17927-65-0

Reference:
wikipedia.org
ehow.com
ygoy.com