I still remember a gift a colleague gave me while on a business trip to Hong Kong - - an alum block. I didn't know what it was at the time or how to use it but it proved to be one of the most useful gifts I have ever gotten.
An alum block is the original antiseptic aftershave made of natural potassium alum which has antiseptic and astringent qualities. It can be used to help with healing minor nicks and cuts from shaving by constricting blood vessels and tightening pores. It can also help fight razor burn, improve skin tone, prevent ache and kill germs. It should be part of every man's shave kit.
Alum blocks are very easy to use. After you finish shaving and wash any remaining soap off your face, splash your face with cold water to help close pores and allow the alum block to easily glide over your face.
Run the alum block under cold water as this will make it glide over your face more easily. Make sure the entire surface is wet. Some people actually soap the block in ice water before use to increase the tingling feeling you will feel during use.
Rub the block gently across the areas of your neck and face that you shaved. Due to it's astringent qualities you should expect to feel a bit of tightness and tingling. Not to worry, this is normal and just the alum doing what it is suppose to.
While most people use alum on their face and neck, you can use it where ever else you might have shaven.
After use, rise the alum block with water, pat it dry with a towel and store in a dry place. If your alum came with a plastic case use that for storage. If you allow the alum to remain wet it will start to dissolve and shorten its useful life.
The most popular alternative are Styptic Pencils which are primarily used for individual cuts and nicks. They are made from a powered concentrate of alum crystal.
For travelers, Alum Matchsticks work really well. These matchbooks contain a small amount of alum at the tip of each matchstick. Simply tear off, wet the tip and use as explained above.
I highly recommending adding one of the items above to your shaving kit.