First the term waterproofing is a misnomer. If your boots did not come from the factory as waterproof boots, then it is very hard to make them completely waterproof now. But there are some products you can use to greatly improve their ability to withstand water, keeping your feet dryer longer.
Listed below are some products to help your non-waterproof footwear resist water more effectively, as well as, what products to use on your already waterproof boots:
*A note of caution… before putting anything on your boots find a small area and test the product to make sure it will not change the color to something you will not like.
*Follow the direction on the container for each product.
Mink Oil (paste): Very good waterproofing and conditioner for smooth leather. Good for work and outdoor environments. It will darken most leathers.
Sno Seal: (A beeswax based product) Very good waterproofing and conditioner for smooth leather. Good for work and outdoor environments. It will darken most leathers.
Silicone: (liquid or spray) Very good for waterproofing. It should be used on smooth leather only. Use for dress, work or outdoor footwear. It will not usually change the color of the leather, but always test to be sure.
Rain and Stain: (spray) Light waterproofing and stain guard. Best used for dress and street boots. It should not discolor most leathers, but always test to be sure. Most can be used on suede leather. Check label to be sure the one you are using can.
Suede and Nubuck Protector: (spray) When trying to protect suede leathers this is the product you should look for. Best applied after using a brush specially made for suede leather.
Care of Waterproof Boots:
In order to take proper care of your already waterproof boots, you’ll need to know how your boots were made waterproof before using any treatment on the boots. There two prevalent methods, the first uses waterproof leather and seam-sealed stitching. The second method uses a waterproof membrane that is breathable. The membrane is placed between the leather and the inside liner.
If your boot has waterproof leather, you would typically use a silicone product either in spray or bottle. I like the bottle type better as you have more control as you apply it. If your boot uses a membrane, you should not need to treat the boot for waterproofing. Just use a leather balm or light leather conditioner to help kept the leather from dry rotting. You will not want to use a heavy oil treatment it may affect the breathability of the membrane.