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Dried road salt and deicer stains look nasty, and can actually damage your car. Wipe off spots and thin coatings with a soft cloth dipped in water or a solution of half water and half vinegar. In the event that your car is too dirty to spot-clean, take it to a car wash rather than wash the car in your driveway. Car washes send oily, polluted water off to the treatment plant, rather than letting it run off into storm drains and into streams.
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Anything that's weather-resistant, such as snow boots or water-repellent jackets, can be cleaned a soft cloth dipped in water or a water/vinegar mix (experiment with amounts; start with 1 tablespoon of vinegar in a quart of water, and gradually add more vinegar if needed). Then wipe them clean with a dry cloth. For everything else, just let the salt dry and then brush it off, either with a specialized clothes brush or an inexpensive hairbrush with soft bristles. It's incredibly fast and easy! Make sure beforehand that any mud is completely dry, too, or you will work it in rather than remove it. If the mud is ground into the fabric, start by brushing off what you can, and then toss the item into the laundry. If laundering is not an option, sponge the dirty areas with a moist cloth, and pat off the dirty water with a dry cloth (test the method in a small, hidden area of the clothing if you have any concern the fabric might get damaged). Move on to a water-vinegar mixture if plain water doesn't quite do the trick.
Salt can damage leather, so to preserve leather shoes it's a good idea to clean it off as quickly as possible. Dip a clean, soft rag in a one-to-one solution of water and vinegar and wipe away salt or dirt (you may need to do this repeatedly to get out all the salt). Saddle soap is also good for cleaning leather items, and is usually made from ecofriendly, natural ingredients. Rub the saddle soap onto a moist sponge then apply it to the leather in a circular motion, and buff it with a dry cloth. If you can't find saddle soap, make your own by melting two tablespoons of beeswax in a shallow, wide-mouthed Mason jar set in a saucepan of simmering water (do not heat the beeswax directly on the stove, as it can ignite if overheated). After the wax has melted, remove the jar from the water and stir in ½ cup of olive oil until blended, and stir in 1 cup of grated castile or Ivory soap and ¼ teaspoon of lavender or tea tree oil until blended (the oils are optional, but they offer some protection from mold, in addition to smelling nice). Store covered at room temperature.
If a misstep into a deep puddle of snowmelt leaves your shoes soaked through, remove any unattached insoles, dump out any water, and clean as above. Then stuff the shoes full of crumpled newspaper and allow them to dry. Avoid the temptation to put them near a heat source (and certainly not in the clothes dryer), as high heat may damage the leather more than getting it wet does. To speed the drying process, replace damp newspaper with dry as it soaks up the moisture.
After cleaning leather, and especially if it has gotten soaked, it's a good idea to apply some sort of conditioner. The simplest and safest is plain old olive oil: Rub on the oil with a soft rag, and allow the leather to absorb it (test a bit in an inconspicuous place first to see you like the effect or not). Continue to wipe on a thin layer of oil every few hours until it no longer seems to disappear into the leather. Buff off any excess oil with a dry, soft cloth. Another option: You can rub a beeswax-based leather conditioner onto your dry shoes or jacket to condition and protect them.
To get mud or salt stains out of suede, blot the suede item with a cloth dipped in undiluted white vinegar then blot the material until dry using a dry, soft cloth. Afterwards, brush the suede with a clean terry-cloth towel or soft suede brush in circular motions, raising the nap so the fabric looks clean and new.