With so many chemicals out there to protect your metal from fire scale (blackening or charring of the metal when firing), I really wanted to find a safe product to use because of my animals. My children are old enough that I don't have to worry about them touching my products but if you have little ones this is also a great option for you. There have been mixed reviews about the effectiveness with this...but it works for me. It leaves very little fire scale that is easily removed with my dremel or some fine grit sand paper. Now I just wish that I could find a natural flux to use. It's the only chemical that I use while making jewelry.
I use 1/2 cup luke warm water, with about 1/8 cup distilled white vinegar and 2-3 grinds of Sea Salt (using a salt grinder I turn it 2-3 times). I keep it stored at room temperature in a plastic glad container with a lid. After firing and quenching I drop it in the pickling container for about 1/2 hour...you can keep it in there longer to remove more fire scale, but as I've said in previous posts, I tend to be a little impatient! ( You may have to play around with the mixture a bit to find what works for you, but the one listed above is what I use)
For oxidizing there are a few different options chemically, most popular being Liver of Sulfur, again a very toxic chemical. The option I use is eggs. I hard boil 3 eggs, put them in a glad plastic container, crush them with a spoon (shells and all) . Another thing I do is take some stretchy plastic threading for beading or you can use thick thread (you can get creative here), I tie knots in it to act as a stopper or a divider to keep the metal from touching then lay it across the top of the plastic container and put the lid on it. It suspends the metal from the eggs and allows me to reheat the eggs for a darker patina without having to dig out the metal. I normally only reheat the eggs in the microwave once (about 30 seconds) and leave the metal to oxidize for a total of an hour. The great thing about using a clear container is you can decide how dark you'd like your pieces to be. I had a really cool rainbow effect on one of my pmc pieces that I thought about keeping like that but went ahead and let it sit longer to achieve a very dark patina.
These are just methods that I use to give me my own peace of mind and are in no way meant to put someone else down for using chemicals. Actually using chemicals makes the whole process a lot faster, but I just choose to use these methods.