If you are making soaps, bath salts, butters and balms, bombs, butter bars etc you do not need to use a preservative. A general rule of thumb is if you product is anhydrous (without water) then you do not need to use a preservative.
It is important to remember your products are not going to stay as fresh as commercial products so making them in small batches is the better way to go. As with all products each has a different shelf life so putting a best before date on your formulations would be wise. Six months is plenty of time in which to use your products. Hopefully they will be so wonderful you and your customers will use them well within this time and return for more. It is also a huge selling point to say your products are completely natural and preservative free.
There is not really anything that can be termed a natural preservative. The closest is vitamin E but that only preserves the oils in formulations.
The best way to keep your products fresh and germ free is to:
- Store them in a dark cool place.
- Store them in air tight packaging.
- Make sure you work area is sterile and clean.
- Keep your hands regularly washed and clean.
- Use spatulas and spoons to handle your products specifically the end product. This will prevent contamination from fingers and hands.