Preservatives: I know some people are really against preservatives, but I will not allow anyone to leave my classes or my workshop with adequate preservation. There are no "natural" preservatives, but you do have a range from which to choose. I like Germall Plus - it can be used at levels from 0.1 to 0.5% for most products, and it is affordable. Germaben II is also a good choice. There are others like Optiphen or Suttocide, but I know nothing about these, so I can't really help much. Some preservatives can alter your pH or emulsification, so research your preservative before you use it. Learning to preserve is an art in itself, but using Germall Plus or Germaben II is the easy way to start as they are easy to find and shouldn't mess with your pH or emulsification.
Measuring vs. weighing: As different ingredients have different densities, you will want to weigh your products. Get yourself a good digital scale that measures 1.0 grams (or up to 0.1 grams if you want to make more mineral make-up!) from a kitchen store (London Drugs has a good selection and great prices) or a supply store (Voyageur carries the Escali line for about $40 to start, and these are great!) For some things, like the toner, we could get away with measuring in measuring cups, but this just isn't as accurate as I'd like.
How to interpret recipes: A lot of recipes are listed in terms of percentage, so the entire recipe will total 100%. This makes it easier to make larger batches. If you are making a recipe with percentages, just convert the percentage to grams. If a recipe calls for 80% water, in a 100 gram batch you'll use 80 grams of water. If you want to make 300 grams of the recipe, you'll multiply the entire recipe by 3, so you'll use 240 grams of water. This goes for every ingredient, so if you need 20% oils, you'll add 20 grams of oil, and so on.
Fragrance oils: Please use fragrance or essential oils from reputable retailers (see the side bar for my favourite local suppliers). Do not use perfumes. We found this out the hard way: We made milk bath with Poison and it smelled horrible the next day! You can find water soluble oils at Voyageur, which are great for body sprays, body washes, bubble baths, and other things in which you wouldn't normally use an emulsifier, but most you'll find will be oil based.
Proper techniques: We use the heat and hold method for making lotion and other recipes containing water. This means you should heat your ingredients to 70C and hold it there for about 20 minutes. Now this does mean that some of your water will evaporate, so make sure you put in more than you need and weigh it again before combining. When adding preservatives, fragrance oils, or other heat sensitive ingredients, make sure you have a thermometer to tell you when you've reached 45C.
Packaging: Please do not re-use bottles. You can get really nice bottles at the dollar store or at the supply stores listed on the right. Re-using bottles might seem like a good idea, but if you have bacteria or other nasties in your bottles, you've contaminated your products from the start!
Labelling: This is a fun part of making your own products - coming up with names for the products and fragrances, adding your own pictures, customizing what you make -- and it helps when you want to re-make the products by adding the ingredient list. Make your labels waterproof by using waterproof inks (like Epson inks) on your printer, and spray with Krylon Make It Last! to ensure the labels don't come off under water.
Scale (see above for more information)
Pyrex or heat proof jugs
Double boiler - make one on your stove with a pot and some water
Funnels to pour your creations into bottles
Pipettes (optional - great for small amounts, like fragrance oils)
Various spoons and forks you use only for making products.
A FEW THOUGHTS...
When I'm making a product, I ask myself what is my end goal? For instance, with my body wash I want to create something that has good cleaning power, good lather, a pleasant smell, and moisturizing abilities. So I need to choose my surfactants and additives carefully to ensure I get this end result.
So you've got all this stuff...what next? Tomorrow, tune in to learn how to make a facial toner!