They are not great for sugar scrubs or whipped butters. Many have tried, few have succeeded. It would be nice, but those products clog up the orifice and lead to heart break. They do not work for liquid products, like toners, as they'll leak out. They are generally made of HDPE, which means they shouldn't contain a ton of essential oils, but they are easier to squeeze. So if you want to get out every last drop, consider the malibu or tottle bottle.
As a final note, they are kind of annoying to fill because you can never get that last bit at the top filled! If you don't want to hear about how you didn't give someone a full bottle of product, consider getting the opaque bottles!
For thick lotions, body butters, anhydrous whipped butters, balms, sugar scrubs, and anything too thick for a bottle, consider the humble jar. So many uses, so many sizes, and so many reasons to use a jar.
Jars are generally cheaper than bottles, and they come in a variety of sizes. They generally have the same shape, but you can choose from a domed cap or a flat cap (this is the domed cap to the right). You can choose from frosted, white, or clear or double or singled walled. There are advantages to each, and most of the time it is a personal choice.
The clear jars tend to be made of PET, which means they are suitable for products with high levels of essential oils. The frosted jars tend to be made of polypropylene, so they can withstand high temperatures, and they would be suitable for some essential oil levels, but not high ones.
What's the point of using single vs. double walled jars? I really haven't found any good reasoning behind using either. I tend to use the double walled jars because I can find them easier and they look nice. I'm sure there are reasons like the ability to fill them at higher temperatures, but I'm not filling at high temperatures, so that point is moot to me.
Jars are always a lovely thing to have around the workshop. You can put most anything in a jar - thick hair conditioners, bubble goo, thick creams, thick lotions, body butters, anhydrous whipped butters, balms, and so on - except for products like toner or spray on perfumes. You can get smaller jars for lip balms, solid perfumes, and balms.
Should you go low profile or regular opening? I like low profile for sugar scrubs: It's easy to scoop a handful out when you're in a rush to get some lovely scrubby action! Low profile is generally more expensive, and the ones I've found tend to be clear PET jars rather than frosted, double walled HDPE jars. (Not that this makes a difference, but if you're a fan of the frosted jar, it might be harder to find.)
And consider investing in some dust covers for your jars. They look nice when the person opens the jar, and they will keep the contents from sloshing all over the place.
A note on glass jars: They look awesome and decorative and you have many choices, but they aren't a good choice if you have to place them somewhere they might break. The bathtub is not the ideal location for a glass container. If they slip and fall, this could be dangerous. Glass is, however, great for bath salts and other things that need to retain its smell, and they can be found very cheaply at thrift or bargain stores.
Metallic containers - slip tins, little round tins - always look really cool, but they are only good for products that do not contain water. So lip balms, balms, and whipped butters are awesome here. Do not use them for anything that might come into contact with water, like sugar scrubs. I learned that lesson the hard way...EEW!
Well, I'm off to play in the workshop - I'm out of sugar scrub and I need some serious moisturization! Join me Thursday for more super happy fun discussion about packaging! (Tomorrow is mineral make-up Wednesday!)