We've all seen magicians toss magic powder into the air with a flourish, resulting in colored smoke, a disappearance, or a cute bunny showing up unexpectedly. In many ways loose incense has that same sort of magical effect (without the bunnies). Set some resin blended with herbs or woods to a sufficient heat source, and the air is infused with scents evocative of wooded glens, summer gardens or autumn cookspaces.
Years ago my sister and I were the herb ladies at a local renaissance festival. We were known for our "herb walls", pegboard lined walls which held hundreds of pre-weighed ounce packages of herbs. We kept what we called a "shake" bag of all the bits left over after weighing the pounds into ounces. Our antique scale never gave us more than 15 ounces per pound, so there were always leftovers. In order to create interest and draw customers, we kept charcoal disks burning and periodically sprinkled a pinch of this random blend over them. So began our love of incense making.
This loose form of incense is the simplest, and in many ways the most creative method. Whereas formed incense line cones and sticks require very specific measurements and ratios of ingredients, there are no such barriers for loose blends.
Most often, a very scant pinch of the blend smolders upon a specially made self-igniting charcoal disk. Care must be taken because indoors the smoke can be overwhelming unless a light hand is used. Resins can be simmered in water; a blend of lavender buds and frankincense is lovely simmered or smoldered. Blends can be tossed into campfires or heated woodstoves. For the most part though, incense is burned.
Blending is where personal preferences come into play. For instance, to me a blend starts with a resin (pine, copal, myrrh, frankincense, dragon's blood, etc) but may not be at all important to someone else. Yellow sandalwood was at one time de rigueur but in recent years it has become too precious and so we save it for very special blends and use it sparingly. Powdered or cut and sifted fragrant herbs and spices are good inclusions. Many other symbolic additions are possible in small quantities too.
We live on a Christmas tree farm, and the trees are trimmed each summer. In the fall and again in January, I gather the drying drops of sap that results from the cuts to the trees and put that sticky mixture in the deep freeze for a year to dry out. It is my favorite resin to use for personal blends because it means a lot to me.
Along with that, I blend herbs that I've grown over the summer. Lavender, thyme, lemon verbena, sages, basils, mints, and many other plants from the garden or found in the wild can be used. Incenses can be made in a way that uses the language of flowers to make them meaningful, they can be carefully designed, or they can be a haphazard mixture of the things that make you happy.
Sometimes burning changes the scents of substances in surprising ways. To find out if a scent remains true, light a charcoal disk and burn the tiniest pinch of each of the substances being considered. It was a surprise to us that orange peel was unpleasant when burned.
Essential oils (and synthetic fragrance oils) almost always retain their true scents when burned, and a very small quantity goes a long way.
As always, record the blend as it is being created. It would be sad to stumble upon the ultimate blend and not be able to duplicate it.
Make very small batches. If it is perfect and the recipe is recorded, more can always be made later. If it doesn't turn out as was hoped, using a teaspoon measure or smaller as "a part" (as in one part resin, 1/2 part lavender, 1 part rose petals, 2 drops patchouli essential oil, for instance) means that much less material will be wasted.
Most importantly, enjoy the process and trust your own creativity. Going back to our shake bag from the renaissance faire, it should be fairly clear that it is difficult to blend a loose incense that is bad.
Some people require something like a recipe, so in that case here is one of ratios that I tend towards:
1 part resin (small chunks or powdered)
3 to 4 parts dried botanicals and/or wood powder
1 drop essential or fragrance oil per teaspoon (optional)
Store in an air-tight container out of the light and it will last for years. Depending on the ingredients the scent might fade somewhat as years pass, but I have some that is close to 2 decades old that are still delightful.
Some simple blends...
1 part myrrh
2 parts ground patchouli
2 parts ground lavender buds
4 drops patchouli essential oil
1 part copal
3 parts white sage
1 part cedar tips or ground wood
grind together in mortar and pestle
1 part frankincense
2 parts lemon verbena
2 parts rosemary