If you are going to work with pinecones that you pick up yourself, get them as soon as they start to drop. If you wait, the cones will start to deteriorate and may not be useful. I like the size and shape of cones from red pine trees for the decorations I make with miniature birds.
Finished Pinecone
As with all found materials, you must make sure that it is free from dirt, seeds, insects, fungus and molds. This is my process for pinecones.
1. When you get the cones home, brush them off with a dry paint brush to remove surface dirt. A damp cloth works if you have very dirty cones.
2. Use compressed air to blow out seeds, dirt and insects.
3. Evaluate each cone to make sure it will meet your needs and discard any damaged ones.
4. Put the cones on a tray in a dry location to air dry. You can put them in the oven at 200 degrees Fahrenheit for about an hour to an hour and a half and this will dry them out and kill insects. This however can make the cone scale too brittle, and it may crack if drilling to mount something.
5. After air drying the cones and they look like they have opened as far as they are going to, use compressed air and tweezers to again remove seeds and any debris.
6. Finally, spray them with 2 or 3 coats of clear finish.
Your cones are now ready to use for any project.