This is what I do for making up henna paste:
I try to make up just what I am going to use, so I take a couple of tablespoons of henna powder and put it in a plastic container.Then I add lemon juice concentrate to the henna powder. I let the henna get about the consistency of thick mashed potatoes. Coverand leave out it sit out over night ( 8 hours) and in the morning, add 20 drops eucalyptus globulous oil. If you do not want to use essential oils, use olive oil, just be aware the essential oils will make the henna stain darker. After it sits for about 4-6 hours, I add warm lemon juice until I get the consistency of a thin frosting. I wait an hour and test the paste to make sure it is at dying capacity. To test the paste put a small dab on your palm and wait about 30 seconds, then wipe it off. If you have an orange spot the paste is ready. Fill the carrot bag with henna and tie off the large open end. Cut a small hole in the pointed end and use to fill the metal tip bottle. Once the bottle is filled you can start to draw. If the bottle is difficult to squeeze – refill. To Refill: take the nib with the metal tip off. tap down the remaining henna. gently squeeze the bottle, insert the carrot bag and fill, as the henna goes into the bottle release your grip on the bottle ( this creates a vacuum and sucks the henna in and there is less mess.) . I recommend sealing the henna with lemon sugar solution. Once the henna dries to a leathery stage , dab the design with a lemon sugar solution. ( 1/4 cup lemon juice concentrate with 2 teaspoons of sugar) Let dry and leave the henna on until the paste falls off naturally.
The henna should be good to use for the next 24 to 36 hours. When not using the paste freeze* it and it will be good for 6 months.
When using the paste after it has been in the freezer, let it warm to room temperature naturally and test it. Also for best results, avoid washing the paste off with water.
Tip: If it is difficult to get through the metal tip take 2 knee high nylon stockings & put one inside the other. Then take a couple heaping tablespoons of henna and put in the nylon. Put the nylon in a plastic bag hold all the open ends in one hand and use your other hand to squeeze the henna through into the plastic bag.
(*Double wrap in freezer bags when freezing. I also recommend freezing in small batches so you don’t have to re freeze.)