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In some instances, it might be best to install the yarn bomb during daylight hours. Other times, you might find it more beneficial to install it at night, when few others are around to interfere.  Yarn bombing during the day will likely make it impossible to remain anonymous, but if secrecy is not important to you, the daylight will make it much easier to see. If you want to remain anonymous, you will need to pick a time of day when very few people are likely to be around. Usually, this means installing the yarn bomb at night. Aside from your yarn artwork and installation tools, you may also need to bring a few helpers with you.  You will need to bring a yarn needle, matching yarn, and scissors to actually install a crocheted or knitted piece. If you are latch hooking or cross stitching, bring the tools you would usually use to create a piece of this nature. Take your diagram, as well, so that you can check your work against it as you move through the installation. You should also bring along a ladder if you need to reach tall places and a flashlight if you are working at night. Even if you think you can install the yarn bomb on your own, it is a wise idea to bring at least one friend with you if you are doing the work in the evening or at night. Use your diagram as a guide as you wrap each piece of yarn artwork around the appropriate part of the object. Hold each piece in place with safety pins until all of the pieces are in their correct position. If you are cross stitching, latch hooking, or wrapping, you won't have any previously created pieces to wrap around the work. Instead, you will need to use the object itself as your canvas and create the entire work on scene. Use additional yarn and a large yarn needle to stitch all the seams together, holding the yarn bomb in place more securely. Once everything is in place, you can remove the safety pins previously responsible for holding the pieces together. Use a simple stitch to make the process as easy and quick as possible. For instance, a whip stitch is usually a good choice. It is crucial that you do not cause any damage to anyone's property while installing your yarn bomb. Aside from man-made property, like benches and signs, you should also avoid damaging the plants and animals living in the area.

Summary:
Go during the best time of day. Bring everything you might need. Wrap each piece around the object. Sew seams to install the yarn bomb. Never cause any property damage.