The method of coloring shells

There are a lot of dead seashells at the beach of ocean, you can collect them and dye them at your liked colors, and the following is about the method of coloring shells:
The first: you can mix a 50:50 solution of bleach and water in a bucket at your home, and then place these seashells into the solution and allow them to soak until their periostracums have dissolved. The periostracum has the black, brown, golden-brown or pale yellow, and is the outermost layer of a seashell
The second: after a few minutes, you should remove the shells from the bleach solution, now you should use a toothbrush to scrape off any remaining debris.
The third: Clean the seashells well in the water. After you wash them, you can lay them out on a towel to dry for at least one week. It is important that these shells are completely dry before you color them.
The fourth: after a week, you should prepare the food coloring. Then you can need to submerge and soak your shells, mix at least 1 cup of each desired color. It is necessary that add vinegar per 1 cup of food coloring. The vinegar will help the color adhere to your shells.
The fifth, you should place the shells to soak until you have achieved the desired tint and depth of color. Now you can dry these shells completely.