No. You do not have to add any thing to preserve the taste or color if you get the job done in one sitting.
If you get tired and need to finish the next day, take it out of the can! Put it in a plastic container with a tight lid. The can will start to rust very quickly. Yuck.
Put in just a few drops of lemon or lime on top with a tiny little bit of water to keep the top from turning brown then get back to the job ASAP.
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