Whenever a buyer posts a project that requires "sealed bids", all bids for that project are sealed. A sealed bid is a bid in which the dollar amount of the bid is kept private between the buyer and the bidder. You cannot seal a bid yourself; the system does this for you, but only when a project is defined to require sealed bids. If you have submitted a bid on a sealed project, it will be unsealed only for you and for the project's buyer. To all others, the bid will be sealed.