Here’s a helpful tip for getting really smooth drywall seam. After you’ve laid the tape in a four-inch bed of joint compound, apply another thin coat of compound with a six-inch knife. Let it dry overnight, then add another coat with a ten-inch trowel. Feather the edges out with the knife. Smooth it out again with the ten-inch trowel and let it dry. Apply your third coat the same way, this time with a 12-inch trowel. Increase the size of your trowel with each coat, and you’ll be sure to get an invisible seam every time.
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