HOW TO 1ST COAT DRYWALL BUTT JOINTS
(What's A Butt Joint??)
Butt Joints happen any place two ends butt up against each other. Unlike the tapered edges on the top and bottom of sheetrock, butt joints are just flat (There is no cavity to fill with mud). If you were to take a wide knife, and place it on a butt joint, you will see that not only is it flat but many times you will be able to rock the knife back and forth because it's a little humped already. What you are trying to do is build up the mud on each side of the tape to make the joint as flat as possible. You don't want to make a bigger hump.
The picture below gives you a rough idea on what you're trying to do here. 1st coat (Yellow) you will use a 10 inch knife. Build up each side of the joint. The 2nd coat (Blue) you use a 12 inch knife, coat the middle of joint.
This might not always be the case, every butt will be different. You might have a butt that is still humped after the 1st coat, in that case you would build up each side again with the 2nd coat. You will understand better when you vuew the video.
Step 1: Mix Mud
Mix up your mud. To learn all about mud and how to mix go here All about Joint Compound
Thin your mud down with a little water. Mud straight out of the bucket is too thick for anything. Any pro will tell you that you must thin it down. You want it smooth and spreadable like pudding. Once you have some good mud mixed up and ready to go, put a little bit into your drywall pan. For the 1st coat you will need a 10 inch knife. Always keep your pointer finger in the center of the knife, this will give you more control. Always try to keep the finger side of the knife as dry and clean as possible. Most knives have a logo or something on the handle on one side. I always make the logo side my finger side. Decide what side you want your finger side to be and stick to it. If you're flipping the knife all the time it will get all wet, dirty and sloppy and gross. You want your pointer finger to stay dry.
Step 2: Spread one side
Using a drywall pan full of mud and your 10 inch knife, spread a nice even bed of mud on one side of the butt. Start at the ceiling and come down until you meet the recessed joint. If you're doing a lower butt, start an inch off of the floor and come up until you meet the recessed joint.
Just apply nice even pressure on the center of the knife.
Step 3: Feather in outside edge (Right Side)
By moving your finger a little right of center, you will gain more control on the right side of the knife. Slowly pull down the butt, the right corner of the knife is tight against the wall. The left corner of the knife is slightly lifted away from the wall. Practice this a few times. What you want is to leave a little ripple line inside the joint a few inches.
On the right is a close up picture of the ripple. See it? That's what you want.
Step 4: Feather in outside edge (Left side)
Okay, we're going to do the same thing, this time on the left side. Move your finger over to the left. Pull the knife down and leave a nice ripple line inside the joint a few inches..
Now you should have a nice ripple line on each side ?
Step 5: Pull your knife down the middle
Make sure to have your finger in the middle, Bring the knife down nice and easy. Don't push to hard or you will wipe all the mud off. Just nice even pressure. Your butt should now look like the picture below (on the right).
Step 6: Repeat steps 1-5, this time on the left side of the butt.
Spread a nice layer of mud on joint, Ripple the left side (move finger left), Ripple the right side (move finger right).
Pull your knife down the middle
You just 1st coated a butt joint. Let it dry overnight before sanding and applying the 2nd coat.
How about a free video
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