How do you mix a plaster scratch coat?

Question

I need to replace a large section of plaster in my home. I'd like to keep the wall original.

Answer 1

Do you mean skim coat?
If its an original plaster wall, there will be two kinds of mix on the wall. the scratch coat has cement in it and is rough to hold onto the lath or screen, and provide a base for the skim coat. The skim coat is a finish layer. No cement, and thinner in consistancy. I would not try to do this, unless you have patience. It is an art form, not just something you throw up. Good luck. Use durabond, it works well, but it is not really sandable.

Answer 2

Don't replace it with plaster. The patch will crack around where it meets the old material.

You can use drywall to replace the missing plaster. I have done it in my house and you can't tell the difference.

First determine how thick the plaster is. Usually it is around 3/8" thick, but mine was actually 1/2" thick.

You can purchase either of those thicknesses in drywall.

Use a large screw driver or box cutter and either chisel out or score out the loose plaster from the lath. Leave the lath in place. I actually removed a 4' x 8' section in one room.

Use drywall screws to attach the board to the lath. While it is good to get it attached to a stud, depending on the size of the patch, you may not need to.

You will have cracks between the patch drywall and the old plaster. Get some lightweight spackling to partially fill the cracks. DO NOT FILL THE ENTIRE CRACK. Just reduce the depth some.

Then use paper joint tape and drywall mud to tape and mud it just like you were doing drywall. Texturize it and you are done.

Good Luck