The drywall fill coat is the second step in the three-step drywall mudding process.
If you have not already read and completed the first step in the mudding process, the Drywall Tape Coat, please do so before proceeding.
The drywall fill coat is intended to do exactly what the name suggests – fill in the low spots and gaps that may still exist at seams. You will also begin to “feather out” the edges, blending the seams out onto the wall for a seamless appearance.
Before you begin, please ensure that all drywall mudding preparation steps (also found on the Drywall Tape Coat page) are followed.
Necessary Tools and Equipment
Step One: Applying the Drywall Fill Coat
The Drywall Fill Coat will begin to widen the mud bed that you initially applied in the Drywall Tape Coat. The purpose of the drywall mudding process is to essentially make the seam “disappear” as if it had never been there at all. This calls for subtlety and a light touch.
The key to this subtlety is a tapered (or “feathered”) seam.
The initial coat of drywall mud was 4-6” wide. This second coat will widen that to 6-18”.
You will want to taper while you apply mud, leaving the mud coat slightly thicker along the seams and thinning it out as you move further away from the seams.
Using a larger knife makes this easier. You will want to apply pressure on the back of the knife (the one away from the seam). This will create a natural tapering affect.
When applying this coat we have found it easier to place the mud on the wall thicker at first. Follow up with your drywall knife and smooth it out, cutting off the access to achieve your desired look.
Allow 24-36 hours for the drywall mud to completely dry.
Step Two: Sanding the Drywall Fill Coat
Your fill coat will need to be lightly sanded with a sanding sponge, just as the Tape Coat was. A dust mask is a necessity for this part of the process.
Dampen your sanding sponge with water and wring out thoroughly. This will leave the sponge very slightly damp. Using a sanding sponge instead of a sanding block will help eliminate excessive dusting. You can feel free to use a dry sanding block if dust does not concern you.
Focus on removing any spurs in the coat, but also on the all-important taper. There should be a very slight taper away from the seam, extending out 6-10” inches on the wall. If the mud appears to be applied too thickly in places, remove some of the extra plaster with your sanding sponge.
When finished, run your hand down the wall to feel for a taper. The seam at this point should be so subtle that you are virtually unable to feel any rise in the taper.
Continue to sand until any noticeable rise in the seam has disappeared.
Clean up any dust by wiping the seams with a slightly damp rag. You are now ready for the Drywall Finish Coat.