PSA: I see a lot of guys still using a 6-inch knife for the first coat on flat seams.

I learned this from an old timer in Spokane about 15 years ago. He showed me that a 10-inch knife lays down a much flatter, wider bed of mud that feathers out better, saving you a ton of sanding later. I switched over and it cut my sanding time by nearly a third on a big job last month. Anyone else make that switch and notice a difference?

3 comments

3 Comments

vera_roberts18d ago

Joke's on me, I spent my first year drywalling with a 5-inch putty knife thinking I was a pro. That first flat seam looked like a smashed cake. My foreman finally took pity and handed me a 10-inch. Felt like I was trying to paddle a canoe with a plank for the first 20 minutes, but man the results were night and day. Way less mud wasted and I actually use less sanding discs now, plus my shoulders don't ache quite as bad from all that extra sanding.

noraj792mo ago

My uncle in Tacoma taught me the same thing almost twenty years ago. He handed me a 12-inch knife for taping and it felt huge at first. But you're right, that wider spread puts down such a smooth, thin layer. It really does feather out almost by itself. I still use a smaller knife for corners, but for those long flat seams, the big knife is a total game changer.

the_logan2mo ago

My foreman in Boise made me use a 14 inch knife on a big drywall job. It felt awkward for the first hour but the seams were way smoother. I haven't gone back to a small knife for that first coat since.