Warning: I was wrong about using a 6-inch knife for everything

I was at the supply house in Tacoma last week and heard a veteran installer tell his apprentice, 'You wouldn't use a sledgehammer to drive a finish nail.' He was explaining why he uses a 12-inch knife for the final coat on big flats. I tried it on a ceiling job yesterday, and it cut my sanding time by a good 30 minutes because there were way fewer ridges to fix. What other specific knife sizes do you guys use for different parts of a job?

3 comments

3 Comments

valwest1mo agoTop Commenter

That "sledgehammer" logic is flawed because a bigger knife just means more mud to clean up later.

leo2381mo ago

Actually the bigger knife gets the job done in one cut though. Look at clearing a forest, a bulldozer makes a mess but it's done in a day. A handsaw is neat but you'll be there for years. Sometimes you just need the power tool even if it leaves a bigger cleanup, because the alternative is never finishing at all.

wade5581d agoMost Upvoted

valwest, how much extra mud are we actually talking about here? In my experience a 12-inch knife on a big ceiling flat leaves way less excess to scrape than you'd think because you're making one clean pass instead of six overlapped ones. Would be curious if you've tried it on a full room or just going off theory.