I should have suspected something when the guys at Lowe’s laughed at the question.
I had asked where to find fast-setting drywall compound. They chuckled as they pointed me down the right aisle. One said, “Be sure to choose the 45-minute kind, not the 20-minute kind.” Then they laughed again.
I shouldered the stuff with a big “45” printed on the bag and headed for checkout. At home, I learned a little bit about why they laughed – and a few things that might help you if you’re tempted to grab a bag for projects at your house.
The fast-setting compound – or “hot mud” – isn’t like the friendly, slow-drying general-purpose compound in the plastic tub.
I’ve used the stuff before, decades ago, and even taught minor drywall repair at Central Piedmont Community College.
And I wasn’t going to use it in a large, visible area. In fact, it wasn’t going to be visible at all. I had to repair a 2-by-2-foot area around some relocated water and drain pipes in a single day, so I could set a vanity before the countertop crew arrived.
The powder mixed easily enough. It spread smoothly.
I watched the clock constantly as I worked.
I felt the minutes tick by. It was kind of like working with someone standing at your elbow urging you to “Hurry, hurry!” (I could still hear the guys from Lowe’s laughing.)
I know what you’re thinking but, no, it didn’t get hard before I could finish a coat.
It hardens quickly, although not as quickly as the bag says. I raced, when I could have just cruised along at a comfortable speed. I was glad I had bought the 45-minute variety, but I never came close to needing that much time to apply a coat.
No, the problem was that hot mud can be hard to sand. I’ve since read that the 20-minute stuff is even harder, but the 45-minute variety was hard aplenty. My drywall sanding screen just wouldn’t do the job.
Coarse sandpaper was a little better but began to scuff the surrounding drywall.
I used some of the hot mud to patch a few nail holes on a visible wall, but even the small spots were hard to sand.
My pal Tim Carter of Ask the Builder (www.askthebuilder.com) says in an online video that you can smooth quick-setting compound with a sponge, as you would general purpose compound. But I didn’t have any luck with that approach.
Finally, I used general purpose drywall compound over the hot mud, then sanded that.
Which, it turns out, is what lots of pros do. They use the quick-setting stuff for a first coat, then finish with a slower drying compound that’s easier to sand – which you can read about online if you do a little research before you plunge into hot mud.
My work looks pretty good. Especially the part that’s hidden behind the new vanity.
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